tablecmds.c

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/*-------------------------------------------------------------------------
 *
 * tablecmds.c
 *    Commands for creating and altering table structures and settings
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/commands/tablecmds.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/attmap.h"
#include "access/genam.h"
#include "access/gist.h"
#include "access/heapam.h"
#include "access/heapam_xlog.h"
#include "access/multixact.h"
#include "access/reloptions.h"
#include "access/relscan.h"
#include "access/sysattr.h"
#include "access/tableam.h"
#include "access/toast_compression.h"
#include "access/xact.h"
#include "access/xlog.h"
#include "access/xloginsert.h"
#include "catalog/catalog.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/namespace.h"
#include "catalog/objectaccess.h"
#include "catalog/partition.h"
#include "catalog/pg_am.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_depend.h"
#include "catalog/pg_foreign_table.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_largeobject.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_policy.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_publication_rel.h"
#include "catalog/pg_rewrite.h"
#include "catalog/pg_statistic_ext.h"
#include "catalog/pg_tablespace.h"
#include "catalog/pg_trigger.h"
#include "catalog/pg_type.h"
#include "catalog/storage.h"
#include "catalog/storage_xlog.h"
#include "catalog/toasting.h"
#include "commands/cluster.h"
#include "commands/comment.h"
#include "commands/defrem.h"
#include "commands/event_trigger.h"
#include "commands/sequence.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "commands/trigger.h"
#include "commands/typecmds.h"
#include "commands/user.h"
#include "commands/vacuum.h"
#include "common/int.h"
#include "executor/executor.h"
#include "foreign/fdwapi.h"
#include "foreign/foreign.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "nodes/parsenodes.h"
#include "optimizer/optimizer.h"
#include "parser/parse_coerce.h"
#include "parser/parse_collate.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "parser/parse_type.h"
#include "parser/parse_utilcmd.h"
#include "parser/parser.h"
#include "partitioning/partbounds.h"
#include "partitioning/partdesc.h"
#include "pgstat.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/lock.h"
#include "storage/predicate.h"
#include "storage/smgr.h"
#include "tcop/utility.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/partcache.h"
#include "utils/relcache.h"
#include "utils/ruleutils.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/timestamp.h"
#include "utils/typcache.h"
#include "utils/usercontext.h"
 
/*
 * ON COMMIT action list
 */
typedef struct OnCommitItem
{
    Oid         relid;          /* relid of relation */
    OnCommitAction oncommit;    /* what to do at end of xact */
 
    /*
     * If this entry was created during the current transaction,
     * creating_subid is the ID of the creating subxact; if created in a prior
     * transaction, creating_subid is zero.  If deleted during the current
     * transaction, deleting_subid is the ID of the deleting subxact; if no
     * deletion request is pending, deleting_subid is zero.
     */
    SubTransactionId creating_subid;
    SubTransactionId deleting_subid;
} OnCommitItem;
 
static List *on_commits = NIL;
 
 
/*
 * State information for ALTER TABLE
 *
 * The pending-work queue for an ALTER TABLE is a List of AlteredTableInfo
 * structs, one for each table modified by the operation (the named table
 * plus any child tables that are affected).  We save lists of subcommands
 * to apply to this table (possibly modified by parse transformation steps);
 * these lists will be executed in Phase 2.  If a Phase 3 step is needed,
 * necessary information is stored in the constraints and newvals lists.
 *
 * Phase 2 is divided into multiple passes; subcommands are executed in
 * a pass determined by subcommand type.
 */
 
typedef enum AlterTablePass
{
    AT_PASS_UNSET = -1,         /* UNSET will cause ERROR */
    AT_PASS_DROP,               /* DROP (all flavors) */
    AT_PASS_ALTER_TYPE,         /* ALTER COLUMN TYPE */
    AT_PASS_ADD_COL,            /* ADD COLUMN */
    AT_PASS_SET_EXPRESSION,     /* ALTER SET EXPRESSION */
    AT_PASS_OLD_INDEX,          /* re-add existing indexes */
    AT_PASS_OLD_CONSTR,         /* re-add existing constraints */
    /* We could support a RENAME COLUMN pass here, but not currently used */
    AT_PASS_ADD_CONSTR,         /* ADD constraints (initial examination) */
    AT_PASS_COL_ATTRS,          /* set column attributes, eg NOT NULL */
    AT_PASS_ADD_INDEXCONSTR,    /* ADD index-based constraints */
    AT_PASS_ADD_INDEX,          /* ADD indexes */
    AT_PASS_ADD_OTHERCONSTR,    /* ADD other constraints, defaults */
    AT_PASS_MISC,               /* other stuff */
} AlterTablePass;
 
#define AT_NUM_PASSES           (AT_PASS_MISC + 1)
 
typedef struct AlteredTableInfo
{
    /* Information saved before any work commences: */
    Oid         relid;          /* Relation to work on */
    char        relkind;        /* Its relkind */
    TupleDesc   oldDesc;        /* Pre-modification tuple descriptor */
 
    /*
     * Transiently set during Phase 2, normally set to NULL.
     *
     * ATRewriteCatalogs sets this when it starts, and closes when ATExecCmd
     * returns control.  This can be exploited by ATExecCmd subroutines to
     * close/reopen across transaction boundaries.
     */
    Relation    rel;
 
    /* Information saved by Phase 1 for Phase 2: */
    List       *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
    /* Information saved by Phases 1/2 for Phase 3: */
    List       *constraints;    /* List of NewConstraint */
    List       *newvals;        /* List of NewColumnValue */
    List       *afterStmts;     /* List of utility command parsetrees */
    bool        verify_new_notnull; /* T if we should recheck NOT NULL */
    int         rewrite;        /* Reason for forced rewrite, if any */
    bool        chgAccessMethod;    /* T if SET ACCESS METHOD is used */
    Oid         newAccessMethod;    /* new access method; 0 means no change,
                                     * if above is true */
    Oid         newTableSpace;  /* new tablespace; 0 means no change */
    bool        chgPersistence; /* T if SET LOGGED/UNLOGGED is used */
    char        newrelpersistence;  /* if above is true */
    Expr       *partition_constraint;   /* for attach partition validation */
    /* true, if validating default due to some other attach/detach */
    bool        validate_default;
    /* Objects to rebuild after completing ALTER TYPE operations */
    List       *changedConstraintOids;  /* OIDs of constraints to rebuild */
    List       *changedConstraintDefs;  /* string definitions of same */
    List       *changedIndexOids;   /* OIDs of indexes to rebuild */
    List       *changedIndexDefs;   /* string definitions of same */
    char       *replicaIdentityIndex;   /* index to reset as REPLICA IDENTITY */
    char       *clusterOnIndex; /* index to use for CLUSTER */
    List       *changedStatisticsOids;  /* OIDs of statistics to rebuild */
    List       *changedStatisticsDefs;  /* string definitions of same */
} AlteredTableInfo;
 
/* Struct describing one new constraint to check in Phase 3 scan */
/* Note: new not-null constraints are handled elsewhere */
typedef struct NewConstraint
{
    char       *name;           /* Constraint name, or NULL if none */
    ConstrType  contype;        /* CHECK or FOREIGN */
    Oid         refrelid;       /* PK rel, if FOREIGN */
    Oid         refindid;       /* OID of PK's index, if FOREIGN */
    bool        conwithperiod;  /* Whether the new FOREIGN KEY uses PERIOD */
    Oid         conid;          /* OID of pg_constraint entry, if FOREIGN */
    Node       *qual;           /* Check expr or CONSTR_FOREIGN Constraint */
    ExprState  *qualstate;      /* Execution state for CHECK expr */
} NewConstraint;
 
/*
 * Struct describing one new column value that needs to be computed during
 * Phase 3 copy (this could be either a new column with a non-null default, or
 * a column that we're changing the type of).  Columns without such an entry
 * are just copied from the old table during ATRewriteTable.  Note that the
 * expr is an expression over *old* table values, except when is_generated
 * is true; then it is an expression over columns of the *new* tuple.
 */
typedef struct NewColumnValue
{
    AttrNumber  attnum;         /* which column */
    Expr       *expr;           /* expression to compute */
    ExprState  *exprstate;      /* execution state */
    bool        is_generated;   /* is it a GENERATED expression? */
} NewColumnValue;
 
/*
 * Error-reporting support for RemoveRelations
 */
struct dropmsgstrings
{
    char        kind;
    int         nonexistent_code;
    const char *nonexistent_msg;
    const char *skipping_msg;
    const char *nota_msg;
    const char *drophint_msg;
};
 
static const struct dropmsgstrings dropmsgstringarray[] = {
    {RELKIND_RELATION,
        ERRCODE_UNDEFINED_TABLE,
        gettext_noop("table \"%s\" does not exist"),
        gettext_noop("table \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not a table"),
    gettext_noop("Use DROP TABLE to remove a table.")},
    {RELKIND_SEQUENCE,
        ERRCODE_UNDEFINED_TABLE,
        gettext_noop("sequence \"%s\" does not exist"),
        gettext_noop("sequence \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not a sequence"),
    gettext_noop("Use DROP SEQUENCE to remove a sequence.")},
    {RELKIND_VIEW,
        ERRCODE_UNDEFINED_TABLE,
        gettext_noop("view \"%s\" does not exist"),
        gettext_noop("view \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not a view"),
    gettext_noop("Use DROP VIEW to remove a view.")},
    {RELKIND_MATVIEW,
        ERRCODE_UNDEFINED_TABLE,
        gettext_noop("materialized view \"%s\" does not exist"),
        gettext_noop("materialized view \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not a materialized view"),
    gettext_noop("Use DROP MATERIALIZED VIEW to remove a materialized view.")},
    {RELKIND_INDEX,
        ERRCODE_UNDEFINED_OBJECT,
        gettext_noop("index \"%s\" does not exist"),
        gettext_noop("index \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not an index"),
    gettext_noop("Use DROP INDEX to remove an index.")},
    {RELKIND_COMPOSITE_TYPE,
        ERRCODE_UNDEFINED_OBJECT,
        gettext_noop("type \"%s\" does not exist"),
        gettext_noop("type \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not a type"),
    gettext_noop("Use DROP TYPE to remove a type.")},
    {RELKIND_FOREIGN_TABLE,
        ERRCODE_UNDEFINED_OBJECT,
        gettext_noop("foreign table \"%s\" does not exist"),
        gettext_noop("foreign table \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not a foreign table"),
    gettext_noop("Use DROP FOREIGN TABLE to remove a foreign table.")},
    {RELKIND_PARTITIONED_TABLE,
        ERRCODE_UNDEFINED_TABLE,
        gettext_noop("table \"%s\" does not exist"),
        gettext_noop("table \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not a table"),
    gettext_noop("Use DROP TABLE to remove a table.")},
    {RELKIND_PARTITIONED_INDEX,
        ERRCODE_UNDEFINED_OBJECT,
        gettext_noop("index \"%s\" does not exist"),
        gettext_noop("index \"%s\" does not exist, skipping"),
        gettext_noop("\"%s\" is not an index"),
    gettext_noop("Use DROP INDEX to remove an index.")},
    {'\0', 0, NULL, NULL, NULL, NULL}
};
 
/* communication between RemoveRelations and RangeVarCallbackForDropRelation */
struct DropRelationCallbackState
{
    /* These fields are set by RemoveRelations: */
    char        expected_relkind;
    LOCKMODE    heap_lockmode;
    /* These fields are state to track which subsidiary locks are held: */
    Oid         heapOid;
    Oid         partParentOid;
    /* These fields are passed back by RangeVarCallbackForDropRelation: */
    char        actual_relkind;
    char        actual_relpersistence;
};
 
/* Alter table target-type flags for ATSimplePermissions */
#define     ATT_TABLE               0x0001
#define     ATT_VIEW                0x0002
#define     ATT_MATVIEW             0x0004
#define     ATT_INDEX               0x0008
#define     ATT_COMPOSITE_TYPE      0x0010
#define     ATT_FOREIGN_TABLE       0x0020
#define     ATT_PARTITIONED_INDEX   0x0040
#define     ATT_SEQUENCE            0x0080
#define     ATT_PARTITIONED_TABLE   0x0100
 
/*
 * ForeignTruncateInfo
 *
 * Information related to truncation of foreign tables.  This is used for
 * the elements in a hash table. It uses the server OID as lookup key,
 * and includes a per-server list of all foreign tables involved in the
 * truncation.
 */
typedef struct ForeignTruncateInfo
{
    Oid         serverid;
    List       *rels;
} ForeignTruncateInfo;
 
/* Partial or complete FK creation in addFkConstraint() */
typedef enum addFkConstraintSides
{
    addFkReferencedSide,
    addFkReferencingSide,
    addFkBothSides,
} addFkConstraintSides;
 
/*
 * Partition tables are expected to be dropped when the parent partitioned
 * table gets dropped. Hence for partitioning we use AUTO dependency.
 * Otherwise, for regular inheritance use NORMAL dependency.
 */
#define child_dependency_type(child_is_partition)   \
    ((child_is_partition) ? DEPENDENCY_AUTO : DEPENDENCY_NORMAL)
 
static void truncate_check_rel(Oid relid, Form_pg_class reltuple);
static void truncate_check_perms(Oid relid, Form_pg_class reltuple);
static void truncate_check_activity(Relation rel);
static void RangeVarCallbackForTruncate(const RangeVar *relation,
                                        Oid relId, Oid oldRelId, void *arg);
static List *MergeAttributes(List *columns, const List *supers, char relpersistence,
                             bool is_partition, List **supconstr);
static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
static void MergeChildAttribute(List *inh_columns, int exist_attno, int newcol_attno, const ColumnDef *newdef);
static ColumnDef *MergeInheritedAttribute(List *inh_columns, int exist_attno, const ColumnDef *newdef);
static void MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel, bool ispartition);
static void MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel);
static void StoreCatalogInheritance(Oid relationId, List *supers,
                                    bool child_is_partition);
static void StoreCatalogInheritance1(Oid relationId, Oid parentOid,
                                     int32 seqNumber, Relation inhRelation,
                                     bool child_is_partition);
static int  findAttrByName(const char *attributeName, const List *columns);
static void AlterIndexNamespaces(Relation classRel, Relation rel,
                                 Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved);
static void AlterSeqNamespaces(Relation classRel, Relation rel,
                               Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved,
                               LOCKMODE lockmode);
static ObjectAddress ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
                                           bool recurse, bool recursing, LOCKMODE lockmode);
static bool ATExecAlterConstrRecurse(Constraint *cmdcon, Relation conrel, Relation tgrel,
                                     Relation rel, HeapTuple contuple, List **otherrelids,
                                     LOCKMODE lockmode);
static ObjectAddress ATExecValidateConstraint(List **wqueue,
                                              Relation rel, char *constrName,
                                              bool recurse, bool recursing, LOCKMODE lockmode);
static int  transformColumnNameList(Oid relId, List *colList,
                                    int16 *attnums, Oid *atttypids);
static int  transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
                                       List **attnamelist,
                                       int16 *attnums, Oid *atttypids,
                                       Oid *opclasses, bool *pk_has_without_overlaps);
static Oid  transformFkeyCheckAttrs(Relation pkrel,
                                    int numattrs, int16 *attnums,
                                    bool with_period, Oid *opclasses,
                                    bool *pk_has_without_overlaps);
static void checkFkeyPermissions(Relation rel, int16 *attnums, int natts);
static CoercionPathType findFkeyCast(Oid targetTypeId, Oid sourceTypeId,
                                     Oid *funcid);
static void validateForeignKeyConstraint(char *conname,
                                         Relation rel, Relation pkrel,
                                         Oid pkindOid, Oid constraintOid, bool hasperiod);
static void CheckAlterTableIsSafe(Relation rel);
static void ATController(AlterTableStmt *parsetree,
                         Relation rel, List *cmds, bool recurse, LOCKMODE lockmode,
                         AlterTableUtilityContext *context);
static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
                      bool recurse, bool recursing, LOCKMODE lockmode,
                      AlterTableUtilityContext *context);
static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
                              AlterTableUtilityContext *context);
static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
                      AlterTableCmd *cmd, LOCKMODE lockmode, AlterTablePass cur_pass,
                      AlterTableUtilityContext *context);
static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
                                          Relation rel, AlterTableCmd *cmd,
                                          bool recurse, LOCKMODE lockmode,
                                          AlterTablePass cur_pass,
                                          AlterTableUtilityContext *context);
static void ATRewriteTables(AlterTableStmt *parsetree,
                            List **wqueue, LOCKMODE lockmode,
                            AlterTableUtilityContext *context);
static void ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode);
static AlteredTableInfo *ATGetQueueEntry(List **wqueue, Relation rel);
static void ATSimplePermissions(AlterTableType cmdtype, Relation rel, int allowed_targets);
static void ATSimpleRecursion(List **wqueue, Relation rel,
                              AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode,
                              AlterTableUtilityContext *context);
static void ATCheckPartitionsNotInUse(Relation rel, LOCKMODE lockmode);
static void ATTypedTableRecursion(List **wqueue, Relation rel, AlterTableCmd *cmd,
                                  LOCKMODE lockmode,
                                  AlterTableUtilityContext *context);
static List *find_typed_table_dependencies(Oid typeOid, const char *typeName,
                                           DropBehavior behavior);
static void ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
                            bool is_view, AlterTableCmd *cmd, LOCKMODE lockmode,
                            AlterTableUtilityContext *context);
static ObjectAddress ATExecAddColumn(List **wqueue, AlteredTableInfo *tab,
                                     Relation rel, AlterTableCmd **cmd,
                                     bool recurse, bool recursing,
                                     LOCKMODE lockmode, AlterTablePass cur_pass,
                                     AlterTableUtilityContext *context);
static bool check_for_column_name_collision(Relation rel, const char *colname,
                                            bool if_not_exists);
static void add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid);
static void add_column_collation_dependency(Oid relid, int32 attnum, Oid collid);
static ObjectAddress ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode);
static void ATPrepSetNotNull(List **wqueue, Relation rel,
                             AlterTableCmd *cmd, bool recurse, bool recursing,
                             LOCKMODE lockmode,
                             AlterTableUtilityContext *context);
static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
                                      const char *colName, LOCKMODE lockmode);
static void ATExecCheckNotNull(AlteredTableInfo *tab, Relation rel,
                               const char *colName, LOCKMODE lockmode);
static bool NotNullImpliedByRelConstraints(Relation rel, Form_pg_attribute attr);
static bool ConstraintImpliedByRelConstraint(Relation scanrel,
                                             List *testConstraint, List *provenConstraint);
static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
                                         Node *newDefault, LOCKMODE lockmode);
static ObjectAddress ATExecCookedColumnDefault(Relation rel, AttrNumber attnum,
                                               Node *newDefault);
static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
                                       Node *def, LOCKMODE lockmode, bool recurse, bool recursing);
static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
                                       Node *def, LOCKMODE lockmode, bool recurse, bool recursing);
static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode,
                                        bool recurse, bool recursing);
static ObjectAddress ATExecSetExpression(AlteredTableInfo *tab, Relation rel, const char *colName,
                                         Node *newExpr, LOCKMODE lockmode);
static void ATPrepDropExpression(Relation rel, AlterTableCmd *cmd, bool recurse, bool recursing, LOCKMODE lockmode);
static ObjectAddress ATExecDropExpression(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode);
static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName, int16 colNum,
                                         Node *newValue, LOCKMODE lockmode);
static ObjectAddress ATExecSetOptions(Relation rel, const char *colName,
                                      Node *options, bool isReset, LOCKMODE lockmode);
static ObjectAddress ATExecSetStorage(Relation rel, const char *colName,
                                      Node *newValue, LOCKMODE lockmode);
static void ATPrepDropColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
                             AlterTableCmd *cmd, LOCKMODE lockmode,
                             AlterTableUtilityContext *context);
static ObjectAddress ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
                                      DropBehavior behavior,
                                      bool recurse, bool recursing,
                                      bool missing_ok, LOCKMODE lockmode,
                                      ObjectAddresses *addrs);
static ObjectAddress ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
                                    IndexStmt *stmt, bool is_rebuild, LOCKMODE lockmode);
static ObjectAddress ATExecAddStatistics(AlteredTableInfo *tab, Relation rel,
                                         CreateStatsStmt *stmt, bool is_rebuild, LOCKMODE lockmode);
static ObjectAddress ATExecAddConstraint(List **wqueue,
                                         AlteredTableInfo *tab, Relation rel,
                                         Constraint *newConstraint, bool recurse, bool is_readd,
                                         LOCKMODE lockmode);
static char *ChooseForeignKeyConstraintNameAddition(List *colnames);
static ObjectAddress ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
                                              IndexStmt *stmt, LOCKMODE lockmode);
static ObjectAddress ATAddCheckConstraint(List **wqueue,
                                          AlteredTableInfo *tab, Relation rel,
                                          Constraint *constr,
                                          bool recurse, bool recursing, bool is_readd,
                                          LOCKMODE lockmode);
static ObjectAddress ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab,
                                               Relation rel, Constraint *fkconstraint,
                                               bool recurse, bool recursing,
                                               LOCKMODE lockmode);
static void validateFkOnDeleteSetColumns(int numfks, const int16 *fkattnums,
                                         int numfksetcols, const int16 *fksetcolsattnums,
                                         List *fksetcols);
static ObjectAddress addFkConstraint(addFkConstraintSides fkside,
                                     char *constraintname,
                                     Constraint *fkconstraint, Relation rel,
                                     Relation pkrel, Oid indexOid,
                                     Oid parentConstr,
                                     int numfks, int16 *pkattnum, int16 *fkattnum,
                                     Oid *pfeqoperators, Oid *ppeqoperators,
                                     Oid *ffeqoperators, int numfkdelsetcols,
                                     int16 *fkdelsetcols, bool is_internal,
                                     bool with_period);
static void addFkRecurseReferenced(Constraint *fkconstraint,
                                   Relation rel, Relation pkrel, Oid indexOid, Oid parentConstr,
                                   int numfks, int16 *pkattnum, int16 *fkattnum,
                                   Oid *pfeqoperators, Oid *ppeqoperators, Oid *ffeqoperators,
                                   int numfkdelsetcols, int16 *fkdelsetcols,
                                   bool old_check_ok,
                                   Oid parentDelTrigger, Oid parentUpdTrigger,
                                   bool with_period);
static void addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint,
                                    Relation rel, Relation pkrel, Oid indexOid, Oid parentConstr,
                                    int numfks, int16 *pkattnum, int16 *fkattnum,
                                    Oid *pfeqoperators, Oid *ppeqoperators, Oid *ffeqoperators,
                                    int numfkdelsetcols, int16 *fkdelsetcols,
                                    bool old_check_ok, LOCKMODE lockmode,
                                    Oid parentInsTrigger, Oid parentUpdTrigger,
                                    bool with_period);
static void CloneForeignKeyConstraints(List **wqueue, Relation parentRel,
                                       Relation partitionRel);
static void CloneFkReferenced(Relation parentRel, Relation partitionRel);
static void CloneFkReferencing(List **wqueue, Relation parentRel,
                               Relation partRel);
static void createForeignKeyCheckTriggers(Oid myRelOid, Oid refRelOid,
                                          Constraint *fkconstraint, Oid constraintOid,
                                          Oid indexOid,
                                          Oid parentInsTrigger, Oid parentUpdTrigger,
                                          Oid *insertTrigOid, Oid *updateTrigOid);
static void createForeignKeyActionTriggers(Relation rel, Oid refRelOid,
                                           Constraint *fkconstraint, Oid constraintOid,
                                           Oid indexOid,
                                           Oid parentDelTrigger, Oid parentUpdTrigger,
                                           Oid *deleteTrigOid, Oid *updateTrigOid);
static bool tryAttachPartitionForeignKey(ForeignKeyCacheInfo *fk,
                                         Oid partRelid,
                                         Oid parentConstrOid, int numfks,
                                         AttrNumber *mapped_conkey, AttrNumber *confkey,
                                         Oid *conpfeqop,
                                         Oid parentInsTrigger,
                                         Oid parentUpdTrigger,
                                         Relation trigrel);
static void GetForeignKeyActionTriggers(Relation trigrel,
                                        Oid conoid, Oid confrelid, Oid conrelid,
                                        Oid *deleteTriggerOid,
                                        Oid *updateTriggerOid);
static void GetForeignKeyCheckTriggers(Relation trigrel,
                                       Oid conoid, Oid confrelid, Oid conrelid,
                                       Oid *insertTriggerOid,
                                       Oid *updateTriggerOid);
static void ATExecDropConstraint(Relation rel, const char *constrName,
                                 DropBehavior behavior,
                                 bool recurse, bool recursing,
                                 bool missing_ok, LOCKMODE lockmode);
static void ATPrepAlterColumnType(List **wqueue,
                                  AlteredTableInfo *tab, Relation rel,
                                  bool recurse, bool recursing,
                                  AlterTableCmd *cmd, LOCKMODE lockmode,
                                  AlterTableUtilityContext *context);
static bool ATColumnChangeRequiresRewrite(Node *expr, AttrNumber varattno);
static ObjectAddress ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
                                           AlterTableCmd *cmd, LOCKMODE lockmode);
static void RememberAllDependentForRebuilding(AlteredTableInfo *tab, AlterTableType subtype,
                                              Relation rel, AttrNumber attnum, const char *colName);
static void RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab);
static void RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab);
static void RememberStatisticsForRebuilding(Oid stxoid, AlteredTableInfo *tab);
static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab,
                                   LOCKMODE lockmode);
static void ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId,
                                 char *cmd, List **wqueue, LOCKMODE lockmode,
                                 bool rewrite);
static void RebuildConstraintComment(AlteredTableInfo *tab, AlterTablePass pass,
                                     Oid objid, Relation rel, List *domname,
                                     const char *conname);
static void TryReuseIndex(Oid oldId, IndexStmt *stmt);
static void TryReuseForeignKey(Oid oldId, Constraint *con);
static ObjectAddress ATExecAlterColumnGenericOptions(Relation rel, const char *colName,
                                                     List *options, LOCKMODE lockmode);
static void change_owner_fix_column_acls(Oid relationOid,
                                         Oid oldOwnerId, Oid newOwnerId);
static void change_owner_recurse_to_sequences(Oid relationOid,
                                              Oid newOwnerId, LOCKMODE lockmode);
static ObjectAddress ATExecClusterOn(Relation rel, const char *indexName,
                                     LOCKMODE lockmode);
static void ATExecDropCluster(Relation rel, LOCKMODE lockmode);
static void ATPrepSetAccessMethod(AlteredTableInfo *tab, Relation rel, const char *amname);
static void ATExecSetAccessMethodNoStorage(Relation rel, Oid newAccessMethodId);
static void ATPrepChangePersistence(AlteredTableInfo *tab, Relation rel,
                                    bool toLogged);
static void ATPrepSetTableSpace(AlteredTableInfo *tab, Relation rel,
                                const char *tablespacename, LOCKMODE lockmode);
static void ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode);
static void ATExecSetTableSpaceNoStorage(Relation rel, Oid newTableSpace);
static void ATExecSetRelOptions(Relation rel, List *defList,
                                AlterTableType operation,
                                LOCKMODE lockmode);
static void ATExecEnableDisableTrigger(Relation rel, const char *trigname,
                                       char fires_when, bool skip_system, bool recurse,
                                       LOCKMODE lockmode);
static void ATExecEnableDisableRule(Relation rel, const char *rulename,
                                    char fires_when, LOCKMODE lockmode);
static void ATPrepAddInherit(Relation child_rel);
static ObjectAddress ATExecAddInherit(Relation child_rel, RangeVar *parent, LOCKMODE lockmode);
static ObjectAddress ATExecDropInherit(Relation rel, RangeVar *parent, LOCKMODE lockmode);
static void drop_parent_dependency(Oid relid, Oid refclassid, Oid refobjid,
                                   DependencyType deptype);
static ObjectAddress ATExecAddOf(Relation rel, const TypeName *ofTypename, LOCKMODE lockmode);
static void ATExecDropOf(Relation rel, LOCKMODE lockmode);
static void ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKMODE lockmode);
static void ATExecGenericOptions(Relation rel, List *options);
static void ATExecSetRowSecurity(Relation rel, bool rls);
static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
static ObjectAddress ATExecSetCompression(Relation rel,
                                          const char *column, Node *newValue, LOCKMODE lockmode);
 
static void index_copy_data(Relation rel, RelFileLocator newrlocator);
static const char *storage_name(char c);
 
static void RangeVarCallbackForDropRelation(const RangeVar *rel, Oid relOid,
                                            Oid oldRelOid, void *arg);
static void RangeVarCallbackForAlterRelation(const RangeVar *rv, Oid relid,
                                             Oid oldrelid, void *arg);
static PartitionSpec *transformPartitionSpec(Relation rel, PartitionSpec *partspec);
static void ComputePartitionAttrs(ParseState *pstate, Relation rel, List *partParams, AttrNumber *partattrs,
                                  List **partexprs, Oid *partopclass, Oid *partcollation,
                                  PartitionStrategy strategy);
static void CreateInheritance(Relation child_rel, Relation parent_rel, bool ispartition);
static void RemoveInheritance(Relation child_rel, Relation parent_rel,
                              bool expect_detached);
static ObjectAddress ATExecAttachPartition(List **wqueue, Relation rel,
                                           PartitionCmd *cmd,
                                           AlterTableUtilityContext *context);
static void AttachPartitionEnsureIndexes(List **wqueue, Relation rel, Relation attachrel);
static void QueuePartitionConstraintValidation(List **wqueue, Relation scanrel,
                                               List *partConstraint,
                                               bool validate_default);
static void CloneRowTriggersToPartition(Relation parent, Relation partition);
static void DetachAddConstraintIfNeeded(List **wqueue, Relation partRel);
static void DropClonedTriggersFromPartition(Oid partitionId);
static ObjectAddress ATExecDetachPartition(List **wqueue, AlteredTableInfo *tab,
                                           Relation rel, RangeVar *name,
                                           bool concurrent);
static void DetachPartitionFinalize(Relation rel, Relation partRel,
                                    bool concurrent, Oid defaultPartOid);
static ObjectAddress ATExecDetachPartitionFinalize(Relation rel, RangeVar *name);
static ObjectAddress ATExecAttachPartitionIdx(List **wqueue, Relation parentIdx,
                                              RangeVar *name);
static void validatePartitionedIndex(Relation partedIdx, Relation partedTbl);
static void refuseDupeIndexAttach(Relation parentIdx, Relation partIdx,
                                  Relation partitionTbl);
static List *GetParentedForeignKeyRefs(Relation partition);
static void ATDetachCheckNoForeignKeyRefs(Relation partition);
static char GetAttributeCompression(Oid atttypid, const char *compression);
static char GetAttributeStorage(Oid atttypid, const char *storagemode);
 
 
/* ----------------------------------------------------------------
 *      DefineRelation
 *              Creates a new relation.
 *
 * stmt carries parsetree information from an ordinary CREATE TABLE statement.
 * The other arguments are used to extend the behavior for other cases:
 * relkind: relkind to assign to the new relation
 * ownerId: if not InvalidOid, use this as the new relation's owner.
 * typaddress: if not null, it's set to the pg_type entry's address.
 * queryString: for error reporting
 *
 * Note that permissions checks are done against current user regardless of
 * ownerId.  A nonzero ownerId is used when someone is creating a relation
 * "on behalf of" someone else, so we still want to see that the current user
 * has permissions to do it.
 *
 * If successful, returns the address of the new relation.
 * ----------------------------------------------------------------
 */
ObjectAddress
DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
               ObjectAddress *typaddress, const char *queryString)
{
    char        relname[NAMEDATALEN];
    Oid         namespaceId;
    Oid         relationId;
    Oid         tablespaceId;
    Relation    rel;
    TupleDesc   descriptor;
    List       *inheritOids;
    List       *old_constraints;
    List       *rawDefaults;
    List       *cookedDefaults;
    Datum       reloptions;
    ListCell   *listptr;
    AttrNumber  attnum;
    bool        partitioned;
    const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
    Oid         ofTypeId;
    ObjectAddress address;
    LOCKMODE    parentLockmode;
    Oid         accessMethodId = InvalidOid;
 
    /*
     * Truncate relname to appropriate length (probably a waste of time, as
     * parser should have done this already).
     */
    strlcpy(relname, stmt->relation->relname, NAMEDATALEN);
 
    /*
     * Check consistency of arguments
     */
    if (stmt->oncommit != ONCOMMIT_NOOP
        && stmt->relation->relpersistence != RELPERSISTENCE_TEMP)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("ON COMMIT can only be used on temporary tables")));
 
    if (stmt->partspec != NULL)
    {
        if (relkind != RELKIND_RELATION)
            elog(ERROR, "unexpected relkind: %d", (int) relkind);
 
        relkind = RELKIND_PARTITIONED_TABLE;
        partitioned = true;
    }
    else
        partitioned = false;
 
    if (relkind == RELKIND_PARTITIONED_TABLE &&
        stmt->relation->relpersistence == RELPERSISTENCE_UNLOGGED)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("partitioned tables cannot be unlogged")));
 
    /*
     * Look up the namespace in which we are supposed to create the relation,
     * check we have permission to create there, lock it against concurrent
     * drop, and mark stmt->relation as RELPERSISTENCE_TEMP if a temporary
     * namespace is selected.
     */
    namespaceId =
        RangeVarGetAndCheckCreationNamespace(stmt->relation, NoLock, NULL);
 
    /*
     * Security check: disallow creating temp tables from security-restricted
     * code.  This is needed because calling code might not expect untrusted
     * tables to appear in pg_temp at the front of its search path.
     */
    if (stmt->relation->relpersistence == RELPERSISTENCE_TEMP
        && InSecurityRestrictedOperation())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("cannot create temporary table within security-restricted operation")));
 
    /*
     * Determine the lockmode to use when scanning parents.  A self-exclusive
     * lock is needed here.
     *
     * For regular inheritance, if two backends attempt to add children to the
     * same parent simultaneously, and that parent has no pre-existing
     * children, then both will attempt to update the parent's relhassubclass
     * field, leading to a "tuple concurrently updated" error.  Also, this
     * interlocks against a concurrent ANALYZE on the parent table, which
     * might otherwise be attempting to clear the parent's relhassubclass
     * field, if its previous children were recently dropped.
     *
     * If the child table is a partition, then we instead grab an exclusive
     * lock on the parent because its partition descriptor will be changed by
     * addition of the new partition.
     */
    parentLockmode = (stmt->partbound != NULL ? AccessExclusiveLock :
                      ShareUpdateExclusiveLock);
 
    /* Determine the list of OIDs of the parents. */
    inheritOids = NIL;
    foreach(listptr, stmt->inhRelations)
    {
        RangeVar   *rv = (RangeVar *) lfirst(listptr);
        Oid         parentOid;
 
        parentOid = RangeVarGetRelid(rv, parentLockmode, false);
 
        /*
         * Reject duplications in the list of parents.
         */
        if (list_member_oid(inheritOids, parentOid))
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_TABLE),
                     errmsg("relation \"%s\" would be inherited from more than once",
                            get_rel_name(parentOid))));
 
        inheritOids = lappend_oid(inheritOids, parentOid);
    }
 
    /*
     * Select tablespace to use: an explicitly indicated one, or (in the case
     * of a partitioned table) the parent's, if it has one.
     */
    if (stmt->tablespacename)
    {
        tablespaceId = get_tablespace_oid(stmt->tablespacename, false);
 
        if (partitioned && tablespaceId == MyDatabaseTableSpace)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot specify default tablespace for partitioned relations")));
    }
    else if (stmt->partbound)
    {
        Assert(list_length(inheritOids) == 1);
        tablespaceId = get_rel_tablespace(linitial_oid(inheritOids));
    }
    else
        tablespaceId = InvalidOid;
 
    /* still nothing? use the default */
    if (!OidIsValid(tablespaceId))
        tablespaceId = GetDefaultTablespace(stmt->relation->relpersistence,
                                            partitioned);
 
    /* Check permissions except when using database's default */
    if (OidIsValid(tablespaceId) && tablespaceId != MyDatabaseTableSpace)
    {
        AclResult   aclresult;
 
        aclresult = object_aclcheck(TableSpaceRelationId, tablespaceId, GetUserId(),
                                    ACL_CREATE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, OBJECT_TABLESPACE,
                           get_tablespace_name(tablespaceId));
    }
 
    /* In all cases disallow placing user relations in pg_global */
    if (tablespaceId == GLOBALTABLESPACE_OID)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("only shared relations can be placed in pg_global tablespace")));
 
    /* Identify user ID that will own the table */
    if (!OidIsValid(ownerId))
        ownerId = GetUserId();
 
    /*
     * Parse and validate reloptions, if any.
     */
    reloptions = transformRelOptions((Datum) 0, stmt->options, NULL, validnsps,
                                     true, false);
 
    switch (relkind)
    {
        case RELKIND_VIEW:
            (void) view_reloptions(reloptions, true);
            break;
        case RELKIND_PARTITIONED_TABLE:
            (void) partitioned_table_reloptions(reloptions, true);
            break;
        default:
            (void) heap_reloptions(relkind, reloptions, true);
    }
 
    if (stmt->ofTypename)
    {
        AclResult   aclresult;
 
        ofTypeId = typenameTypeId(NULL, stmt->ofTypename);
 
        aclresult = object_aclcheck(TypeRelationId, ofTypeId, GetUserId(), ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error_type(aclresult, ofTypeId);
    }
    else
        ofTypeId = InvalidOid;
 
    /*
     * Look up inheritance ancestors and generate relation schema, including
     * inherited attributes.  (Note that stmt->tableElts is destructively
     * modified by MergeAttributes.)
     */
    stmt->tableElts =
        MergeAttributes(stmt->tableElts, inheritOids,
                        stmt->relation->relpersistence,
                        stmt->partbound != NULL,
                        &old_constraints);
 
    /*
     * Create a tuple descriptor from the relation schema.  Note that this
     * deals with column names, types, and not-null constraints, but not
     * default values or CHECK constraints; we handle those below.
     */
    descriptor = BuildDescForRelation(stmt->tableElts);
 
    /*
     * Find columns with default values and prepare for insertion of the
     * defaults.  Pre-cooked (that is, inherited) defaults go into a list of
     * CookedConstraint structs that we'll pass to heap_create_with_catalog,
     * while raw defaults go into a list of RawColumnDefault structs that will
     * be processed by AddRelationNewConstraints.  (We can't deal with raw
     * expressions until we can do transformExpr.)
     *
     * We can set the atthasdef flags now in the tuple descriptor; this just
     * saves StoreAttrDefault from having to do an immediate update of the
     * pg_attribute rows.
     */
    rawDefaults = NIL;
    cookedDefaults = NIL;
    attnum = 0;
 
    foreach(listptr, stmt->tableElts)
    {
        ColumnDef  *colDef = lfirst(listptr);
        Form_pg_attribute attr;
 
        attnum++;
        attr = TupleDescAttr(descriptor, attnum - 1);
 
        if (colDef->raw_default != NULL)
        {
            RawColumnDefault *rawEnt;
 
            Assert(colDef->cooked_default == NULL);
 
            rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
            rawEnt->attnum = attnum;
            rawEnt->raw_default = colDef->raw_default;
            rawEnt->missingMode = false;
            rawEnt->generated = colDef->generated;
            rawDefaults = lappend(rawDefaults, rawEnt);
            attr->atthasdef = true;
        }
        else if (colDef->cooked_default != NULL)
        {
            CookedConstraint *cooked;
 
            cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
            cooked->contype = CONSTR_DEFAULT;
            cooked->conoid = InvalidOid;    /* until created */
            cooked->name = NULL;
            cooked->attnum = attnum;
            cooked->expr = colDef->cooked_default;
            cooked->skip_validation = false;
            cooked->is_local = true;    /* not used for defaults */
            cooked->inhcount = 0;   /* ditto */
            cooked->is_no_inherit = false;
            cookedDefaults = lappend(cookedDefaults, cooked);
            attr->atthasdef = true;
        }
    }
 
    /*
     * For relations with table AM and partitioned tables, select access
     * method to use: an explicitly indicated one, or (in the case of a
     * partitioned table) the parent's, if it has one.
     */
    if (stmt->accessMethod != NULL)
    {
        Assert(RELKIND_HAS_TABLE_AM(relkind) || relkind == RELKIND_PARTITIONED_TABLE);
        accessMethodId = get_table_am_oid(stmt->accessMethod, false);
    }
    else if (RELKIND_HAS_TABLE_AM(relkind) || relkind == RELKIND_PARTITIONED_TABLE)
    {
        if (stmt->partbound)
        {
            Assert(list_length(inheritOids) == 1);
            accessMethodId = get_rel_relam(linitial_oid(inheritOids));
        }
 
        if (RELKIND_HAS_TABLE_AM(relkind) && !OidIsValid(accessMethodId))
            accessMethodId = get_table_am_oid(default_table_access_method, false);
    }
 
    /*
     * Create the relation.  Inherited defaults and constraints are passed in
     * for immediate handling --- since they don't need parsing, they can be
     * stored immediately.
     */
    relationId = heap_create_with_catalog(relname,
                                          namespaceId,
                                          tablespaceId,
                                          InvalidOid,
                                          InvalidOid,
                                          ofTypeId,
                                          ownerId,
                                          accessMethodId,
                                          descriptor,
                                          list_concat(cookedDefaults,
                                                      old_constraints),
                                          relkind,
                                          stmt->relation->relpersistence,
                                          false,
                                          false,
                                          stmt->oncommit,
                                          reloptions,
                                          true,
                                          allowSystemTableMods,
                                          false,
                                          InvalidOid,
                                          typaddress);
 
    /*
     * We must bump the command counter to make the newly-created relation
     * tuple visible for opening.
     */
    CommandCounterIncrement();
 
    /*
     * Open the new relation and acquire exclusive lock on it.  This isn't
     * really necessary for locking out other backends (since they can't see
     * the new rel anyway until we commit), but it keeps the lock manager from
     * complaining about deadlock risks.
     */
    rel = relation_open(relationId, AccessExclusiveLock);
 
    /*
     * Now add any newly specified column default and generation expressions
     * to the new relation.  These are passed to us in the form of raw
     * parsetrees; we need to transform them to executable expression trees
     * before they can be added. The most convenient way to do that is to
     * apply the parser's transformExpr routine, but transformExpr doesn't
     * work unless we have a pre-existing relation. So, the transformation has
     * to be postponed to this final step of CREATE TABLE.
     *
     * This needs to be before processing the partitioning clauses because
     * those could refer to generated columns.
     */
    if (rawDefaults)
        AddRelationNewConstraints(rel, rawDefaults, NIL,
                                  true, true, false, queryString);
 
    /*
     * Make column generation expressions visible for use by partitioning.
     */
    CommandCounterIncrement();
 
    /* Process and store partition bound, if any. */
    if (stmt->partbound)
    {
        PartitionBoundSpec *bound;
        ParseState *pstate;
        Oid         parentId = linitial_oid(inheritOids),
                    defaultPartOid;
        Relation    parent,
                    defaultRel = NULL;
        ParseNamespaceItem *nsitem;
 
        /* Already have strong enough lock on the parent */
        parent = table_open(parentId, NoLock);
 
        /*
         * We are going to try to validate the partition bound specification
         * against the partition key of parentRel, so it better have one.
         */
        if (parent->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("\"%s\" is not partitioned",
                            RelationGetRelationName(parent))));
 
        /*
         * The partition constraint of the default partition depends on the
         * partition bounds of every other partition. It is possible that
         * another backend might be about to execute a query on the default
         * partition table, and that the query relies on previously cached
         * default partition constraints. We must therefore take a table lock
         * strong enough to prevent all queries on the default partition from
         * proceeding until we commit and send out a shared-cache-inval notice
         * that will make them update their index lists.
         *
         * Order of locking: The relation being added won't be visible to
         * other backends until it is committed, hence here in
         * DefineRelation() the order of locking the default partition and the
         * relation being added does not matter. But at all other places we
         * need to lock the default relation before we lock the relation being
         * added or removed i.e. we should take the lock in same order at all
         * the places such that lock parent, lock default partition and then
         * lock the partition so as to avoid a deadlock.
         */
        defaultPartOid =
            get_default_oid_from_partdesc(RelationGetPartitionDesc(parent,
                                                                   true));
        if (OidIsValid(defaultPartOid))
            defaultRel = table_open(defaultPartOid, AccessExclusiveLock);
 
        /* Transform the bound values */
        pstate = make_parsestate(NULL);
        pstate->p_sourcetext = queryString;
 
        /*
         * Add an nsitem containing this relation, so that transformExpr
         * called on partition bound expressions is able to report errors
         * using a proper context.
         */
        nsitem = addRangeTableEntryForRelation(pstate, rel, AccessShareLock,
                                               NULL, false, false);
        addNSItemToQuery(pstate, nsitem, false, true, true);
 
        bound = transformPartitionBound(pstate, parent, stmt->partbound);
 
        /*
         * Check first that the new partition's bound is valid and does not
         * overlap with any of existing partitions of the parent.
         */
        check_new_partition_bound(relname, parent, bound, pstate);
 
        /*
         * If the default partition exists, its partition constraints will
         * change after the addition of this new partition such that it won't
         * allow any row that qualifies for this new partition. So, check that
         * the existing data in the default partition satisfies the constraint
         * as it will exist after adding this partition.
         */
        if (OidIsValid(defaultPartOid))
        {
            check_default_partition_contents(parent, defaultRel, bound);
            /* Keep the lock until commit. */
            table_close(defaultRel, NoLock);
        }
 
        /* Update the pg_class entry. */
        StorePartitionBound(rel, parent, bound);
 
        table_close(parent, NoLock);
    }
 
    /* Store inheritance information for new rel. */
    StoreCatalogInheritance(relationId, inheritOids, stmt->partbound != NULL);
 
    /*
     * Process the partitioning specification (if any) and store the partition
     * key information into the catalog.
     */
    if (partitioned)
    {
        ParseState *pstate;
        int         partnatts;
        AttrNumber  partattrs[PARTITION_MAX_KEYS];
        Oid         partopclass[PARTITION_MAX_KEYS];
        Oid         partcollation[PARTITION_MAX_KEYS];
        List       *partexprs = NIL;
 
        pstate = make_parsestate(NULL);
        pstate->p_sourcetext = queryString;
 
        partnatts = list_length(stmt->partspec->partParams);
 
        /* Protect fixed-size arrays here and in executor */
        if (partnatts > PARTITION_MAX_KEYS)
            ereport(ERROR,
                    (errcode(ERRCODE_TOO_MANY_COLUMNS),
                     errmsg("cannot partition using more than %d columns",
                            PARTITION_MAX_KEYS)));
 
        /*
         * We need to transform the raw parsetrees corresponding to partition
         * expressions into executable expression trees.  Like column defaults
         * and CHECK constraints, we could not have done the transformation
         * earlier.
         */
        stmt->partspec = transformPartitionSpec(rel, stmt->partspec);
 
        ComputePartitionAttrs(pstate, rel, stmt->partspec->partParams,
                              partattrs, &partexprs, partopclass,
                              partcollation, stmt->partspec->strategy);
 
        StorePartitionKey(rel, stmt->partspec->strategy, partnatts, partattrs,
                          partexprs,
                          partopclass, partcollation);
 
        /* make it all visible */
        CommandCounterIncrement();
    }
 
    /*
     * If we're creating a partition, create now all the indexes, triggers,
     * FKs defined in the parent.
     *
     * We can't do it earlier, because DefineIndex wants to know the partition
     * key which we just stored.
     */
    if (stmt->partbound)
    {
        Oid         parentId = linitial_oid(inheritOids);
        Relation    parent;
        List       *idxlist;
        ListCell   *cell;
 
        /* Already have strong enough lock on the parent */
        parent = table_open(parentId, NoLock);
        idxlist = RelationGetIndexList(parent);
 
        /*
         * For each index in the parent table, create one in the partition
         */
        foreach(cell, idxlist)
        {
            Relation    idxRel = index_open(lfirst_oid(cell), AccessShareLock);
            AttrMap    *attmap;
            IndexStmt  *idxstmt;
            Oid         constraintOid;
 
            if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
            {
                if (idxRel->rd_index->indisunique)
                    ereport(ERROR,
                            (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                             errmsg("cannot create foreign partition of partitioned table \"%s\"",
                                    RelationGetRelationName(parent)),
                             errdetail("Table \"%s\" contains indexes that are unique.",
                                       RelationGetRelationName(parent))));
                else
                {
                    index_close(idxRel, AccessShareLock);
                    continue;
                }
            }
 
            attmap = build_attrmap_by_name(RelationGetDescr(rel),
                                           RelationGetDescr(parent),
                                           false);
            idxstmt =
                generateClonedIndexStmt(NULL, idxRel,
                                        attmap, &constraintOid);
            DefineIndex(RelationGetRelid(rel),
                        idxstmt,
                        InvalidOid,
                        RelationGetRelid(idxRel),
                        constraintOid,
                        -1,
                        false, false, false, false, false);
 
            index_close(idxRel, AccessShareLock);
        }
 
        list_free(idxlist);
 
        /*
         * If there are any row-level triggers, clone them to the new
         * partition.
         */
        if (parent->trigdesc != NULL)
            CloneRowTriggersToPartition(parent, rel);
 
        /*
         * And foreign keys too.  Note that because we're freshly creating the
         * table, there is no need to verify these new constraints.
         */
        CloneForeignKeyConstraints(NULL, parent, rel);
 
        table_close(parent, NoLock);
    }
 
    /*
     * Now add any newly specified CHECK constraints to the new relation. Same
     * as for defaults above, but these need to come after partitioning is set
     * up.
     */
    if (stmt->constraints)
        AddRelationNewConstraints(rel, NIL, stmt->constraints,
                                  true, true, false, queryString);
 
    ObjectAddressSet(address, RelationRelationId, relationId);
 
    /*
     * Clean up.  We keep lock on new relation (although it shouldn't be
     * visible to anyone else anyway, until commit).
     */
    relation_close(rel, NoLock);
 
    return address;
}
 
/*
 * BuildDescForRelation
 *
 * Given a list of ColumnDef nodes, build a TupleDesc.
 *
 * Note: This is only for the limited purpose of table and view creation.  Not
 * everything is filled in.  A real tuple descriptor should be obtained from
 * the relcache.
 */
TupleDesc
BuildDescForRelation(const List *columns)
{
    int         natts;
    AttrNumber  attnum;
    ListCell   *l;
    TupleDesc   desc;
    char       *attname;
    Oid         atttypid;
    int32       atttypmod;
    Oid         attcollation;
    int         attdim;
 
    /*
     * allocate a new tuple descriptor
     */
    natts = list_length(columns);
    desc = CreateTemplateTupleDesc(natts);
 
    attnum = 0;
 
    foreach(l, columns)
    {
        ColumnDef  *entry = lfirst(l);
        AclResult   aclresult;
        Form_pg_attribute att;
 
        /*
         * for each entry in the list, get the name and type information from
         * the list and have TupleDescInitEntry fill in the attribute
         * information we need.
         */
        attnum++;
 
        attname = entry->colname;
        typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
 
        aclresult = object_aclcheck(TypeRelationId, atttypid, GetUserId(), ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error_type(aclresult, atttypid);
 
        attcollation = GetColumnDefCollation(NULL, entry, atttypid);
        attdim = list_length(entry->typeName->arrayBounds);
        if (attdim > PG_INT16_MAX)
            ereport(ERROR,
                    errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                    errmsg("too many array dimensions"));
 
        if (entry->typeName->setof)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("column \"%s\" cannot be declared SETOF",
                            attname)));
 
        TupleDescInitEntry(desc, attnum, attname,
                           atttypid, atttypmod, attdim);
        att = TupleDescAttr(desc, attnum - 1);
 
        /* Override TupleDescInitEntry's settings as requested */
        TupleDescInitEntryCollation(desc, attnum, attcollation);
 
        /* Fill in additional stuff not handled by TupleDescInitEntry */
        att->attnotnull = entry->is_not_null;
        att->attislocal = entry->is_local;
        att->attinhcount = entry->inhcount;
        att->attidentity = entry->identity;
        att->attgenerated = entry->generated;
        att->attcompression = GetAttributeCompression(att->atttypid, entry->compression);
        if (entry->storage)
            att->attstorage = entry->storage;
        else if (entry->storage_name)
            att->attstorage = GetAttributeStorage(att->atttypid, entry->storage_name);
    }
 
    return desc;
}
 
/*
 * Emit the right error or warning message for a "DROP" command issued on a
 * non-existent relation
 */
static void
DropErrorMsgNonExistent(RangeVar *rel, char rightkind, bool missing_ok)
{
    const struct dropmsgstrings *rentry;
 
    if (rel->schemaname != NULL &&
        !OidIsValid(LookupNamespaceNoError(rel->schemaname)))
    {
        if (!missing_ok)
        {
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_SCHEMA),
                     errmsg("schema \"%s\" does not exist", rel->schemaname)));
        }
        else
        {
            ereport(NOTICE,
                    (errmsg("schema \"%s\" does not exist, skipping",
                            rel->schemaname)));
        }
        return;
    }
 
    for (rentry = dropmsgstringarray; rentry->kind != '\0'; rentry++)
    {
        if (rentry->kind == rightkind)
        {
            if (!missing_ok)
            {
                ereport(ERROR,
                        (errcode(rentry->nonexistent_code),
                         errmsg(rentry->nonexistent_msg, rel->relname)));
            }
            else
            {
                ereport(NOTICE, (errmsg(rentry->skipping_msg, rel->relname)));
                break;
            }
        }
    }
 
    Assert(rentry->kind != '\0');   /* Should be impossible */
}
 
/*
 * Emit the right error message for a "DROP" command issued on a
 * relation of the wrong type
 */
static void
DropErrorMsgWrongType(const char *relname, char wrongkind, char rightkind)
{
    const struct dropmsgstrings *rentry;
    const struct dropmsgstrings *wentry;
 
    for (rentry = dropmsgstringarray; rentry->kind != '\0'; rentry++)
        if (rentry->kind == rightkind)
            break;
    Assert(rentry->kind != '\0');
 
    for (wentry = dropmsgstringarray; wentry->kind != '\0'; wentry++)
        if (wentry->kind == wrongkind)
            break;
    /* wrongkind could be something we don't have in our table... */
 
    ereport(ERROR,
            (errcode(ERRCODE_WRONG_OBJECT_TYPE),
             errmsg(rentry->nota_msg, relname),
             (wentry->kind != '\0') ? errhint("%s", _(wentry->drophint_msg)) : 0));
}
 
/*
 * RemoveRelations
 *      Implements DROP TABLE, DROP INDEX, DROP SEQUENCE, DROP VIEW,
 *      DROP MATERIALIZED VIEW, DROP FOREIGN TABLE
 */
void
RemoveRelations(DropStmt *drop)
{
    ObjectAddresses *objects;
    char        relkind;
    ListCell   *cell;
    int         flags = 0;
    LOCKMODE    lockmode = AccessExclusiveLock;
 
    /* DROP CONCURRENTLY uses a weaker lock, and has some restrictions */
    if (drop->concurrent)
    {
        /*
         * Note that for temporary relations this lock may get upgraded later
         * on, but as no other session can access a temporary relation, this
         * is actually fine.
         */
        lockmode = ShareUpdateExclusiveLock;
        Assert(drop->removeType == OBJECT_INDEX);
        if (list_length(drop->objects) != 1)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("DROP INDEX CONCURRENTLY does not support dropping multiple objects")));
        if (drop->behavior == DROP_CASCADE)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("DROP INDEX CONCURRENTLY does not support CASCADE")));
    }
 
    /*
     * First we identify all the relations, then we delete them in a single
     * performMultipleDeletions() call.  This is to avoid unwanted DROP
     * RESTRICT errors if one of the relations depends on another.
     */
 
    /* Determine required relkind */
    switch (drop->removeType)
    {
        case OBJECT_TABLE:
            relkind = RELKIND_RELATION;
            break;
 
        case OBJECT_INDEX:
            relkind = RELKIND_INDEX;
            break;
 
        case OBJECT_SEQUENCE:
            relkind = RELKIND_SEQUENCE;
            break;
 
        case OBJECT_VIEW:
            relkind = RELKIND_VIEW;
            break;
 
        case OBJECT_MATVIEW:
            relkind = RELKIND_MATVIEW;
            break;
 
        case OBJECT_FOREIGN_TABLE:
            relkind = RELKIND_FOREIGN_TABLE;
            break;
 
        default:
            elog(ERROR, "unrecognized drop object type: %d",
                 (int) drop->removeType);
            relkind = 0;        /* keep compiler quiet */
            break;
    }
 
    /* Lock and validate each relation; build a list of object addresses */
    objects = new_object_addresses();
 
    foreach(cell, drop->objects)
    {
        RangeVar   *rel = makeRangeVarFromNameList((List *) lfirst(cell));
        Oid         relOid;
        ObjectAddress obj;
        struct DropRelationCallbackState state;
 
        /*
         * These next few steps are a great deal like relation_openrv, but we
         * don't bother building a relcache entry since we don't need it.
         *
         * Check for shared-cache-inval messages before trying to access the
         * relation.  This is needed to cover the case where the name
         * identifies a rel that has been dropped and recreated since the
         * start of our transaction: if we don't flush the old syscache entry,
         * then we'll latch onto that entry and suffer an error later.
         */
        AcceptInvalidationMessages();
 
        /* Look up the appropriate relation using namespace search. */
        state.expected_relkind = relkind;
        state.heap_lockmode = drop->concurrent ?
            ShareUpdateExclusiveLock : AccessExclusiveLock;
        /* We must initialize these fields to show that no locks are held: */
        state.heapOid = InvalidOid;
        state.partParentOid = InvalidOid;
 
        relOid = RangeVarGetRelidExtended(rel, lockmode, RVR_MISSING_OK,
                                          RangeVarCallbackForDropRelation,
                                          (void *) &state);
 
        /* Not there? */
        if (!OidIsValid(relOid))
        {
            DropErrorMsgNonExistent(rel, relkind, drop->missing_ok);
            continue;
        }
 
        /*
         * Decide if concurrent mode needs to be used here or not.  The
         * callback retrieved the rel's persistence for us.
         */
        if (drop->concurrent &&
            state.actual_relpersistence != RELPERSISTENCE_TEMP)
        {
            Assert(list_length(drop->objects) == 1 &&
                   drop->removeType == OBJECT_INDEX);
            flags |= PERFORM_DELETION_CONCURRENTLY;
        }
 
        /*
         * Concurrent index drop cannot be used with partitioned indexes,
         * either.
         */
        if ((flags & PERFORM_DELETION_CONCURRENTLY) != 0 &&
            state.actual_relkind == RELKIND_PARTITIONED_INDEX)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot drop partitioned index \"%s\" concurrently",
                            rel->relname)));
 
        /*
         * If we're told to drop a partitioned index, we must acquire lock on
         * all the children of its parent partitioned table before proceeding.
         * Otherwise we'd try to lock the child index partitions before their
         * tables, leading to potential deadlock against other sessions that
         * will lock those objects in the other order.
         */
        if (state.actual_relkind == RELKIND_PARTITIONED_INDEX)
            (void) find_all_inheritors(state.heapOid,
                                       state.heap_lockmode,
                                       NULL);
 
        /* OK, we're ready to delete this one */
        obj.classId = RelationRelationId;
        obj.objectId = relOid;
        obj.objectSubId = 0;
 
        add_exact_object_address(&obj, objects);
    }
 
    performMultipleDeletions(objects, drop->behavior, flags);
 
    free_object_addresses(objects);
}
 
/*
 * Before acquiring a table lock, check whether we have sufficient rights.
 * In the case of DROP INDEX, also try to lock the table before the index.
 * Also, if the table to be dropped is a partition, we try to lock the parent
 * first.
 */
static void
RangeVarCallbackForDropRelation(const RangeVar *rel, Oid relOid, Oid oldRelOid,
                                void *arg)
{
    HeapTuple   tuple;
    struct DropRelationCallbackState *state;
    char        expected_relkind;
    bool        is_partition;
    Form_pg_class classform;
    LOCKMODE    heap_lockmode;
    bool        invalid_system_index = false;
 
    state = (struct DropRelationCallbackState *) arg;
    heap_lockmode = state->heap_lockmode;
 
    /*
     * If we previously locked some other index's heap, and the name we're
     * looking up no longer refers to that relation, release the now-useless
     * lock.
     */
    if (relOid != oldRelOid && OidIsValid(state->heapOid))
    {
        UnlockRelationOid(state->heapOid, heap_lockmode);
        state->heapOid = InvalidOid;
    }
 
    /*
     * Similarly, if we previously locked some other partition's heap, and the
     * name we're looking up no longer refers to that relation, release the
     * now-useless lock.
     */
    if (relOid != oldRelOid && OidIsValid(state->partParentOid))
    {
        UnlockRelationOid(state->partParentOid, AccessExclusiveLock);
        state->partParentOid = InvalidOid;
    }
 
    /* Didn't find a relation, so no need for locking or permission checks. */
    if (!OidIsValid(relOid))
        return;
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relOid));
    if (!HeapTupleIsValid(tuple))
        return;                 /* concurrently dropped, so nothing to do */
    classform = (Form_pg_class) GETSTRUCT(tuple);
    is_partition = classform->relispartition;
 
    /* Pass back some data to save lookups in RemoveRelations */
    state->actual_relkind = classform->relkind;
    state->actual_relpersistence = classform->relpersistence;
 
    /*
     * Both RELKIND_RELATION and RELKIND_PARTITIONED_TABLE are OBJECT_TABLE,
     * but RemoveRelations() can only pass one relkind for a given relation.
     * It chooses RELKIND_RELATION for both regular and partitioned tables.
     * That means we must be careful before giving the wrong type error when
     * the relation is RELKIND_PARTITIONED_TABLE.  An equivalent problem
     * exists with indexes.
     */
    if (classform->relkind == RELKIND_PARTITIONED_TABLE)
        expected_relkind = RELKIND_RELATION;
    else if (classform->relkind == RELKIND_PARTITIONED_INDEX)
        expected_relkind = RELKIND_INDEX;
    else
        expected_relkind = classform->relkind;
 
    if (state->expected_relkind != expected_relkind)
        DropErrorMsgWrongType(rel->relname, classform->relkind,
                              state->expected_relkind);
 
    /* Allow DROP to either table owner or schema owner */
    if (!object_ownercheck(RelationRelationId, relOid, GetUserId()) &&
        !object_ownercheck(NamespaceRelationId, classform->relnamespace, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER,
                       get_relkind_objtype(classform->relkind),
                       rel->relname);
 
    /*
     * Check the case of a system index that might have been invalidated by a
     * failed concurrent process and allow its drop. For the time being, this
     * only concerns indexes of toast relations that became invalid during a
     * REINDEX CONCURRENTLY process.
     */
    if (IsSystemClass(relOid, classform) && classform->relkind == RELKIND_INDEX)
    {
        HeapTuple   locTuple;
        Form_pg_index indexform;
        bool        indisvalid;
 
        locTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(relOid));
        if (!HeapTupleIsValid(locTuple))
        {
            ReleaseSysCache(tuple);
            return;
        }
 
        indexform = (Form_pg_index) GETSTRUCT(locTuple);
        indisvalid = indexform->indisvalid;
        ReleaseSysCache(locTuple);
 
        /* Mark object as being an invalid index of system catalogs */
        if (!indisvalid)
            invalid_system_index = true;
    }
 
    /* In the case of an invalid index, it is fine to bypass this check */
    if (!invalid_system_index && !allowSystemTableMods && IsSystemClass(relOid, classform))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: \"%s\" is a system catalog",
                        rel->relname)));
 
    ReleaseSysCache(tuple);
 
    /*
     * In DROP INDEX, attempt to acquire lock on the parent table before
     * locking the index.  index_drop() will need this anyway, and since
     * regular queries lock tables before their indexes, we risk deadlock if
     * we do it the other way around.  No error if we don't find a pg_index
     * entry, though --- the relation may have been dropped.  Note that this
     * code will execute for either plain or partitioned indexes.
     */
    if (expected_relkind == RELKIND_INDEX &&
        relOid != oldRelOid)
    {
        state->heapOid = IndexGetRelation(relOid, true);
        if (OidIsValid(state->heapOid))
            LockRelationOid(state->heapOid, heap_lockmode);
    }
 
    /*
     * Similarly, if the relation is a partition, we must acquire lock on its
     * parent before locking the partition.  That's because queries lock the
     * parent before its partitions, so we risk deadlock if we do it the other
     * way around.
     */
    if (is_partition && relOid != oldRelOid)
    {
        state->partParentOid = get_partition_parent(relOid, true);
        if (OidIsValid(state->partParentOid))
            LockRelationOid(state->partParentOid, AccessExclusiveLock);
    }
}
 
/*
 * ExecuteTruncate
 *      Executes a TRUNCATE command.
 *
 * This is a multi-relation truncate.  We first open and grab exclusive
 * lock on all relations involved, checking permissions and otherwise
 * verifying that the relation is OK for truncation.  Note that if relations
 * are foreign tables, at this stage, we have not yet checked that their
 * foreign data in external data sources are OK for truncation.  These are
 * checked when foreign data are actually truncated later.  In CASCADE mode,
 * relations having FK references to the targeted relations are automatically
 * added to the group; in RESTRICT mode, we check that all FK references are
 * internal to the group that's being truncated.  Finally all the relations
 * are truncated and reindexed.
 */
void
ExecuteTruncate(TruncateStmt *stmt)
{
    List       *rels = NIL;
    List       *relids = NIL;
    List       *relids_logged = NIL;
    ListCell   *cell;
 
    /*
     * Open, exclusive-lock, and check all the explicitly-specified relations
     */
    foreach(cell, stmt->relations)
    {
        RangeVar   *rv = lfirst(cell);
        Relation    rel;
        bool        recurse = rv->inh;
        Oid         myrelid;
        LOCKMODE    lockmode = AccessExclusiveLock;
 
        myrelid = RangeVarGetRelidExtended(rv, lockmode,
                                           0, RangeVarCallbackForTruncate,
                                           NULL);
 
        /* don't throw error for "TRUNCATE foo, foo" */
        if (list_member_oid(relids, myrelid))
            continue;
 
        /* open the relation, we already hold a lock on it */
        rel = table_open(myrelid, NoLock);
 
        /*
         * RangeVarGetRelidExtended() has done most checks with its callback,
         * but other checks with the now-opened Relation remain.
         */
        truncate_check_activity(rel);
 
        rels = lappend(rels, rel);
        relids = lappend_oid(relids, myrelid);
 
        /* Log this relation only if needed for logical decoding */
        if (RelationIsLogicallyLogged(rel))
            relids_logged = lappend_oid(relids_logged, myrelid);
 
        if (recurse)
        {
            ListCell   *child;
            List       *children;
 
            children = find_all_inheritors(myrelid, lockmode, NULL);
 
            foreach(child, children)
            {
                Oid         childrelid = lfirst_oid(child);
 
                if (list_member_oid(relids, childrelid))
                    continue;
 
                /* find_all_inheritors already got lock */
                rel = table_open(childrelid, NoLock);
 
                /*
                 * It is possible that the parent table has children that are
                 * temp tables of other backends.  We cannot safely access
                 * such tables (because of buffering issues), and the best
                 * thing to do is to silently ignore them.  Note that this
                 * check is the same as one of the checks done in
                 * truncate_check_activity() called below, still it is kept
                 * here for simplicity.
                 */
                if (RELATION_IS_OTHER_TEMP(rel))
                {
                    table_close(rel, lockmode);
                    continue;
                }
 
                /*
                 * Inherited TRUNCATE commands perform access permission
                 * checks on the parent table only. So we skip checking the
                 * children's permissions and don't call
                 * truncate_check_perms() here.
                 */
                truncate_check_rel(RelationGetRelid(rel), rel->rd_rel);
                truncate_check_activity(rel);
 
                rels = lappend(rels, rel);
                relids = lappend_oid(relids, childrelid);
 
                /* Log this relation only if needed for logical decoding */
                if (RelationIsLogicallyLogged(rel))
                    relids_logged = lappend_oid(relids_logged, childrelid);
            }
        }
        else if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot truncate only a partitioned table"),
                     errhint("Do not specify the ONLY keyword, or use TRUNCATE ONLY on the partitions directly.")));
    }
 
    ExecuteTruncateGuts(rels, relids, relids_logged,
                        stmt->behavior, stmt->restart_seqs, false);
 
    /* And close the rels */
    foreach(cell, rels)
    {
        Relation    rel = (Relation) lfirst(cell);
 
        table_close(rel, NoLock);
    }
}
 
/*
 * ExecuteTruncateGuts
 *
 * Internal implementation of TRUNCATE.  This is called by the actual TRUNCATE
 * command (see above) as well as replication subscribers that execute a
 * replicated TRUNCATE action.
 *
 * explicit_rels is the list of Relations to truncate that the command
 * specified.  relids is the list of Oids corresponding to explicit_rels.
 * relids_logged is the list of Oids (a subset of relids) that require
 * WAL-logging.  This is all a bit redundant, but the existing callers have
 * this information handy in this form.
 */
void
ExecuteTruncateGuts(List *explicit_rels,
                    List *relids,
                    List *relids_logged,
                    DropBehavior behavior, bool restart_seqs,
                    bool run_as_table_owner)
{
    List       *rels;
    List       *seq_relids = NIL;
    HTAB       *ft_htab = NULL;
    EState     *estate;
    ResultRelInfo *resultRelInfos;
    ResultRelInfo *resultRelInfo;
    SubTransactionId mySubid;
    ListCell   *cell;
    Oid        *logrelids;
 
    /*
     * Check the explicitly-specified relations.
     *
     * In CASCADE mode, suck in all referencing relations as well.  This
     * requires multiple iterations to find indirectly-dependent relations. At
     * each phase, we need to exclusive-lock new rels before looking for their
     * dependencies, else we might miss something.  Also, we check each rel as
     * soon as we open it, to avoid a faux pas such as holding lock for a long
     * time on a rel we have no permissions for.
     */
    rels = list_copy(explicit_rels);
    if (behavior == DROP_CASCADE)
    {
        for (;;)
        {
            List       *newrelids;
 
            newrelids = heap_truncate_find_FKs(relids);
            if (newrelids == NIL)
                break;          /* nothing else to add */
 
            foreach(cell, newrelids)
            {
                Oid         relid = lfirst_oid(cell);
                Relation    rel;
 
                rel = table_open(relid, AccessExclusiveLock);
                ereport(NOTICE,
                        (errmsg("truncate cascades to table \"%s\"",
                                RelationGetRelationName(rel))));
                truncate_check_rel(relid, rel->rd_rel);
                truncate_check_perms(relid, rel->rd_rel);
                truncate_check_activity(rel);
                rels = lappend(rels, rel);
                relids = lappend_oid(relids, relid);
 
                /* Log this relation only if needed for logical decoding */
                if (RelationIsLogicallyLogged(rel))
                    relids_logged = lappend_oid(relids_logged, relid);
            }
        }
    }
 
    /*
     * Check foreign key references.  In CASCADE mode, this should be
     * unnecessary since we just pulled in all the references; but as a
     * cross-check, do it anyway if in an Assert-enabled build.
     */
#ifdef USE_ASSERT_CHECKING
    heap_truncate_check_FKs(rels, false);
#else
    if (behavior == DROP_RESTRICT)
        heap_truncate_check_FKs(rels, false);
#endif
 
    /*
     * If we are asked to restart sequences, find all the sequences, lock them
     * (we need AccessExclusiveLock for ResetSequence), and check permissions.
     * We want to do this early since it's pointless to do all the truncation
     * work only to fail on sequence permissions.
     */
    if (restart_seqs)
    {
        foreach(cell, rels)
        {
            Relation    rel = (Relation) lfirst(cell);
            List       *seqlist = getOwnedSequences(RelationGetRelid(rel));
            ListCell   *seqcell;
 
            foreach(seqcell, seqlist)
            {
                Oid         seq_relid = lfirst_oid(seqcell);
                Relation    seq_rel;
 
                seq_rel = relation_open(seq_relid, AccessExclusiveLock);
 
                /* This check must match AlterSequence! */
                if (!object_ownercheck(RelationRelationId, seq_relid, GetUserId()))
                    aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SEQUENCE,
                                   RelationGetRelationName(seq_rel));
 
                seq_relids = lappend_oid(seq_relids, seq_relid);
 
                relation_close(seq_rel, NoLock);
            }
        }
    }
 
    /* Prepare to catch AFTER triggers. */
    AfterTriggerBeginQuery();
 
    /*
     * To fire triggers, we'll need an EState as well as a ResultRelInfo for
     * each relation.  We don't need to call ExecOpenIndices, though.
     *
     * We put the ResultRelInfos in the es_opened_result_relations list, even
     * though we don't have a range table and don't populate the
     * es_result_relations array.  That's a bit bogus, but it's enough to make
     * ExecGetTriggerResultRel() find them.
     */
    estate = CreateExecutorState();
    resultRelInfos = (ResultRelInfo *)
        palloc(list_length(rels) * sizeof(ResultRelInfo));
    resultRelInfo = resultRelInfos;
    foreach(cell, rels)
    {
        Relation    rel = (Relation) lfirst(cell);
 
        InitResultRelInfo(resultRelInfo,
                          rel,
                          0,    /* dummy rangetable index */
                          NULL,
                          0);
        estate->es_opened_result_relations =
            lappend(estate->es_opened_result_relations, resultRelInfo);
        resultRelInfo++;
    }
 
    /*
     * Process all BEFORE STATEMENT TRUNCATE triggers before we begin
     * truncating (this is because one of them might throw an error). Also, if
     * we were to allow them to prevent statement execution, that would need
     * to be handled here.
     */
    resultRelInfo = resultRelInfos;
    foreach(cell, rels)
    {
        UserContext ucxt;
 
        if (run_as_table_owner)
            SwitchToUntrustedUser(resultRelInfo->ri_RelationDesc->rd_rel->relowner,
                                  &ucxt);
        ExecBSTruncateTriggers(estate, resultRelInfo);
        if (run_as_table_owner)
            RestoreUserContext(&ucxt);
        resultRelInfo++;
    }
 
    /*
     * OK, truncate each table.
     */
    mySubid = GetCurrentSubTransactionId();
 
    foreach(cell, rels)
    {
        Relation    rel = (Relation) lfirst(cell);
 
        /* Skip partitioned tables as there is nothing to do */
        if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
            continue;
 
        /*
         * Build the lists of foreign tables belonging to each foreign server
         * and pass each list to the foreign data wrapper's callback function,
         * so that each server can truncate its all foreign tables in bulk.
         * Each list is saved as a single entry in a hash table that uses the
         * server OID as lookup key.
         */
        if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
        {
            Oid         serverid = GetForeignServerIdByRelId(RelationGetRelid(rel));
            bool        found;
            ForeignTruncateInfo *ft_info;
 
            /* First time through, initialize hashtable for foreign tables */
            if (!ft_htab)
            {
                HASHCTL     hctl;
 
                memset(&hctl, 0, sizeof(HASHCTL));
                hctl.keysize = sizeof(Oid);
                hctl.entrysize = sizeof(ForeignTruncateInfo);
                hctl.hcxt = CurrentMemoryContext;
 
                ft_htab = hash_create("TRUNCATE for Foreign Tables",
                                      32,   /* start small and extend */
                                      &hctl,
                                      HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
            }
 
            /* Find or create cached entry for the foreign table */
            ft_info = hash_search(ft_htab, &serverid, HASH_ENTER, &found);
            if (!found)
                ft_info->rels = NIL;
 
            /*
             * Save the foreign table in the entry of the server that the
             * foreign table belongs to.
             */
            ft_info->rels = lappend(ft_info->rels, rel);
            continue;
        }
 
        /*
         * Normally, we need a transaction-safe truncation here.  However, if
         * the table was either created in the current (sub)transaction or has
         * a new relfilenumber in the current (sub)transaction, then we can
         * just truncate it in-place, because a rollback would cause the whole
         * table or the current physical file to be thrown away anyway.
         */
        if (rel->rd_createSubid == mySubid ||
            rel->rd_newRelfilelocatorSubid == mySubid)
        {
            /* Immediate, non-rollbackable truncation is OK */
            heap_truncate_one_rel(rel);
        }
        else
        {
            Oid         heap_relid;
            Oid         toast_relid;
            ReindexParams reindex_params = {0};
 
            /*
             * This effectively deletes all rows in the table, and may be done
             * in a serializable transaction.  In that case we must record a
             * rw-conflict in to this transaction from each transaction
             * holding a predicate lock on the table.
             */
            CheckTableForSerializableConflictIn(rel);
 
            /*
             * Need the full transaction-safe pushups.
             *
             * Create a new empty storage file for the relation, and assign it
             * as the relfilenumber value. The old storage file is scheduled
             * for deletion at commit.
             */
            RelationSetNewRelfilenumber(rel, rel->rd_rel->relpersistence);
 
            heap_relid = RelationGetRelid(rel);
 
            /*
             * The same for the toast table, if any.
             */
            toast_relid = rel->rd_rel->reltoastrelid;
            if (OidIsValid(toast_relid))
            {
                Relation    toastrel = relation_open(toast_relid,
                                                     AccessExclusiveLock);
 
                RelationSetNewRelfilenumber(toastrel,
                                            toastrel->rd_rel->relpersistence);
                table_close(toastrel, NoLock);
            }
 
            /*
             * Reconstruct the indexes to match, and we're done.
             */
            reindex_relation(NULL, heap_relid, REINDEX_REL_PROCESS_TOAST,
                             &reindex_params);
        }
 
        pgstat_count_truncate(rel);
    }
 
    /* Now go through the hash table, and truncate foreign tables */
    if (ft_htab)
    {
        ForeignTruncateInfo *ft_info;
        HASH_SEQ_STATUS seq;
 
        hash_seq_init(&seq, ft_htab);
 
        PG_TRY();
        {
            while ((ft_info = hash_seq_search(&seq)) != NULL)
            {
                FdwRoutine *routine = GetFdwRoutineByServerId(ft_info->serverid);
 
                /* truncate_check_rel() has checked that already */
                Assert(routine->ExecForeignTruncate != NULL);
 
                routine->ExecForeignTruncate(ft_info->rels,
                                             behavior,
                                             restart_seqs);
            }
        }
        PG_FINALLY();
        {
            hash_destroy(ft_htab);
        }
        PG_END_TRY();
    }
 
    /*
     * Restart owned sequences if we were asked to.
     */
    foreach(cell, seq_relids)
    {
        Oid         seq_relid = lfirst_oid(cell);
 
        ResetSequence(seq_relid);
    }
 
    /*
     * Write a WAL record to allow this set of actions to be logically
     * decoded.
     *
     * Assemble an array of relids so we can write a single WAL record for the
     * whole action.
     */
    if (relids_logged != NIL)
    {
        xl_heap_truncate xlrec;
        int         i = 0;
 
        /* should only get here if wal_level >= logical */
        Assert(XLogLogicalInfoActive());
 
        logrelids = palloc(list_length(relids_logged) * sizeof(Oid));
        foreach(cell, relids_logged)
            logrelids[i++] = lfirst_oid(cell);
 
        xlrec.dbId = MyDatabaseId;
        xlrec.nrelids = list_length(relids_logged);
        xlrec.flags = 0;
        if (behavior == DROP_CASCADE)
            xlrec.flags |= XLH_TRUNCATE_CASCADE;
        if (restart_seqs)
            xlrec.flags |= XLH_TRUNCATE_RESTART_SEQS;
 
        XLogBeginInsert();
        XLogRegisterData((char *) &xlrec, SizeOfHeapTruncate);
        XLogRegisterData((char *) logrelids, list_length(relids_logged) * sizeof(Oid));
 
        XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN);
 
        (void) XLogInsert(RM_HEAP_ID, XLOG_HEAP_TRUNCATE);
    }
 
    /*
     * Process all AFTER STATEMENT TRUNCATE triggers.
     */
    resultRelInfo = resultRelInfos;
    foreach(cell, rels)
    {
        UserContext ucxt;
 
        if (run_as_table_owner)
            SwitchToUntrustedUser(resultRelInfo->ri_RelationDesc->rd_rel->relowner,
                                  &ucxt);
        ExecASTruncateTriggers(estate, resultRelInfo);
        if (run_as_table_owner)
            RestoreUserContext(&ucxt);
        resultRelInfo++;
    }
 
    /* Handle queued AFTER triggers */
    AfterTriggerEndQuery(estate);
 
    /* We can clean up the EState now */
    FreeExecutorState(estate);
 
    /*
     * Close any rels opened by CASCADE (can't do this while EState still
     * holds refs)
     */
    rels = list_difference_ptr(rels, explicit_rels);
    foreach(cell, rels)
    {
        Relation    rel = (Relation) lfirst(cell);
 
        table_close(rel, NoLock);
    }
}
 
/*
 * Check that a given relation is safe to truncate.  Subroutine for
 * ExecuteTruncate() and RangeVarCallbackForTruncate().
 */
static void
truncate_check_rel(Oid relid, Form_pg_class reltuple)
{
    char       *relname = NameStr(reltuple->relname);
 
    /*
     * Only allow truncate on regular tables, foreign tables using foreign
     * data wrappers supporting TRUNCATE and partitioned tables (although, the
     * latter are only being included here for the following checks; no
     * physical truncation will occur in their case.).
     */
    if (reltuple->relkind == RELKIND_FOREIGN_TABLE)
    {
        Oid         serverid = GetForeignServerIdByRelId(relid);
        FdwRoutine *fdwroutine = GetFdwRoutineByServerId(serverid);
 
        if (!fdwroutine->ExecForeignTruncate)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot truncate foreign table \"%s\"",
                            relname)));
    }
    else if (reltuple->relkind != RELKIND_RELATION &&
             reltuple->relkind != RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a table", relname)));
 
    /*
     * Most system catalogs can't be truncated at all, or at least not unless
     * allow_system_table_mods=on. As an exception, however, we allow
     * pg_largeobject to be truncated as part of pg_upgrade, because we need
     * to change its relfilenode to match the old cluster, and allowing a
     * TRUNCATE command to be executed is the easiest way of doing that.
     */
    if (!allowSystemTableMods && IsSystemClass(relid, reltuple)
        && (!IsBinaryUpgrade || relid != LargeObjectRelationId))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: \"%s\" is a system catalog",
                        relname)));
 
    InvokeObjectTruncateHook(relid);
}
 
/*
 * Check that current user has the permission to truncate given relation.
 */
static void
truncate_check_perms(Oid relid, Form_pg_class reltuple)
{
    char       *relname = NameStr(reltuple->relname);
    AclResult   aclresult;
 
    /* Permissions checks */
    aclresult = pg_class_aclcheck(relid, GetUserId(), ACL_TRUNCATE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, get_relkind_objtype(reltuple->relkind),
                       relname);
}
 
/*
 * Set of extra sanity checks to check if a given relation is safe to
 * truncate.  This is split with truncate_check_rel() as
 * RangeVarCallbackForTruncate() cannot open a Relation yet.
 */
static void
truncate_check_activity(Relation rel)
{
    /*
     * Don't allow truncate on temp tables of other backends ... their local
     * buffer manager is not going to cope.
     */
    if (RELATION_IS_OTHER_TEMP(rel))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot truncate temporary tables of other sessions")));
 
    /*
     * Also check for active uses of the relation in the current transaction,
     * including open scans and pending AFTER trigger events.
     */
    CheckTableNotInUse(rel, "TRUNCATE");
}
 
/*
 * storage_name
 *    returns the name corresponding to a typstorage/attstorage enum value
 */
static const char *
storage_name(char c)
{
    switch (c)
    {
        case TYPSTORAGE_PLAIN:
            return "PLAIN";
        case TYPSTORAGE_EXTERNAL:
            return "EXTERNAL";
        case TYPSTORAGE_EXTENDED:
            return "EXTENDED";
        case TYPSTORAGE_MAIN:
            return "MAIN";
        default:
            return "???";
    }
}
 
/*----------
 * MergeAttributes
 *      Returns new schema given initial schema and superclasses.
 *
 * Input arguments:
 * 'columns' is the column/attribute definition for the table. (It's a list
 *      of ColumnDef's.) It is destructively changed.
 * 'supers' is a list of OIDs of parent relations, already locked by caller.
 * 'relpersistence' is the persistence type of the table.
 * 'is_partition' tells if the table is a partition.
 *
 * Output arguments:
 * 'supconstr' receives a list of constraints belonging to the parents,
 *      updated as necessary to be valid for the child.
 *
 * Return value:
 * Completed schema list.
 *
 * Notes:
 *    The order in which the attributes are inherited is very important.
 *    Intuitively, the inherited attributes should come first. If a table
 *    inherits from multiple parents, the order of those attributes are
 *    according to the order of the parents specified in CREATE TABLE.
 *
 *    Here's an example:
 *
 *      create table person (name text, age int4, location point);
 *      create table emp (salary int4, manager text) inherits(person);
 *      create table student (gpa float8) inherits (person);
 *      create table stud_emp (percent int4) inherits (emp, student);
 *
 *    The order of the attributes of stud_emp is:
 *
 *                          person {1:name, 2:age, 3:location}
 *                          /    \
 *             {6:gpa}  student   emp {4:salary, 5:manager}
 *                          \    /
 *                         stud_emp {7:percent}
 *
 *     If the same attribute name appears multiple times, then it appears
 *     in the result table in the proper location for its first appearance.
 *
 *     Constraints (including not-null constraints) for the child table
 *     are the union of all relevant constraints, from both the child schema
 *     and parent tables.
 *
 *     The default value for a child column is defined as:
 *      (1) If the child schema specifies a default, that value is used.
 *      (2) If neither the child nor any parent specifies a default, then
 *          the column will not have a default.
 *      (3) If conflicting defaults are inherited from different parents
 *          (and not overridden by the child), an error is raised.
 *      (4) Otherwise the inherited default is used.
 *
 *      Note that the default-value infrastructure is used for generated
 *      columns' expressions too, so most of the preceding paragraph applies
 *      to generation expressions too.  We insist that a child column be
 *      generated if and only if its parent(s) are, but it need not have
 *      the same generation expression.
 *----------
 */
static List *
MergeAttributes(List *columns, const List *supers, char relpersistence,
                bool is_partition, List **supconstr)
{
    List       *inh_columns = NIL;
    List       *constraints = NIL;
    bool        have_bogus_defaults = false;
    int         child_attno;
    static Node bogus_marker = {0}; /* marks conflicting defaults */
    List       *saved_columns = NIL;
    ListCell   *lc;
 
    /*
     * Check for and reject tables with too many columns. We perform this
     * check relatively early for two reasons: (a) we don't run the risk of
     * overflowing an AttrNumber in subsequent code (b) an O(n^2) algorithm is
     * okay if we're processing <= 1600 columns, but could take minutes to
     * execute if the user attempts to create a table with hundreds of
     * thousands of columns.
     *
     * Note that we also need to check that we do not exceed this figure after
     * including columns from inherited relations.
     */
    if (list_length(columns) > MaxHeapAttributeNumber)
        ereport(ERROR,
                (errcode(ERRCODE_TOO_MANY_COLUMNS),
                 errmsg("tables can have at most %d columns",
                        MaxHeapAttributeNumber)));
 
    /*
     * Check for duplicate names in the explicit list of attributes.
     *
     * Although we might consider merging such entries in the same way that we
     * handle name conflicts for inherited attributes, it seems to make more
     * sense to assume such conflicts are errors.
     *
     * We don't use foreach() here because we have two nested loops over the
     * columns list, with possible element deletions in the inner one.  If we
     * used foreach_delete_current() it could only fix up the state of one of
     * the loops, so it seems cleaner to use looping over list indexes for
     * both loops.  Note that any deletion will happen beyond where the outer
     * loop is, so its index never needs adjustment.
     */
    for (int coldefpos = 0; coldefpos < list_length(columns); coldefpos++)
    {
        ColumnDef  *coldef = list_nth_node(ColumnDef, columns, coldefpos);
 
        if (!is_partition && coldef->typeName == NULL)
        {
            /*
             * Typed table column option that does not belong to a column from
             * the type.  This works because the columns from the type come
             * first in the list.  (We omit this check for partition column
             * lists; those are processed separately below.)
             */
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" does not exist",
                            coldef->colname)));
        }
 
        /* restpos scans all entries beyond coldef; incr is in loop body */
        for (int restpos = coldefpos + 1; restpos < list_length(columns);)
        {
            ColumnDef  *restdef = list_nth_node(ColumnDef, columns, restpos);
 
            if (strcmp(coldef->colname, restdef->colname) == 0)
            {
                if (coldef->is_from_type)
                {
                    /*
                     * merge the column options into the column from the type
                     */
                    coldef->is_not_null = restdef->is_not_null;
                    coldef->raw_default = restdef->raw_default;
                    coldef->cooked_default = restdef->cooked_default;
                    coldef->constraints = restdef->constraints;
                    coldef->is_from_type = false;
                    columns = list_delete_nth_cell(columns, restpos);
                }
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_DUPLICATE_COLUMN),
                             errmsg("column \"%s\" specified more than once",
                                    coldef->colname)));
            }
            else
                restpos++;
        }
    }
 
    /*
     * In case of a partition, there are no new column definitions, only dummy
     * ColumnDefs created for column constraints.  Set them aside for now and
     * process them at the end.
     */
    if (is_partition)
    {
        saved_columns = columns;
        columns = NIL;
    }
 
    /*
     * Scan the parents left-to-right, and merge their attributes to form a
     * list of inherited columns (inh_columns).
     */
    child_attno = 0;
    foreach(lc, supers)
    {
        Oid         parent = lfirst_oid(lc);
        Relation    relation;
        TupleDesc   tupleDesc;
        TupleConstr *constr;
        AttrMap    *newattmap;
        List       *inherited_defaults;
        List       *cols_with_defaults;
        ListCell   *lc1;
        ListCell   *lc2;
 
        /* caller already got lock */
        relation = table_open(parent, NoLock);
 
        /*
         * Check for active uses of the parent partitioned table in the
         * current transaction, such as being used in some manner by an
         * enclosing command.
         */
        if (is_partition)
            CheckTableNotInUse(relation, "CREATE TABLE .. PARTITION OF");
 
        /*
         * We do not allow partitioned tables and partitions to participate in
         * regular inheritance.
         */
        if (relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE && !is_partition)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot inherit from partitioned table \"%s\"",
                            RelationGetRelationName(relation))));
        if (relation->rd_rel->relispartition && !is_partition)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot inherit from partition \"%s\"",
                            RelationGetRelationName(relation))));
 
        if (relation->rd_rel->relkind != RELKIND_RELATION &&
            relation->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
            relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("inherited relation \"%s\" is not a table or foreign table",
                            RelationGetRelationName(relation))));
 
        /*
         * If the parent is permanent, so must be all of its partitions.  Note
         * that inheritance allows that case.
         */
        if (is_partition &&
            relation->rd_rel->relpersistence != RELPERSISTENCE_TEMP &&
            relpersistence == RELPERSISTENCE_TEMP)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot create a temporary relation as partition of permanent relation \"%s\"",
                            RelationGetRelationName(relation))));
 
        /* Permanent rels cannot inherit from temporary ones */
        if (relpersistence != RELPERSISTENCE_TEMP &&
            relation->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg(!is_partition
                            ? "cannot inherit from temporary relation \"%s\""
                            : "cannot create a permanent relation as partition of temporary relation \"%s\"",
                            RelationGetRelationName(relation))));
 
        /* If existing rel is temp, it must belong to this session */
        if (relation->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
            !relation->rd_islocaltemp)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg(!is_partition
                            ? "cannot inherit from temporary relation of another session"
                            : "cannot create as partition of temporary relation of another session")));
 
        /*
         * We should have an UNDER permission flag for this, but for now,
         * demand that creator of a child table own the parent.
         */
        if (!object_ownercheck(RelationRelationId, RelationGetRelid(relation), GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(relation->rd_rel->relkind),
                           RelationGetRelationName(relation));
 
        tupleDesc = RelationGetDescr(relation);
        constr = tupleDesc->constr;
 
        /*
         * newattmap->attnums[] will contain the child-table attribute numbers
         * for the attributes of this parent table.  (They are not the same
         * for parents after the first one, nor if we have dropped columns.)
         */
        newattmap = make_attrmap(tupleDesc->natts);
 
        /* We can't process inherited defaults until newattmap is complete. */
        inherited_defaults = cols_with_defaults = NIL;
 
        for (AttrNumber parent_attno = 1; parent_attno <= tupleDesc->natts;
             parent_attno++)
        {
            Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
                                                        parent_attno - 1);
            char       *attributeName = NameStr(attribute->attname);
            int         exist_attno;
            ColumnDef  *newdef;
            ColumnDef  *mergeddef;
 
            /*
             * Ignore dropped columns in the parent.
             */
            if (attribute->attisdropped)
                continue;       /* leave newattmap->attnums entry as zero */
 
            /*
             * Create new column definition
             */
            newdef = makeColumnDef(attributeName, attribute->atttypid,
                                   attribute->atttypmod, attribute->attcollation);
            newdef->is_not_null = attribute->attnotnull;
            newdef->storage = attribute->attstorage;
            newdef->generated = attribute->attgenerated;
            if (CompressionMethodIsValid(attribute->attcompression))
                newdef->compression =
                    pstrdup(GetCompressionMethodName(attribute->attcompression));
 
            /*
             * Regular inheritance children are independent enough not to
             * inherit identity columns.  But partitions are integral part of
             * a partitioned table and inherit identity column.
             */
            if (is_partition)
                newdef->identity = attribute->attidentity;
 
            /*
             * Does it match some previously considered column from another
             * parent?
             */
            exist_attno = findAttrByName(attributeName, inh_columns);
            if (exist_attno > 0)
            {
                /*
                 * Yes, try to merge the two column definitions.
                 */
                mergeddef = MergeInheritedAttribute(inh_columns, exist_attno, newdef);
 
                newattmap->attnums[parent_attno - 1] = exist_attno;
 
                /*
                 * Partitions have only one parent, so conflict should never
                 * occur.
                 */
                Assert(!is_partition);
            }
            else
            {
                /*
                 * No, create a new inherited column
                 */
                newdef->inhcount = 1;
                newdef->is_local = false;
                inh_columns = lappend(inh_columns, newdef);
 
                newattmap->attnums[parent_attno - 1] = ++child_attno;
                mergeddef = newdef;
            }
 
            /*
             * Locate default/generation expression if any
             */
            if (attribute->atthasdef)
            {
                Node       *this_default;
 
                this_default = TupleDescGetDefault(tupleDesc, parent_attno);
                if (this_default == NULL)
                    elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
                         parent_attno, RelationGetRelationName(relation));
 
                /*
                 * If it's a GENERATED default, it might contain Vars that
                 * need to be mapped to the inherited column(s)' new numbers.
                 * We can't do that till newattmap is ready, so just remember
                 * all the inherited default expressions for the moment.
                 */
                inherited_defaults = lappend(inherited_defaults, this_default);
                cols_with_defaults = lappend(cols_with_defaults, mergeddef);
            }
        }
 
        /*
         * Now process any inherited default expressions, adjusting attnos
         * using the completed newattmap map.
         */
        forboth(lc1, inherited_defaults, lc2, cols_with_defaults)
        {
            Node       *this_default = (Node *) lfirst(lc1);
            ColumnDef  *def = (ColumnDef *) lfirst(lc2);
            bool        found_whole_row;
 
            /* Adjust Vars to match new table's column numbering */
            this_default = map_variable_attnos(this_default,
                                               1, 0,
                                               newattmap,
                                               InvalidOid, &found_whole_row);
 
            /*
             * For the moment we have to reject whole-row variables.  We could
             * convert them, if we knew the new table's rowtype OID, but that
             * hasn't been assigned yet.  (A variable could only appear in a
             * generation expression, so the error message is correct.)
             */
            if (found_whole_row)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot convert whole-row table reference"),
                         errdetail("Generation expression for column \"%s\" contains a whole-row reference to table \"%s\".",
                                   def->colname,
                                   RelationGetRelationName(relation))));
 
            /*
             * If we already had a default from some prior parent, check to
             * see if they are the same.  If so, no problem; if not, mark the
             * column as having a bogus default.  Below, we will complain if
             * the bogus default isn't overridden by the child columns.
             */
            Assert(def->raw_default == NULL);
            if (def->cooked_default == NULL)
                def->cooked_default = this_default;
            else if (!equal(def->cooked_default, this_default))
            {
                def->cooked_default = &bogus_marker;
                have_bogus_defaults = true;
            }
        }
 
        /*
         * Now copy the CHECK constraints of this parent, adjusting attnos
         * using the completed newattmap map.  Identically named constraints
         * are merged if possible, else we throw error.
         */
        if (constr && constr->num_check > 0)
        {
            ConstrCheck *check = constr->check;
 
            for (int i = 0; i < constr->num_check; i++)
            {
                char       *name = check[i].ccname;
                Node       *expr;
                bool        found_whole_row;
 
                /* ignore if the constraint is non-inheritable */
                if (check[i].ccnoinherit)
                    continue;
 
                /* Adjust Vars to match new table's column numbering */
                expr = map_variable_attnos(stringToNode(check[i].ccbin),
                                           1, 0,
                                           newattmap,
                                           InvalidOid, &found_whole_row);
 
                /*
                 * For the moment we have to reject whole-row variables. We
                 * could convert them, if we knew the new table's rowtype OID,
                 * but that hasn't been assigned yet.
                 */
                if (found_whole_row)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot convert whole-row table reference"),
                             errdetail("Constraint \"%s\" contains a whole-row reference to table \"%s\".",
                                       name,
                                       RelationGetRelationName(relation))));
 
                constraints = MergeCheckConstraint(constraints, name, expr);
            }
        }
 
        free_attrmap(newattmap);
 
        /*
         * Close the parent rel, but keep our lock on it until xact commit.
         * That will prevent someone else from deleting or ALTERing the parent
         * before the child is committed.
         */
        table_close(relation, NoLock);
    }
 
    /*
     * If we had no inherited attributes, the result columns are just the
     * explicitly declared columns.  Otherwise, we need to merge the declared
     * columns into the inherited column list.  Although, we never have any
     * explicitly declared columns if the table is a partition.
     */
    if (inh_columns != NIL)
    {
        int         newcol_attno = 0;
 
        foreach(lc, columns)
        {
            ColumnDef  *newdef = lfirst_node(ColumnDef, lc);
            char       *attributeName = newdef->colname;
            int         exist_attno;
 
            /*
             * Partitions have only one parent and have no column definitions
             * of their own, so conflict should never occur.
             */
            Assert(!is_partition);
 
            newcol_attno++;
 
            /*
             * Does it match some inherited column?
             */
            exist_attno = findAttrByName(attributeName, inh_columns);
            if (exist_attno > 0)
            {
                /*
                 * Yes, try to merge the two column definitions.
                 */
                MergeChildAttribute(inh_columns, exist_attno, newcol_attno, newdef);
            }
            else
            {
                /*
                 * No, attach new column unchanged to result columns.
                 */
                inh_columns = lappend(inh_columns, newdef);
            }
        }
 
        columns = inh_columns;
 
        /*
         * Check that we haven't exceeded the legal # of columns after merging
         * in inherited columns.
         */
        if (list_length(columns) > MaxHeapAttributeNumber)
            ereport(ERROR,
                    (errcode(ERRCODE_TOO_MANY_COLUMNS),
                     errmsg("tables can have at most %d columns",
                            MaxHeapAttributeNumber)));
    }
 
    /*
     * Now that we have the column definition list for a partition, we can
     * check whether the columns referenced in the column constraint specs
     * actually exist.  Also, we merge parent's not-null constraints and
     * defaults into each corresponding column definition.
     */
    if (is_partition)
    {
        foreach(lc, saved_columns)
        {
            ColumnDef  *restdef = lfirst(lc);
            bool        found = false;
            ListCell   *l;
 
            foreach(l, columns)
            {
                ColumnDef  *coldef = lfirst(l);
 
                if (strcmp(coldef->colname, restdef->colname) == 0)
                {
                    found = true;
                    coldef->is_not_null |= restdef->is_not_null;
 
                    /*
                     * Check for conflicts related to generated columns.
                     *
                     * Same rules as above: generated-ness has to match the
                     * parent, but the contents of the generation expression
                     * can be different.
                     */
                    if (coldef->generated)
                    {
                        if (restdef->raw_default && !restdef->generated)
                            ereport(ERROR,
                                    (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                                     errmsg("column \"%s\" inherits from generated column but specifies default",
                                            restdef->colname)));
                        if (restdef->identity)
                            ereport(ERROR,
                                    (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                                     errmsg("column \"%s\" inherits from generated column but specifies identity",
                                            restdef->colname)));
                    }
                    else
                    {
                        if (restdef->generated)
                            ereport(ERROR,
                                    (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                                     errmsg("child column \"%s\" specifies generation expression",
                                            restdef->colname),
                                     errhint("A child table column cannot be generated unless its parent column is.")));
                    }
 
                    /*
                     * Override the parent's default value for this column
                     * (coldef->cooked_default) with the partition's local
                     * definition (restdef->raw_default), if there's one. It
                     * should be physically impossible to get a cooked default
                     * in the local definition or a raw default in the
                     * inherited definition, but make sure they're nulls, for
                     * future-proofing.
                     */
                    Assert(restdef->cooked_default == NULL);
                    Assert(coldef->raw_default == NULL);
                    if (restdef->raw_default)
                    {
                        coldef->raw_default = restdef->raw_default;
                        coldef->cooked_default = NULL;
                    }
                }
            }
 
            /* complain for constraints on columns not in parent */
            if (!found)
                ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" does not exist",
                                restdef->colname)));
        }
    }
 
    /*
     * If we found any conflicting parent default values, check to make sure
     * they were overridden by the child.
     */
    if (have_bogus_defaults)
    {
        foreach(lc, columns)
        {
            ColumnDef  *def = lfirst(lc);
 
            if (def->cooked_default == &bogus_marker)
            {
                if (def->generated)
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                             errmsg("column \"%s\" inherits conflicting generation expressions",
                                    def->colname),
                             errhint("To resolve the conflict, specify a generation expression explicitly.")));
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                             errmsg("column \"%s\" inherits conflicting default values",
                                    def->colname),
                             errhint("To resolve the conflict, specify a default explicitly.")));
            }
        }
    }
 
    *supconstr = constraints;
 
    return columns;
}
 
 
/*
 * MergeCheckConstraint
 *      Try to merge an inherited CHECK constraint with previous ones
 *
 * If we inherit identically-named constraints from multiple parents, we must
 * merge them, or throw an error if they don't have identical definitions.
 *
 * constraints is a list of CookedConstraint structs for previous constraints.
 *
 * If the new constraint matches an existing one, then the existing
 * constraint's inheritance count is updated.  If there is a conflict (same
 * name but different expression), throw an error.  If the constraint neither
 * matches nor conflicts with an existing one, a new constraint is appended to
 * the list.
 */
static List *
MergeCheckConstraint(List *constraints, const char *name, Node *expr)
{
    ListCell   *lc;
    CookedConstraint *newcon;
 
    foreach(lc, constraints)
    {
        CookedConstraint *ccon = (CookedConstraint *) lfirst(lc);
 
        Assert(ccon->contype == CONSTR_CHECK);
 
        /* Non-matching names never conflict */
        if (strcmp(ccon->name, name) != 0)
            continue;
 
        if (equal(expr, ccon->expr))
        {
            /* OK to merge constraint with existing */
            if (pg_add_s16_overflow(ccon->inhcount, 1,
                                    &ccon->inhcount))
                ereport(ERROR,
                        errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                        errmsg("too many inheritance parents"));
            return constraints;
        }
 
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_OBJECT),
                 errmsg("check constraint name \"%s\" appears multiple times but with different expressions",
                        name)));
    }
 
    /*
     * Constraint couldn't be merged with an existing one and also didn't
     * conflict with an existing one, so add it as a new one to the list.
     */
    newcon = palloc0_object(CookedConstraint);
    newcon->contype = CONSTR_CHECK;
    newcon->name = pstrdup(name);
    newcon->expr = expr;
    newcon->inhcount = 1;
    return lappend(constraints, newcon);
}
 
/*
 * MergeChildAttribute
 *      Merge given child attribute definition into given inherited attribute.
 *
 * Input arguments:
 * 'inh_columns' is the list of inherited ColumnDefs.
 * 'exist_attno' is the number of the inherited attribute in inh_columns
 * 'newcol_attno' is the attribute number in child table's schema definition
 * 'newdef' is the column/attribute definition from the child table.
 *
 * The ColumnDef in 'inh_columns' list is modified.  The child attribute's
 * ColumnDef remains unchanged.
 *
 * Notes:
 * - The attribute is merged according to the rules laid out in the prologue
 *   of MergeAttributes().
 * - If matching inherited attribute exists but the child attribute can not be
 *   merged into it, the function throws respective errors.
 * - A partition can not have its own column definitions. Hence this function
 *   is applicable only to a regular inheritance child.
 */
static void
MergeChildAttribute(List *inh_columns, int exist_attno, int newcol_attno, const ColumnDef *newdef)
{
    char       *attributeName = newdef->colname;
    ColumnDef  *inhdef;
    Oid         inhtypeid,
                newtypeid;
    int32       inhtypmod,
                newtypmod;
    Oid         inhcollid,
                newcollid;
 
    if (exist_attno == newcol_attno)
        ereport(NOTICE,
                (errmsg("merging column \"%s\" with inherited definition",
                        attributeName)));
    else
        ereport(NOTICE,
                (errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
                 errdetail("User-specified column moved to the position of the inherited column.")));
 
    inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
    /*
     * Must have the same type and typmod
     */
    typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
    typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
    if (inhtypeid != newtypeid || inhtypmod != newtypmod)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("column \"%s\" has a type conflict",
                        attributeName),
                 errdetail("%s versus %s",
                           format_type_with_typemod(inhtypeid, inhtypmod),
                           format_type_with_typemod(newtypeid, newtypmod))));
 
    /*
     * Must have the same collation
     */
    inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
    newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
    if (inhcollid != newcollid)
        ereport(ERROR,
                (errcode(ERRCODE_COLLATION_MISMATCH),
                 errmsg("column \"%s\" has a collation conflict",
                        attributeName),
                 errdetail("\"%s\" versus \"%s\"",
                           get_collation_name(inhcollid),
                           get_collation_name(newcollid))));
 
    /*
     * Identity is never inherited by a regular inheritance child. Pick
     * child's identity definition if there's one.
     */
    inhdef->identity = newdef->identity;
 
    /*
     * Copy storage parameter
     */
    if (inhdef->storage == 0)
        inhdef->storage = newdef->storage;
    else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("column \"%s\" has a storage parameter conflict",
                        attributeName),
                 errdetail("%s versus %s",
                           storage_name(inhdef->storage),
                           storage_name(newdef->storage))));
 
    /*
     * Copy compression parameter
     */
    if (inhdef->compression == NULL)
        inhdef->compression = newdef->compression;
    else if (newdef->compression != NULL)
    {
        if (strcmp(inhdef->compression, newdef->compression) != 0)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("column \"%s\" has a compression method conflict",
                            attributeName),
                     errdetail("%s versus %s", inhdef->compression, newdef->compression)));
    }
 
    /*
     * Merge of not-null constraints = OR 'em together
     */
    inhdef->is_not_null |= newdef->is_not_null;
 
    /*
     * Check for conflicts related to generated columns.
     *
     * If the parent column is generated, the child column will be made a
     * generated column if it isn't already.  If it is a generated column,
     * we'll take its generation expression in preference to the parent's.  We
     * must check that the child column doesn't specify a default value or
     * identity, which matches the rules for a single column in
     * parse_utilcmd.c.
     *
     * Conversely, if the parent column is not generated, the child column
     * can't be either.  (We used to allow that, but it results in being able
     * to override the generation expression via UPDATEs through the parent.)
     */
    if (inhdef->generated)
    {
        if (newdef->raw_default && !newdef->generated)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                     errmsg("column \"%s\" inherits from generated column but specifies default",
                            inhdef->colname)));
        if (newdef->identity)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                     errmsg("column \"%s\" inherits from generated column but specifies identity",
                            inhdef->colname)));
    }
    else
    {
        if (newdef->generated)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                     errmsg("child column \"%s\" specifies generation expression",
                            inhdef->colname),
                     errhint("A child table column cannot be generated unless its parent column is.")));
    }
 
    /*
     * If new def has a default, override previous default
     */
    if (newdef->raw_default != NULL)
    {
        inhdef->raw_default = newdef->raw_default;
        inhdef->cooked_default = newdef->cooked_default;
    }
 
    /* Mark the column as locally defined */
    inhdef->is_local = true;
}
 
/*
 * MergeInheritedAttribute
 *      Merge given parent attribute definition into specified attribute
 *      inherited from the previous parents.
 *
 * Input arguments:
 * 'inh_columns' is the list of previously inherited ColumnDefs.
 * 'exist_attno' is the number the existing matching attribute in inh_columns.
 * 'newdef' is the new parent column/attribute definition to be merged.
 *
 * The matching ColumnDef in 'inh_columns' list is modified and returned.
 *
 * Notes:
 * - The attribute is merged according to the rules laid out in the prologue
 *   of MergeAttributes().
 * - If matching inherited attribute exists but the new attribute can not be
 *   merged into it, the function throws respective errors.
 * - A partition inherits from only a single parent. Hence this function is
 *   applicable only to a regular inheritance.
 */
static ColumnDef *
MergeInheritedAttribute(List *inh_columns,
                        int exist_attno,
                        const ColumnDef *newdef)
{
    char       *attributeName = newdef->colname;
    ColumnDef  *prevdef;
    Oid         prevtypeid,
                newtypeid;
    int32       prevtypmod,
                newtypmod;
    Oid         prevcollid,
                newcollid;
 
    ereport(NOTICE,
            (errmsg("merging multiple inherited definitions of column \"%s\"",
                    attributeName)));
    prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
    /*
     * Must have the same type and typmod
     */
    typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
    typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
    if (prevtypeid != newtypeid || prevtypmod != newtypmod)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("inherited column \"%s\" has a type conflict",
                        attributeName),
                 errdetail("%s versus %s",
                           format_type_with_typemod(prevtypeid, prevtypmod),
                           format_type_with_typemod(newtypeid, newtypmod))));
 
    /*
     * Merge of not-null constraints = OR 'em together
     */
    prevdef->is_not_null |= newdef->is_not_null;
 
    /*
     * Must have the same collation
     */
    prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
    newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
    if (prevcollid != newcollid)
        ereport(ERROR,
                (errcode(ERRCODE_COLLATION_MISMATCH),
                 errmsg("inherited column \"%s\" has a collation conflict",
                        attributeName),
                 errdetail("\"%s\" versus \"%s\"",
                           get_collation_name(prevcollid),
                           get_collation_name(newcollid))));
 
    /*
     * Copy/check storage parameter
     */
    if (prevdef->storage == 0)
        prevdef->storage = newdef->storage;
    else if (prevdef->storage != newdef->storage)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("inherited column \"%s\" has a storage parameter conflict",
                        attributeName),
                 errdetail("%s versus %s",
                           storage_name(prevdef->storage),
                           storage_name(newdef->storage))));
 
    /*
     * Copy/check compression parameter
     */
    if (prevdef->compression == NULL)
        prevdef->compression = newdef->compression;
    else if (newdef->compression != NULL)
    {
        if (strcmp(prevdef->compression, newdef->compression) != 0)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("column \"%s\" has a compression method conflict",
                            attributeName),
                     errdetail("%s versus %s",
                               prevdef->compression, newdef->compression)));
    }
 
    /*
     * Check for GENERATED conflicts
     */
    if (prevdef->generated != newdef->generated)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("inherited column \"%s\" has a generation conflict",
                        attributeName)));
 
    /*
     * Default and other constraints are handled by the caller.
     */
 
    if (pg_add_s16_overflow(prevdef->inhcount, 1,
                            &prevdef->inhcount))
        ereport(ERROR,
                errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                errmsg("too many inheritance parents"));
 
    return prevdef;
}
 
/*
 * StoreCatalogInheritance
 *      Updates the system catalogs with proper inheritance information.
 *
 * supers is a list of the OIDs of the new relation's direct ancestors.
 */
static void
StoreCatalogInheritance(Oid relationId, List *supers,
                        bool child_is_partition)
{
    Relation    relation;
    int32       seqNumber;
    ListCell   *entry;
 
    /*
     * sanity checks
     */
    Assert(OidIsValid(relationId));
 
    if (supers == NIL)
        return;
 
    /*
     * Store INHERITS information in pg_inherits using direct ancestors only.
     * Also enter dependencies on the direct ancestors, and make sure they are
     * marked with relhassubclass = true.
     *
     * (Once upon a time, both direct and indirect ancestors were found here
     * and then entered into pg_ipl.  Since that catalog doesn't exist
     * anymore, there's no need to look for indirect ancestors.)
     */
    relation = table_open(InheritsRelationId, RowExclusiveLock);
 
    seqNumber = 1;
    foreach(entry, supers)
    {
        Oid         parentOid = lfirst_oid(entry);
 
        StoreCatalogInheritance1(relationId, parentOid, seqNumber, relation,
                                 child_is_partition);
        seqNumber++;
    }
 
    table_close(relation, RowExclusiveLock);
}
 
/*
 * Make catalog entries showing relationId as being an inheritance child
 * of parentOid.  inhRelation is the already-opened pg_inherits catalog.
 */
static void
StoreCatalogInheritance1(Oid relationId, Oid parentOid,
                         int32 seqNumber, Relation inhRelation,
                         bool child_is_partition)
{
    ObjectAddress childobject,
                parentobject;
 
    /* store the pg_inherits row */
    StoreSingleInheritance(relationId, parentOid, seqNumber);
 
    /*
     * Store a dependency too
     */
    parentobject.classId = RelationRelationId;
    parentobject.objectId = parentOid;
    parentobject.objectSubId = 0;
    childobject.classId = RelationRelationId;
    childobject.objectId = relationId;
    childobject.objectSubId = 0;
 
    recordDependencyOn(&childobject, &parentobject,
                       child_dependency_type(child_is_partition));
 
    /*
     * Post creation hook of this inheritance. Since object_access_hook
     * doesn't take multiple object identifiers, we relay oid of parent
     * relation using auxiliary_id argument.
     */
    InvokeObjectPostAlterHookArg(InheritsRelationId,
                                 relationId, 0,
                                 parentOid, false);
 
    /*
     * Mark the parent as having subclasses.
     */
    SetRelationHasSubclass(parentOid, true);
}
 
/*
 * Look for an existing column entry with the given name.
 *
 * Returns the index (starting with 1) if attribute already exists in columns,
 * 0 if it doesn't.
 */
static int
findAttrByName(const char *attributeName, const List *columns)
{
    ListCell   *lc;
    int         i = 1;
 
    foreach(lc, columns)
    {
        if (strcmp(attributeName, lfirst_node(ColumnDef, lc)->colname) == 0)
            return i;
 
        i++;
    }
    return 0;
}
 
 
/*
 * SetRelationHasSubclass
 *      Set the value of the relation's relhassubclass field in pg_class.
 *
 * It's always safe to set this field to true, because all SQL commands are
 * ready to see true and then find no children.  On the other hand, commands
 * generally assume zero children if this is false.
 *
 * Caller must hold any self-exclusive lock until end of transaction.  If the
 * new value is false, caller must have acquired that lock before reading the
 * evidence that justified the false value.  That way, it properly waits if
 * another backend is simultaneously concluding no need to change the tuple
 * (new and old values are true).
 *
 * NOTE: an important side-effect of this operation is that an SI invalidation
 * message is sent out to all backends --- including me --- causing plans
 * referencing the relation to be rebuilt with the new list of children.
 * This must happen even if we find that no change is needed in the pg_class
 * row.
 */
void
SetRelationHasSubclass(Oid relationId, bool relhassubclass)
{
    Relation    relationRelation;
    HeapTuple   tuple;
    Form_pg_class classtuple;
 
    Assert(CheckRelationOidLockedByMe(relationId,
                                      ShareUpdateExclusiveLock, false) ||
           CheckRelationOidLockedByMe(relationId,
                                      ShareRowExclusiveLock, true));
 
    /*
     * Fetch a modifiable copy of the tuple, modify it, update pg_class.
     */
    relationRelation = table_open(RelationRelationId, RowExclusiveLock);
    tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relationId));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", relationId);
    classtuple = (Form_pg_class) GETSTRUCT(tuple);
 
    if (classtuple->relhassubclass != relhassubclass)
    {
        classtuple->relhassubclass = relhassubclass;
        CatalogTupleUpdate(relationRelation, &tuple->t_self, tuple);
    }
    else
    {
        /* no need to change tuple, but force relcache rebuild anyway */
        CacheInvalidateRelcacheByTuple(tuple);
    }
 
    heap_freetuple(tuple);
    table_close(relationRelation, RowExclusiveLock);
}
 
/*
 * CheckRelationTableSpaceMove
 *      Check if relation can be moved to new tablespace.
 *
 * NOTE: The caller must hold AccessExclusiveLock on the relation.
 *
 * Returns true if the relation can be moved to the new tablespace; raises
 * an error if it is not possible to do the move; returns false if the move
 * would have no effect.
 */
bool
CheckRelationTableSpaceMove(Relation rel, Oid newTableSpaceId)
{
    Oid         oldTableSpaceId;
 
    /*
     * No work if no change in tablespace.  Note that MyDatabaseTableSpace is
     * stored as 0.
     */
    oldTableSpaceId = rel->rd_rel->reltablespace;
    if (newTableSpaceId == oldTableSpaceId ||
        (newTableSpaceId == MyDatabaseTableSpace && oldTableSpaceId == 0))
        return false;
 
    /*
     * We cannot support moving mapped relations into different tablespaces.
     * (In particular this eliminates all shared catalogs.)
     */
    if (RelationIsMapped(rel))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot move system relation \"%s\"",
                        RelationGetRelationName(rel))));
 
    /* Cannot move a non-shared relation into pg_global */
    if (newTableSpaceId == GLOBALTABLESPACE_OID)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("only shared relations can be placed in pg_global tablespace")));
 
    /*
     * Do not allow moving temp tables of other backends ... their local
     * buffer manager is not going to cope.
     */
    if (RELATION_IS_OTHER_TEMP(rel))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot move temporary tables of other sessions")));
 
    return true;
}
 
/*
 * SetRelationTableSpace
 *      Set new reltablespace and relfilenumber in pg_class entry.
 *
 * newTableSpaceId is the new tablespace for the relation, and
 * newRelFilenumber its new filenumber.  If newRelFilenumber is
 * InvalidRelFileNumber, this field is not updated.
 *
 * NOTE: The caller must hold AccessExclusiveLock on the relation.
 *
 * The caller of this routine had better check if a relation can be
 * moved to this new tablespace by calling CheckRelationTableSpaceMove()
 * first, and is responsible for making the change visible with
 * CommandCounterIncrement().
 */
void
SetRelationTableSpace(Relation rel,
                      Oid newTableSpaceId,
                      RelFileNumber newRelFilenumber)
{
    Relation    pg_class;
    HeapTuple   tuple;
    ItemPointerData otid;
    Form_pg_class rd_rel;
    Oid         reloid = RelationGetRelid(rel);
 
    Assert(CheckRelationTableSpaceMove(rel, newTableSpaceId));
 
    /* Get a modifiable copy of the relation's pg_class row. */
    pg_class = table_open(RelationRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheLockedCopy1(RELOID, ObjectIdGetDatum(reloid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", reloid);
    otid = tuple->t_self;
    rd_rel = (Form_pg_class) GETSTRUCT(tuple);
 
    /* Update the pg_class row. */
    rd_rel->reltablespace = (newTableSpaceId == MyDatabaseTableSpace) ?
        InvalidOid : newTableSpaceId;
    if (RelFileNumberIsValid(newRelFilenumber))
        rd_rel->relfilenode = newRelFilenumber;
    CatalogTupleUpdate(pg_class, &otid, tuple);
    UnlockTuple(pg_class, &otid, InplaceUpdateTupleLock);
 
    /*
     * Record dependency on tablespace.  This is only required for relations
     * that have no physical storage.
     */
    if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
        changeDependencyOnTablespace(RelationRelationId, reloid,
                                     rd_rel->reltablespace);
 
    heap_freetuple(tuple);
    table_close(pg_class, RowExclusiveLock);
}
 
/*
 *      renameatt_check         - basic sanity checks before attribute rename
 */
static void
renameatt_check(Oid myrelid, Form_pg_class classform, bool recursing)
{
    char        relkind = classform->relkind;
 
    if (classform->reloftype && !recursing)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot rename column of typed table")));
 
    /*
     * Renaming the columns of sequences or toast tables doesn't actually
     * break anything from the system's point of view, since internal
     * references are by attnum.  But it doesn't seem right to allow users to
     * change names that are hardcoded into the system, hence the following
     * restriction.
     */
    if (relkind != RELKIND_RELATION &&
        relkind != RELKIND_VIEW &&
        relkind != RELKIND_MATVIEW &&
        relkind != RELKIND_COMPOSITE_TYPE &&
        relkind != RELKIND_INDEX &&
        relkind != RELKIND_PARTITIONED_INDEX &&
        relkind != RELKIND_FOREIGN_TABLE &&
        relkind != RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot rename columns of relation \"%s\"",
                        NameStr(classform->relname)),
                 errdetail_relkind_not_supported(relkind)));
 
    /*
     * permissions checking.  only the owner of a class can change its schema.
     */
    if (!object_ownercheck(RelationRelationId, myrelid, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(myrelid)),
                       NameStr(classform->relname));
    if (!allowSystemTableMods && IsSystemClass(myrelid, classform))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: \"%s\" is a system catalog",
                        NameStr(classform->relname))));
}
 
/*
 *      renameatt_internal      - workhorse for renameatt
 *
 * Return value is the attribute number in the 'myrelid' relation.
 */
static AttrNumber
renameatt_internal(Oid myrelid,
                   const char *oldattname,
                   const char *newattname,
                   bool recurse,
                   bool recursing,
                   int expected_parents,
                   DropBehavior behavior)
{
    Relation    targetrelation;
    Relation    attrelation;
    HeapTuple   atttup;
    Form_pg_attribute attform;
    AttrNumber  attnum;
 
    /*
     * Grab an exclusive lock on the target table, which we will NOT release
     * until end of transaction.
     */
    targetrelation = relation_open(myrelid, AccessExclusiveLock);
    renameatt_check(myrelid, RelationGetForm(targetrelation), recursing);
 
    /*
     * if the 'recurse' flag is set then we are supposed to rename this
     * attribute in all classes that inherit from 'relname' (as well as in
     * 'relname').
     *
     * any permissions or problems with duplicate attributes will cause the
     * whole transaction to abort, which is what we want -- all or nothing.
     */
    if (recurse)
    {
        List       *child_oids,
                   *child_numparents;
        ListCell   *lo,
                   *li;
 
        /*
         * we need the number of parents for each child so that the recursive
         * calls to renameatt() can determine whether there are any parents
         * outside the inheritance hierarchy being processed.
         */
        child_oids = find_all_inheritors(myrelid, AccessExclusiveLock,
                                         &child_numparents);
 
        /*
         * find_all_inheritors does the recursive search of the inheritance
         * hierarchy, so all we have to do is process all of the relids in the
         * list that it returns.
         */
        forboth(lo, child_oids, li, child_numparents)
        {
            Oid         childrelid = lfirst_oid(lo);
            int         numparents = lfirst_int(li);
 
            if (childrelid == myrelid)
                continue;
            /* note we need not recurse again */
            renameatt_internal(childrelid, oldattname, newattname, false, true, numparents, behavior);
        }
    }
    else
    {
        /*
         * If we are told not to recurse, there had better not be any child
         * tables; else the rename would put them out of step.
         *
         * expected_parents will only be 0 if we are not already recursing.
         */
        if (expected_parents == 0 &&
            find_inheritance_children(myrelid, NoLock) != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("inherited column \"%s\" must be renamed in child tables too",
                            oldattname)));
    }
 
    /* rename attributes in typed tables of composite type */
    if (targetrelation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
    {
        List       *child_oids;
        ListCell   *lo;
 
        child_oids = find_typed_table_dependencies(targetrelation->rd_rel->reltype,
                                                   RelationGetRelationName(targetrelation),
                                                   behavior);
 
        foreach(lo, child_oids)
            renameatt_internal(lfirst_oid(lo), oldattname, newattname, true, true, 0, behavior);
    }
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
 
    atttup = SearchSysCacheCopyAttName(myrelid, oldattname);
    if (!HeapTupleIsValid(atttup))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" does not exist",
                        oldattname)));
    attform = (Form_pg_attribute) GETSTRUCT(atttup);
 
    attnum = attform->attnum;
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot rename system column \"%s\"",
                        oldattname)));
 
    /*
     * if the attribute is inherited, forbid the renaming.  if this is a
     * top-level call to renameatt(), then expected_parents will be 0, so the
     * effect of this code will be to prohibit the renaming if the attribute
     * is inherited at all.  if this is a recursive call to renameatt(),
     * expected_parents will be the number of parents the current relation has
     * within the inheritance hierarchy being processed, so we'll prohibit the
     * renaming only if there are additional parents from elsewhere.
     */
    if (attform->attinhcount > expected_parents)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot rename inherited column \"%s\"",
                        oldattname)));
 
    /* new name should not already exist */
    (void) check_for_column_name_collision(targetrelation, newattname, false);
 
    /* apply the update */
    namestrcpy(&(attform->attname), newattname);
 
    CatalogTupleUpdate(attrelation, &atttup->t_self, atttup);
 
    InvokeObjectPostAlterHook(RelationRelationId, myrelid, attnum);
 
    heap_freetuple(atttup);
 
    table_close(attrelation, RowExclusiveLock);
 
    relation_close(targetrelation, NoLock); /* close rel but keep lock */
 
    return attnum;
}
 
/*
 * Perform permissions and integrity checks before acquiring a relation lock.
 */
static void
RangeVarCallbackForRenameAttribute(const RangeVar *rv, Oid relid, Oid oldrelid,
                                   void *arg)
{
    HeapTuple   tuple;
    Form_pg_class form;
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tuple))
        return;                 /* concurrently dropped */
    form = (Form_pg_class) GETSTRUCT(tuple);
    renameatt_check(relid, form, false);
    ReleaseSysCache(tuple);
}
 
/*
 *      renameatt       - changes the name of an attribute in a relation
 *
 * The returned ObjectAddress is that of the renamed column.
 */
ObjectAddress
renameatt(RenameStmt *stmt)
{
    Oid         relid;
    AttrNumber  attnum;
    ObjectAddress address;
 
    /* lock level taken here should match renameatt_internal */
    relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
                                     stmt->missing_ok ? RVR_MISSING_OK : 0,
                                     RangeVarCallbackForRenameAttribute,
                                     NULL);
 
    if (!OidIsValid(relid))
    {
        ereport(NOTICE,
                (errmsg("relation \"%s\" does not exist, skipping",
                        stmt->relation->relname)));
        return InvalidObjectAddress;
    }
 
    attnum =
        renameatt_internal(relid,
                           stmt->subname,   /* old att name */
                           stmt->newname,   /* new att name */
                           stmt->relation->inh, /* recursive? */
                           false,   /* recursing? */
                           0,   /* expected inhcount */
                           stmt->behavior);
 
    ObjectAddressSubSet(address, RelationRelationId, relid, attnum);
 
    return address;
}
 
/*
 * same logic as renameatt_internal
 */
static ObjectAddress
rename_constraint_internal(Oid myrelid,
                           Oid mytypid,
                           const char *oldconname,
                           const char *newconname,
                           bool recurse,
                           bool recursing,
                           int expected_parents)
{
    Relation    targetrelation = NULL;
    Oid         constraintOid;
    HeapTuple   tuple;
    Form_pg_constraint con;
    ObjectAddress address;
 
    Assert(!myrelid || !mytypid);
 
    if (mytypid)
    {
        constraintOid = get_domain_constraint_oid(mytypid, oldconname, false);
    }
    else
    {
        targetrelation = relation_open(myrelid, AccessExclusiveLock);
 
        /*
         * don't tell it whether we're recursing; we allow changing typed
         * tables here
         */
        renameatt_check(myrelid, RelationGetForm(targetrelation), false);
 
        constraintOid = get_relation_constraint_oid(myrelid, oldconname, false);
    }
 
    tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for constraint %u",
             constraintOid);
    con = (Form_pg_constraint) GETSTRUCT(tuple);
 
    if (myrelid && con->contype == CONSTRAINT_CHECK && !con->connoinherit)
    {
        if (recurse)
        {
            List       *child_oids,
                       *child_numparents;
            ListCell   *lo,
                       *li;
 
            child_oids = find_all_inheritors(myrelid, AccessExclusiveLock,
                                             &child_numparents);
 
            forboth(lo, child_oids, li, child_numparents)
            {
                Oid         childrelid = lfirst_oid(lo);
                int         numparents = lfirst_int(li);
 
                if (childrelid == myrelid)
                    continue;
 
                rename_constraint_internal(childrelid, InvalidOid, oldconname, newconname, false, true, numparents);
            }
        }
        else
        {
            if (expected_parents == 0 &&
                find_inheritance_children(myrelid, NoLock) != NIL)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("inherited constraint \"%s\" must be renamed in child tables too",
                                oldconname)));
        }
 
        if (con->coninhcount > expected_parents)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("cannot rename inherited constraint \"%s\"",
                            oldconname)));
    }
 
    if (con->conindid
        && (con->contype == CONSTRAINT_PRIMARY
            || con->contype == CONSTRAINT_UNIQUE
            || con->contype == CONSTRAINT_EXCLUSION))
        /* rename the index; this renames the constraint as well */
        RenameRelationInternal(con->conindid, newconname, false, true);
    else
        RenameConstraintById(constraintOid, newconname);
 
    ObjectAddressSet(address, ConstraintRelationId, constraintOid);
 
    ReleaseSysCache(tuple);
 
    if (targetrelation)
    {
        /*
         * Invalidate relcache so as others can see the new constraint name.
         */
        CacheInvalidateRelcache(targetrelation);
 
        relation_close(targetrelation, NoLock); /* close rel but keep lock */
    }
 
    return address;
}
 
ObjectAddress
RenameConstraint(RenameStmt *stmt)
{
    Oid         relid = InvalidOid;
    Oid         typid = InvalidOid;
 
    if (stmt->renameType == OBJECT_DOMCONSTRAINT)
    {
        Relation    rel;
        HeapTuple   tup;
 
        typid = typenameTypeId(NULL, makeTypeNameFromNameList(castNode(List, stmt->object)));
        rel = table_open(TypeRelationId, RowExclusiveLock);
        tup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
        if (!HeapTupleIsValid(tup))
            elog(ERROR, "cache lookup failed for type %u", typid);
        checkDomainOwner(tup);
        ReleaseSysCache(tup);
        table_close(rel, NoLock);
    }
    else
    {
        /* lock level taken here should match rename_constraint_internal */
        relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
                                         stmt->missing_ok ? RVR_MISSING_OK : 0,
                                         RangeVarCallbackForRenameAttribute,
                                         NULL);
        if (!OidIsValid(relid))
        {
            ereport(NOTICE,
                    (errmsg("relation \"%s\" does not exist, skipping",
                            stmt->relation->relname)));
            return InvalidObjectAddress;
        }
    }
 
    return
        rename_constraint_internal(relid, typid,
                                   stmt->subname,
                                   stmt->newname,
                                   (stmt->relation &&
                                    stmt->relation->inh),   /* recursive? */
                                   false,   /* recursing? */
                                   0 /* expected inhcount */ );
}
 
/*
 * Execute ALTER TABLE/INDEX/SEQUENCE/VIEW/MATERIALIZED VIEW/FOREIGN TABLE
 * RENAME
 */
ObjectAddress
RenameRelation(RenameStmt *stmt)
{
    bool        is_index_stmt = stmt->renameType == OBJECT_INDEX;
    Oid         relid;
    ObjectAddress address;
 
    /*
     * Grab an exclusive lock on the target table, index, sequence, view,
     * materialized view, or foreign table, which we will NOT release until
     * end of transaction.
     *
     * Lock level used here should match RenameRelationInternal, to avoid lock
     * escalation.  However, because ALTER INDEX can be used with any relation
     * type, we mustn't believe without verification.
     */
    for (;;)
    {
        LOCKMODE    lockmode;
        char        relkind;
        bool        obj_is_index;
 
        lockmode = is_index_stmt ? ShareUpdateExclusiveLock : AccessExclusiveLock;
 
        relid = RangeVarGetRelidExtended(stmt->relation, lockmode,
                                         stmt->missing_ok ? RVR_MISSING_OK : 0,
                                         RangeVarCallbackForAlterRelation,
                                         (void *) stmt);
 
        if (!OidIsValid(relid))
        {
            ereport(NOTICE,
                    (errmsg("relation \"%s\" does not exist, skipping",
                            stmt->relation->relname)));
            return InvalidObjectAddress;
        }
 
        /*
         * We allow mismatched statement and object types (e.g., ALTER INDEX
         * to rename a table), but we might've used the wrong lock level.  If
         * that happens, retry with the correct lock level.  We don't bother
         * if we already acquired AccessExclusiveLock with an index, however.
         */
        relkind = get_rel_relkind(relid);
        obj_is_index = (relkind == RELKIND_INDEX ||
                        relkind == RELKIND_PARTITIONED_INDEX);
        if (obj_is_index || is_index_stmt == obj_is_index)
            break;
 
        UnlockRelationOid(relid, lockmode);
        is_index_stmt = obj_is_index;
    }
 
    /* Do the work */
    RenameRelationInternal(relid, stmt->newname, false, is_index_stmt);
 
    ObjectAddressSet(address, RelationRelationId, relid);
 
    return address;
}
 
/*
 *      RenameRelationInternal - change the name of a relation
 */
void
RenameRelationInternal(Oid myrelid, const char *newrelname, bool is_internal, bool is_index)
{
    Relation    targetrelation;
    Relation    relrelation;    /* for RELATION relation */
    ItemPointerData otid;
    HeapTuple   reltup;
    Form_pg_class relform;
    Oid         namespaceId;
 
    /*
     * Grab a lock on the target relation, which we will NOT release until end
     * of transaction.  We need at least a self-exclusive lock so that
     * concurrent DDL doesn't overwrite the rename if they start updating
     * while still seeing the old version.  The lock also guards against
     * triggering relcache reloads in concurrent sessions, which might not
     * handle this information changing under them.  For indexes, we can use a
     * reduced lock level because RelationReloadIndexInfo() handles indexes
     * specially.
     */
    targetrelation = relation_open(myrelid, is_index ? ShareUpdateExclusiveLock : AccessExclusiveLock);
    namespaceId = RelationGetNamespace(targetrelation);
 
    /*
     * Find relation's pg_class tuple, and make sure newrelname isn't in use.
     */
    relrelation = table_open(RelationRelationId, RowExclusiveLock);
 
    reltup = SearchSysCacheLockedCopy1(RELOID, ObjectIdGetDatum(myrelid));
    if (!HeapTupleIsValid(reltup))  /* shouldn't happen */
        elog(ERROR, "cache lookup failed for relation %u", myrelid);
    otid = reltup->t_self;
    relform = (Form_pg_class) GETSTRUCT(reltup);
 
    if (get_relname_relid(newrelname, namespaceId) != InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_TABLE),
                 errmsg("relation \"%s\" already exists",
                        newrelname)));
 
    /*
     * RenameRelation is careful not to believe the caller's idea of the
     * relation kind being handled.  We don't have to worry about this, but
     * let's not be totally oblivious to it.  We can process an index as
     * not-an-index, but not the other way around.
     */
    Assert(!is_index ||
           is_index == (targetrelation->rd_rel->relkind == RELKIND_INDEX ||
                        targetrelation->rd_rel->relkind == RELKIND_PARTITIONED_INDEX));
 
    /*
     * Update pg_class tuple with new relname.  (Scribbling on reltup is OK
     * because it's a copy...)
     */
    namestrcpy(&(relform->relname), newrelname);
 
    CatalogTupleUpdate(relrelation, &otid, reltup);
    UnlockTuple(relrelation, &otid, InplaceUpdateTupleLock);
 
    InvokeObjectPostAlterHookArg(RelationRelationId, myrelid, 0,
                                 InvalidOid, is_internal);
 
    heap_freetuple(reltup);
    table_close(relrelation, RowExclusiveLock);
 
    /*
     * Also rename the associated type, if any.
     */
    if (OidIsValid(targetrelation->rd_rel->reltype))
        RenameTypeInternal(targetrelation->rd_rel->reltype,
                           newrelname, namespaceId);
 
    /*
     * Also rename the associated constraint, if any.
     */
    if (targetrelation->rd_rel->relkind == RELKIND_INDEX ||
        targetrelation->rd_rel->relkind == RELKIND_PARTITIONED_INDEX)
    {
        Oid         constraintId = get_index_constraint(myrelid);
 
        if (OidIsValid(constraintId))
            RenameConstraintById(constraintId, newrelname);
    }
 
    /*
     * Close rel, but keep lock!
     */
    relation_close(targetrelation, NoLock);
}
 
/*
 *      ResetRelRewrite - reset relrewrite
 */
void
ResetRelRewrite(Oid myrelid)
{
    Relation    relrelation;    /* for RELATION relation */
    HeapTuple   reltup;
    Form_pg_class relform;
 
    /*
     * Find relation's pg_class tuple.
     */
    relrelation = table_open(RelationRelationId, RowExclusiveLock);
 
    reltup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(myrelid));
    if (!HeapTupleIsValid(reltup))  /* shouldn't happen */
        elog(ERROR, "cache lookup failed for relation %u", myrelid);
    relform = (Form_pg_class) GETSTRUCT(reltup);
 
    /*
     * Update pg_class tuple.
     */
    relform->relrewrite = InvalidOid;
 
    CatalogTupleUpdate(relrelation, &reltup->t_self, reltup);
 
    heap_freetuple(reltup);
    table_close(relrelation, RowExclusiveLock);
}
 
/*
 * Disallow ALTER TABLE (and similar commands) when the current backend has
 * any open reference to the target table besides the one just acquired by
 * the calling command; this implies there's an open cursor or active plan.
 * We need this check because our lock doesn't protect us against stomping
 * on our own foot, only other people's feet!
 *
 * For ALTER TABLE, the only case known to cause serious trouble is ALTER
 * COLUMN TYPE, and some changes are obviously pretty benign, so this could
 * possibly be relaxed to only error out for certain types of alterations.
 * But the use-case for allowing any of these things is not obvious, so we
 * won't work hard at it for now.
 *
 * We also reject these commands if there are any pending AFTER trigger events
 * for the rel.  This is certainly necessary for the rewriting variants of
 * ALTER TABLE, because they don't preserve tuple TIDs and so the pending
 * events would try to fetch the wrong tuples.  It might be overly cautious
 * in other cases, but again it seems better to err on the side of paranoia.
 *
 * REINDEX calls this with "rel" referencing the index to be rebuilt; here
 * we are worried about active indexscans on the index.  The trigger-event
 * check can be skipped, since we are doing no damage to the parent table.
 *
 * The statement name (eg, "ALTER TABLE") is passed for use in error messages.
 */
void
CheckTableNotInUse(Relation rel, const char *stmt)
{
    int         expected_refcnt;
 
    expected_refcnt = rel->rd_isnailed ? 2 : 1;
    if (rel->rd_refcnt != expected_refcnt)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_IN_USE),
        /* translator: first %s is a SQL command, eg ALTER TABLE */
                 errmsg("cannot %s \"%s\" because it is being used by active queries in this session",
                        stmt, RelationGetRelationName(rel))));
 
    if (rel->rd_rel->relkind != RELKIND_INDEX &&
        rel->rd_rel->relkind != RELKIND_PARTITIONED_INDEX &&
        AfterTriggerPendingOnRel(RelationGetRelid(rel)))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_IN_USE),
        /* translator: first %s is a SQL command, eg ALTER TABLE */
                 errmsg("cannot %s \"%s\" because it has pending trigger events",
                        stmt, RelationGetRelationName(rel))));
}
 
/*
 * CheckAlterTableIsSafe
 *      Verify that it's safe to allow ALTER TABLE on this relation.
 *
 * This consists of CheckTableNotInUse() plus a check that the relation
 * isn't another session's temp table.  We must split out the temp-table
 * check because there are callers of CheckTableNotInUse() that don't want
 * that, notably DROP TABLE.  (We must allow DROP or we couldn't clean out
 * an orphaned temp schema.)  Compare truncate_check_activity().
 */
static void
CheckAlterTableIsSafe(Relation rel)
{
    /*
     * Don't allow ALTER on temp tables of other backends.  Their local buffer
     * manager is not going to cope if we need to change the table's contents.
     * Even if we don't, there may be optimizations that assume temp tables
     * aren't subject to such interference.
     */
    if (RELATION_IS_OTHER_TEMP(rel))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter temporary tables of other sessions")));
 
    /*
     * Also check for active uses of the relation in the current transaction,
     * including open scans and pending AFTER trigger events.
     */
    CheckTableNotInUse(rel, "ALTER TABLE");
}
 
/*
 * AlterTableLookupRelation
 *      Look up, and lock, the OID for the relation named by an alter table
 *      statement.
 */
Oid
AlterTableLookupRelation(AlterTableStmt *stmt, LOCKMODE lockmode)
{
    return RangeVarGetRelidExtended(stmt->relation, lockmode,
                                    stmt->missing_ok ? RVR_MISSING_OK : 0,
                                    RangeVarCallbackForAlterRelation,
                                    (void *) stmt);
}
 
/*
 * AlterTable
 *      Execute ALTER TABLE, which can be a list of subcommands
 *
 * ALTER TABLE is performed in three phases:
 *      1. Examine subcommands and perform pre-transformation checking.
 *      2. Validate and transform subcommands, and update system catalogs.
 *      3. Scan table(s) to check new constraints, and optionally recopy
 *         the data into new table(s).
 * Phase 3 is not performed unless one or more of the subcommands requires
 * it.  The intention of this design is to allow multiple independent
 * updates of the table schema to be performed with only one pass over the
 * data.
 *
 * ATPrepCmd performs phase 1.  A "work queue" entry is created for
 * each table to be affected (there may be multiple affected tables if the
 * commands traverse a table inheritance hierarchy).  Also we do preliminary
 * validation of the subcommands.  Because earlier subcommands may change
 * the catalog state seen by later commands, there are limits to what can
 * be done in this phase.  Generally, this phase acquires table locks,
 * checks permissions and relkind, and recurses to find child tables.
 *
 * ATRewriteCatalogs performs phase 2 for each affected table.
 * Certain subcommands need to be performed before others to avoid
 * unnecessary conflicts; for example, DROP COLUMN should come before
 * ADD COLUMN.  Therefore phase 1 divides the subcommands into multiple
 * lists, one for each logical "pass" of phase 2.
 *
 * ATRewriteTables performs phase 3 for those tables that need it.
 *
 * For most subcommand types, phases 2 and 3 do no explicit recursion,
 * since phase 1 already does it.  However, for certain subcommand types
 * it is only possible to determine how to recurse at phase 2 time; for
 * those cases, phase 1 sets the cmd->recurse flag.
 *
 * Thanks to the magic of MVCC, an error anywhere along the way rolls back
 * the whole operation; we don't have to do anything special to clean up.
 *
 * The caller must lock the relation, with an appropriate lock level
 * for the subcommands requested, using AlterTableGetLockLevel(stmt->cmds)
 * or higher. We pass the lock level down
 * so that we can apply it recursively to inherited tables. Note that the
 * lock level we want as we recurse might well be higher than required for
 * that specific subcommand. So we pass down the overall lock requirement,
 * rather than reassess it at lower levels.
 *
 * The caller also provides a "context" which is to be passed back to
 * utility.c when we need to execute a subcommand such as CREATE INDEX.
 * Some of the fields therein, such as the relid, are used here as well.
 */
void
AlterTable(AlterTableStmt *stmt, LOCKMODE lockmode,
           AlterTableUtilityContext *context)
{
    Relation    rel;
 
    /* Caller is required to provide an adequate lock. */
    rel = relation_open(context->relid, NoLock);
 
    CheckAlterTableIsSafe(rel);
 
    ATController(stmt, rel, stmt->cmds, stmt->relation->inh, lockmode, context);
}
 
/*
 * AlterTableInternal
 *
 * ALTER TABLE with target specified by OID
 *
 * We do not reject if the relation is already open, because it's quite
 * likely that one or more layers of caller have it open.  That means it
 * is unsafe to use this entry point for alterations that could break
 * existing query plans.  On the assumption it's not used for such, we
 * don't have to reject pending AFTER triggers, either.
 *
 * Also, since we don't have an AlterTableUtilityContext, this cannot be
 * used for any subcommand types that require parse transformation or
 * could generate subcommands that have to be passed to ProcessUtility.
 */
void
AlterTableInternal(Oid relid, List *cmds, bool recurse)
{
    Relation    rel;
    LOCKMODE    lockmode = AlterTableGetLockLevel(cmds);
 
    rel = relation_open(relid, lockmode);
 
    EventTriggerAlterTableRelid(relid);
 
    ATController(NULL, rel, cmds, recurse, lockmode, NULL);
}
 
/*
 * AlterTableGetLockLevel
 *
 * Sets the overall lock level required for the supplied list of subcommands.
 * Policy for doing this set according to needs of AlterTable(), see
 * comments there for overall explanation.
 *
 * Function is called before and after parsing, so it must give same
 * answer each time it is called. Some subcommands are transformed
 * into other subcommand types, so the transform must never be made to a
 * lower lock level than previously assigned. All transforms are noted below.
 *
 * Since this is called before we lock the table we cannot use table metadata
 * to influence the type of lock we acquire.
 *
 * There should be no lockmodes hardcoded into the subcommand functions. All
 * lockmode decisions for ALTER TABLE are made here only. The one exception is
 * ALTER TABLE RENAME which is treated as a different statement type T_RenameStmt
 * and does not travel through this section of code and cannot be combined with
 * any of the subcommands given here.
 *
 * Note that Hot Standby only knows about AccessExclusiveLocks on the primary
 * so any changes that might affect SELECTs running on standbys need to use
 * AccessExclusiveLocks even if you think a lesser lock would do, unless you
 * have a solution for that also.
 *
 * Also note that pg_dump uses only an AccessShareLock, meaning that anything
 * that takes a lock less than AccessExclusiveLock can change object definitions
 * while pg_dump is running. Be careful to check that the appropriate data is
 * derived by pg_dump using an MVCC snapshot, rather than syscache lookups,
 * otherwise we might end up with an inconsistent dump that can't restore.
 */
LOCKMODE
AlterTableGetLockLevel(List *cmds)
{
    /*
     * This only works if we read catalog tables using MVCC snapshots.
     */
    ListCell   *lcmd;
    LOCKMODE    lockmode = ShareUpdateExclusiveLock;
 
    foreach(lcmd, cmds)
    {
        AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);
        LOCKMODE    cmd_lockmode = AccessExclusiveLock; /* default for compiler */
 
        switch (cmd->subtype)
        {
                /*
                 * These subcommands rewrite the heap, so require full locks.
                 */
            case AT_AddColumn:  /* may rewrite heap, in some cases and visible
                                 * to SELECT */
            case AT_SetAccessMethod:    /* must rewrite heap */
            case AT_SetTableSpace:  /* must rewrite heap */
            case AT_AlterColumnType:    /* must rewrite heap */
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * These subcommands may require addition of toast tables. If
                 * we add a toast table to a table currently being scanned, we
                 * might miss data added to the new toast table by concurrent
                 * insert transactions.
                 */
            case AT_SetStorage: /* may add toast tables, see
                                 * ATRewriteCatalogs() */
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * Removing constraints can affect SELECTs that have been
                 * optimized assuming the constraint holds true. See also
                 * CloneFkReferenced.
                 */
            case AT_DropConstraint: /* as DROP INDEX */
            case AT_DropNotNull:    /* may change some SQL plans */
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * Subcommands that may be visible to concurrent SELECTs
                 */
            case AT_DropColumn: /* change visible to SELECT */
            case AT_AddColumnToView:    /* CREATE VIEW */
            case AT_DropOids:   /* used to equiv to DropColumn */
            case AT_EnableAlwaysRule:   /* may change SELECT rules */
            case AT_EnableReplicaRule:  /* may change SELECT rules */
            case AT_EnableRule: /* may change SELECT rules */
            case AT_DisableRule:    /* may change SELECT rules */
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * Changing owner may remove implicit SELECT privileges
                 */
            case AT_ChangeOwner:    /* change visible to SELECT */
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * Changing foreign table options may affect optimization.
                 */
            case AT_GenericOptions:
            case AT_AlterColumnGenericOptions:
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * These subcommands affect write operations only.
                 */
            case AT_EnableTrig:
            case AT_EnableAlwaysTrig:
            case AT_EnableReplicaTrig:
            case AT_EnableTrigAll:
            case AT_EnableTrigUser:
            case AT_DisableTrig:
            case AT_DisableTrigAll:
            case AT_DisableTrigUser:
                cmd_lockmode = ShareRowExclusiveLock;
                break;
 
                /*
                 * These subcommands affect write operations only. XXX
                 * Theoretically, these could be ShareRowExclusiveLock.
                 */
            case AT_ColumnDefault:
            case AT_CookedColumnDefault:
            case AT_AlterConstraint:
            case AT_AddIndex:   /* from ADD CONSTRAINT */
            case AT_AddIndexConstraint:
            case AT_ReplicaIdentity:
            case AT_SetNotNull:
            case AT_EnableRowSecurity:
            case AT_DisableRowSecurity:
            case AT_ForceRowSecurity:
            case AT_NoForceRowSecurity:
            case AT_AddIdentity:
            case AT_DropIdentity:
            case AT_SetIdentity:
            case AT_SetExpression:
            case AT_DropExpression:
            case AT_SetCompression:
                cmd_lockmode = AccessExclusiveLock;
                break;
 
            case AT_AddConstraint:
            case AT_ReAddConstraint:    /* becomes AT_AddConstraint */
            case AT_ReAddDomainConstraint:  /* becomes AT_AddConstraint */
                if (IsA(cmd->def, Constraint))
                {
                    Constraint *con = (Constraint *) cmd->def;
 
                    switch (con->contype)
                    {
                        case CONSTR_EXCLUSION:
                        case CONSTR_PRIMARY:
                        case CONSTR_UNIQUE:
 
                            /*
                             * Cases essentially the same as CREATE INDEX. We
                             * could reduce the lock strength to ShareLock if
                             * we can work out how to allow concurrent catalog
                             * updates. XXX Might be set down to
                             * ShareRowExclusiveLock but requires further
                             * analysis.
                             */
                            cmd_lockmode = AccessExclusiveLock;
                            break;
                        case CONSTR_FOREIGN:
 
                            /*
                             * We add triggers to both tables when we add a
                             * Foreign Key, so the lock level must be at least
                             * as strong as CREATE TRIGGER.
                             */
                            cmd_lockmode = ShareRowExclusiveLock;
                            break;
 
                        default:
                            cmd_lockmode = AccessExclusiveLock;
                    }
                }
                break;
 
                /*
                 * These subcommands affect inheritance behaviour. Queries
                 * started before us will continue to see the old inheritance
                 * behaviour, while queries started after we commit will see
                 * new behaviour. No need to prevent reads or writes to the
                 * subtable while we hook it up though. Changing the TupDesc
                 * may be a problem, so keep highest lock.
                 */
            case AT_AddInherit:
            case AT_DropInherit:
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * These subcommands affect implicit row type conversion. They
                 * have affects similar to CREATE/DROP CAST on queries. don't
                 * provide for invalidating parse trees as a result of such
                 * changes, so we keep these at AccessExclusiveLock.
                 */
            case AT_AddOf:
            case AT_DropOf:
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * Only used by CREATE OR REPLACE VIEW which must conflict
                 * with an SELECTs currently using the view.
                 */
            case AT_ReplaceRelOptions:
                cmd_lockmode = AccessExclusiveLock;
                break;
 
                /*
                 * These subcommands affect general strategies for performance
                 * and maintenance, though don't change the semantic results
                 * from normal data reads and writes. Delaying an ALTER TABLE
                 * behind currently active writes only delays the point where
                 * the new strategy begins to take effect, so there is no
                 * benefit in waiting. In this case the minimum restriction
                 * applies: we don't currently allow concurrent catalog
                 * updates.
                 */
            case AT_SetStatistics:  /* Uses MVCC in getTableAttrs() */
            case AT_ClusterOn:  /* Uses MVCC in getIndexes() */
            case AT_DropCluster:    /* Uses MVCC in getIndexes() */
            case AT_SetOptions: /* Uses MVCC in getTableAttrs() */
            case AT_ResetOptions:   /* Uses MVCC in getTableAttrs() */
                cmd_lockmode = ShareUpdateExclusiveLock;
                break;
 
            case AT_SetLogged:
            case AT_SetUnLogged:
                cmd_lockmode = AccessExclusiveLock;
                break;
 
            case AT_ValidateConstraint: /* Uses MVCC in getConstraints() */
                cmd_lockmode = ShareUpdateExclusiveLock;
                break;
 
                /*
                 * Rel options are more complex than first appears. Options
                 * are set here for tables, views and indexes; for historical
                 * reasons these can all be used with ALTER TABLE, so we can't
                 * decide between them using the basic grammar.
                 */
            case AT_SetRelOptions:  /* Uses MVCC in getIndexes() and
                                     * getTables() */
            case AT_ResetRelOptions:    /* Uses MVCC in getIndexes() and
                                         * getTables() */
                cmd_lockmode = AlterTableGetRelOptionsLockLevel((List *) cmd->def);
                break;
 
            case AT_AttachPartition:
                cmd_lockmode = ShareUpdateExclusiveLock;
                break;
 
            case AT_DetachPartition:
                if (((PartitionCmd *) cmd->def)->concurrent)
                    cmd_lockmode = ShareUpdateExclusiveLock;
                else
                    cmd_lockmode = AccessExclusiveLock;
                break;
 
            case AT_DetachPartitionFinalize:
                cmd_lockmode = ShareUpdateExclusiveLock;
                break;
 
            case AT_CheckNotNull:
 
                /*
                 * This only examines the table's schema; but lock must be
                 * strong enough to prevent concurrent DROP NOT NULL.
                 */
                cmd_lockmode = AccessShareLock;
                break;
 
            default:            /* oops */
                elog(ERROR, "unrecognized alter table type: %d",
                     (int) cmd->subtype);
                break;
        }
 
        /*
         * Take the greatest lockmode from any subcommand
         */
        if (cmd_lockmode > lockmode)
            lockmode = cmd_lockmode;
    }
 
    return lockmode;
}
 
/*
 * ATController provides top level control over the phases.
 *
 * parsetree is passed in to allow it to be passed to event triggers
 * when requested.
 */
static void
ATController(AlterTableStmt *parsetree,
             Relation rel, List *cmds, bool recurse, LOCKMODE lockmode,
             AlterTableUtilityContext *context)
{
    List       *wqueue = NIL;
    ListCell   *lcmd;
 
    /* Phase 1: preliminary examination of commands, create work queue */
    foreach(lcmd, cmds)
    {
        AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);
 
        ATPrepCmd(&wqueue, rel, cmd, recurse, false, lockmode, context);
    }
 
    /* Close the relation, but keep lock until commit */
    relation_close(rel, NoLock);
 
    /* Phase 2: update system catalogs */
    ATRewriteCatalogs(&wqueue, lockmode, context);
 
    /* Phase 3: scan/rewrite tables as needed, and run afterStmts */
    ATRewriteTables(parsetree, &wqueue, lockmode, context);
}
 
/*
 * ATPrepCmd
 *
 * Traffic cop for ALTER TABLE Phase 1 operations, including simple
 * recursion and permission checks.
 *
 * Caller must have acquired appropriate lock type on relation already.
 * This lock should be held until commit.
 */
static void
ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
          bool recurse, bool recursing, LOCKMODE lockmode,
          AlterTableUtilityContext *context)
{
    AlteredTableInfo *tab;
    AlterTablePass pass = AT_PASS_UNSET;
 
    /* Find or create work queue entry for this table */
    tab = ATGetQueueEntry(wqueue, rel);
 
    /*
     * Disallow any ALTER TABLE other than ALTER TABLE DETACH FINALIZE on
     * partitions that are pending detach.
     */
    if (rel->rd_rel->relispartition &&
        cmd->subtype != AT_DetachPartitionFinalize &&
        PartitionHasPendingDetach(RelationGetRelid(rel)))
        ereport(ERROR,
                errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                errmsg("cannot alter partition \"%s\" with an incomplete detach",
                       RelationGetRelationName(rel)),
                errhint("Use ALTER TABLE ... DETACH PARTITION ... FINALIZE to complete the pending detach operation."));
 
    /*
     * Copy the original subcommand for each table, so we can scribble on it.
     * This avoids conflicts when different child tables need to make
     * different parse transformations (for example, the same column may have
     * different column numbers in different children).
     */
    cmd = copyObject(cmd);
 
    /*
     * Do permissions and relkind checking, recursion to child tables if
     * needed, and any additional phase-1 processing needed.  (But beware of
     * adding any processing that looks at table details that another
     * subcommand could change.  In some cases we reject multiple subcommands
     * that could try to change the same state in contrary ways.)
     */
    switch (cmd->subtype)
    {
        case AT_AddColumn:      /* ADD COLUMN */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE |
                                ATT_COMPOSITE_TYPE | ATT_FOREIGN_TABLE);
            ATPrepAddColumn(wqueue, rel, recurse, recursing, false, cmd,
                            lockmode, context);
            /* Recursion occurs during execution phase */
            pass = AT_PASS_ADD_COL;
            break;
        case AT_AddColumnToView:    /* add column via CREATE OR REPLACE VIEW */
            ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
            ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
                            lockmode, context);
            /* Recursion occurs during execution phase */
            pass = AT_PASS_ADD_COL;
            break;
        case AT_ColumnDefault:  /* ALTER COLUMN DEFAULT */
 
            /*
             * We allow defaults on views so that INSERT into a view can have
             * default-ish behavior.  This works because the rewriter
             * substitutes default values into INSERTs before it expands
             * rules.
             */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_VIEW |
                                ATT_FOREIGN_TABLE);
            ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
            /* No command-specific prep needed */
            pass = cmd->def ? AT_PASS_ADD_OTHERCONSTR : AT_PASS_DROP;
            break;
        case AT_CookedColumnDefault:    /* add a pre-cooked default */
            /* This is currently used only in CREATE TABLE */
            /* (so the permission check really isn't necessary) */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            /* This command never recurses */
            pass = AT_PASS_ADD_OTHERCONSTR;
            break;
        case AT_AddIdentity:
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_VIEW |
                                ATT_FOREIGN_TABLE);
            /* Set up recursion for phase 2; no other prep needed */
            if (recurse)
                cmd->recurse = true;
            pass = AT_PASS_ADD_OTHERCONSTR;
            break;
        case AT_SetIdentity:
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_VIEW |
                                ATT_FOREIGN_TABLE);
            /* Set up recursion for phase 2; no other prep needed */
            if (recurse)
                cmd->recurse = true;
            /* This should run after AddIdentity, so do it in MISC pass */
            pass = AT_PASS_MISC;
            break;
        case AT_DropIdentity:
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_VIEW |
                                ATT_FOREIGN_TABLE);
            /* Set up recursion for phase 2; no other prep needed */
            if (recurse)
                cmd->recurse = true;
            pass = AT_PASS_DROP;
            break;
        case AT_DropNotNull:    /* ALTER COLUMN DROP NOT NULL */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
            pass = AT_PASS_DROP;
            break;
        case AT_SetNotNull:     /* ALTER COLUMN SET NOT NULL */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            /* Need command-specific recursion decision */
            ATPrepSetNotNull(wqueue, rel, cmd, recurse, recursing,
                             lockmode, context);
            pass = AT_PASS_COL_ATTRS;
            break;
        case AT_CheckNotNull:   /* check column is already marked NOT NULL */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
            /* No command-specific prep needed */
            pass = AT_PASS_COL_ATTRS;
            break;
        case AT_SetExpression:  /* ALTER COLUMN SET EXPRESSION */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
            pass = AT_PASS_SET_EXPRESSION;
            break;
        case AT_DropExpression: /* ALTER COLUMN DROP EXPRESSION */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
            ATPrepDropExpression(rel, cmd, recurse, recursing, lockmode);
            pass = AT_PASS_DROP;
            break;
        case AT_SetStatistics:  /* ALTER COLUMN SET STATISTICS */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_MATVIEW |
                                ATT_INDEX | ATT_PARTITIONED_INDEX | ATT_FOREIGN_TABLE);
            ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_SetOptions:     /* ALTER COLUMN SET ( options ) */
        case AT_ResetOptions:   /* ALTER COLUMN RESET ( options ) */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE |
                                ATT_MATVIEW | ATT_FOREIGN_TABLE);
            /* This command never recurses */
            pass = AT_PASS_MISC;
            break;
        case AT_SetStorage:     /* ALTER COLUMN SET STORAGE */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE |
                                ATT_MATVIEW | ATT_FOREIGN_TABLE);
            ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_SetCompression: /* ALTER COLUMN SET COMPRESSION */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_MATVIEW);
            /* This command never recurses */
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_DropColumn:     /* DROP COLUMN */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE |
                                ATT_COMPOSITE_TYPE | ATT_FOREIGN_TABLE);
            ATPrepDropColumn(wqueue, rel, recurse, recursing, cmd,
                             lockmode, context);
            /* Recursion occurs during execution phase */
            pass = AT_PASS_DROP;
            break;
        case AT_AddIndex:       /* ADD INDEX */
            ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_PARTITIONED_TABLE);
            /* This command never recurses */
            /* No command-specific prep needed */
            pass = AT_PASS_ADD_INDEX;
            break;
        case AT_AddConstraint:  /* ADD CONSTRAINT */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            /* Recursion occurs during execution phase */
            /* No command-specific prep needed except saving recurse flag */
            if (recurse)
                cmd->recurse = true;
            pass = AT_PASS_ADD_CONSTR;
            break;
        case AT_AddIndexConstraint: /* ADD CONSTRAINT USING INDEX */
            ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_PARTITIONED_TABLE);
            /* This command never recurses */
            /* No command-specific prep needed */
            pass = AT_PASS_ADD_INDEXCONSTR;
            break;
        case AT_DropConstraint: /* DROP CONSTRAINT */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            ATCheckPartitionsNotInUse(rel, lockmode);
            /* Other recursion occurs during execution phase */
            /* No command-specific prep needed except saving recurse flag */
            if (recurse)
                cmd->recurse = true;
            pass = AT_PASS_DROP;
            break;
        case AT_AlterColumnType:    /* ALTER COLUMN TYPE */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE |
                                ATT_COMPOSITE_TYPE | ATT_FOREIGN_TABLE);
            /* See comments for ATPrepAlterColumnType */
            cmd = ATParseTransformCmd(wqueue, tab, rel, cmd, recurse, lockmode,
                                      AT_PASS_UNSET, context);
            Assert(cmd != NULL);
            /* Performs own recursion */
            ATPrepAlterColumnType(wqueue, tab, rel, recurse, recursing, cmd,
                                  lockmode, context);
            pass = AT_PASS_ALTER_TYPE;
            break;
        case AT_AlterColumnGenericOptions:
            ATSimplePermissions(cmd->subtype, rel, ATT_FOREIGN_TABLE);
            /* This command never recurses */
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_ChangeOwner:    /* ALTER OWNER */
            /* This command never recurses */
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_ClusterOn:      /* CLUSTER ON */
        case AT_DropCluster:    /* SET WITHOUT CLUSTER */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_MATVIEW);
            /* These commands never recurse */
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_SetLogged:      /* SET LOGGED */
        case AT_SetUnLogged:    /* SET UNLOGGED */
            ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_SEQUENCE);
            if (tab->chgPersistence)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot change persistence setting twice")));
            ATPrepChangePersistence(tab, rel, cmd->subtype == AT_SetLogged);
            pass = AT_PASS_MISC;
            break;
        case AT_DropOids:       /* SET WITHOUT OIDS */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            pass = AT_PASS_DROP;
            break;
        case AT_SetAccessMethod:    /* SET ACCESS METHOD */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_MATVIEW);
 
            /* check if another access method change was already requested */
            if (tab->chgAccessMethod)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot have multiple SET ACCESS METHOD subcommands")));
 
            ATPrepSetAccessMethod(tab, rel, cmd->name);
            pass = AT_PASS_MISC;    /* does not matter; no work in Phase 2 */
            break;
        case AT_SetTableSpace:  /* SET TABLESPACE */
            ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_PARTITIONED_TABLE |
                                ATT_MATVIEW | ATT_INDEX | ATT_PARTITIONED_INDEX);
            /* This command never recurses */
            ATPrepSetTableSpace(tab, rel, cmd->name, lockmode);
            pass = AT_PASS_MISC;    /* doesn't actually matter */
            break;
        case AT_SetRelOptions:  /* SET (...) */
        case AT_ResetRelOptions:    /* RESET (...) */
        case AT_ReplaceRelOptions:  /* reset them all, then set just these */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_VIEW |
                                ATT_MATVIEW | ATT_INDEX);
            /* This command never recurses */
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_AddInherit:     /* INHERIT */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            /* This command never recurses */
            ATPrepAddInherit(rel);
            pass = AT_PASS_MISC;
            break;
        case AT_DropInherit:    /* NO INHERIT */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            /* This command never recurses */
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_AlterConstraint:    /* ALTER CONSTRAINT */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE);
            /* Recursion occurs during execution phase */
            pass = AT_PASS_MISC;
            break;
        case AT_ValidateConstraint: /* VALIDATE CONSTRAINT */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            /* Recursion occurs during execution phase */
            /* No command-specific prep needed except saving recurse flag */
            if (recurse)
                cmd->recurse = true;
            pass = AT_PASS_MISC;
            break;
        case AT_ReplicaIdentity:    /* REPLICA IDENTITY ... */
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_MATVIEW);
            pass = AT_PASS_MISC;
            /* This command never recurses */
            /* No command-specific prep needed */
            break;
        case AT_EnableTrig:     /* ENABLE TRIGGER variants */
        case AT_EnableAlwaysTrig:
        case AT_EnableReplicaTrig:
        case AT_EnableTrigAll:
        case AT_EnableTrigUser:
        case AT_DisableTrig:    /* DISABLE TRIGGER variants */
        case AT_DisableTrigAll:
        case AT_DisableTrigUser:
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
            /* Set up recursion for phase 2; no other prep needed */
            if (recurse)
                cmd->recurse = true;
            pass = AT_PASS_MISC;
            break;
        case AT_EnableRule:     /* ENABLE/DISABLE RULE variants */
        case AT_EnableAlwaysRule:
        case AT_EnableReplicaRule:
        case AT_DisableRule:
        case AT_AddOf:          /* OF */
        case AT_DropOf:         /* NOT OF */
        case AT_EnableRowSecurity:
        case AT_DisableRowSecurity:
        case AT_ForceRowSecurity:
        case AT_NoForceRowSecurity:
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_TABLE | ATT_PARTITIONED_TABLE);
            /* These commands never recurse */
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_GenericOptions:
            ATSimplePermissions(cmd->subtype, rel, ATT_FOREIGN_TABLE);
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_AttachPartition:
            ATSimplePermissions(cmd->subtype, rel,
                                ATT_PARTITIONED_TABLE | ATT_PARTITIONED_INDEX);
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_DetachPartition:
            ATSimplePermissions(cmd->subtype, rel, ATT_PARTITIONED_TABLE);
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        case AT_DetachPartitionFinalize:
            ATSimplePermissions(cmd->subtype, rel, ATT_PARTITIONED_TABLE);
            /* No command-specific prep needed */
            pass = AT_PASS_MISC;
            break;
        default:                /* oops */
            elog(ERROR, "unrecognized alter table type: %d",
                 (int) cmd->subtype);
            pass = AT_PASS_UNSET;   /* keep compiler quiet */
            break;
    }
    Assert(pass > AT_PASS_UNSET);
 
    /* Add the subcommand to the appropriate list for phase 2 */
    tab->subcmds[pass] = lappend(tab->subcmds[pass], cmd);
}
 
/*
 * ATRewriteCatalogs
 *
 * Traffic cop for ALTER TABLE Phase 2 operations.  Subcommands are
 * dispatched in a "safe" execution order (designed to avoid unnecessary
 * conflicts).
 */
static void
ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
                  AlterTableUtilityContext *context)
{
    ListCell   *ltab;
 
    /*
     * We process all the tables "in parallel", one pass at a time.  This is
     * needed because we may have to propagate work from one table to another
     * (specifically, ALTER TYPE on a foreign key's PK has to dispatch the
     * re-adding of the foreign key constraint to the other table).  Work can
     * only be propagated into later passes, however.
     */
    for (AlterTablePass pass = 0; pass < AT_NUM_PASSES; pass++)
    {
        /* Go through each table that needs to be processed */
        foreach(ltab, *wqueue)
        {
            AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
            List       *subcmds = tab->subcmds[pass];
            ListCell   *lcmd;
 
            if (subcmds == NIL)
                continue;
 
            /*
             * Open the relation and store it in tab.  This allows subroutines
             * close and reopen, if necessary.  Appropriate lock was obtained
             * by phase 1, needn't get it again.
             */
            tab->rel = relation_open(tab->relid, NoLock);
 
            foreach(lcmd, subcmds)
                ATExecCmd(wqueue, tab,
                          lfirst_node(AlterTableCmd, lcmd),
                          lockmode, pass, context);
 
            /*
             * After the ALTER TYPE or SET EXPRESSION pass, do cleanup work
             * (this is not done in ATExecAlterColumnType since it should be
             * done only once if multiple columns of a table are altered).
             */
            if (pass == AT_PASS_ALTER_TYPE || pass == AT_PASS_SET_EXPRESSION)
                ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
            if (tab->rel)
            {
                relation_close(tab->rel, NoLock);
                tab->rel = NULL;
            }
        }
    }
 
    /* Check to see if a toast table must be added. */
    foreach(ltab, *wqueue)
    {
        AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 
        /*
         * If the table is source table of ATTACH PARTITION command, we did
         * not modify anything about it that will change its toasting
         * requirement, so no need to check.
         */
        if (((tab->relkind == RELKIND_RELATION ||
              tab->relkind == RELKIND_PARTITIONED_TABLE) &&
             tab->partition_constraint == NULL) ||
            tab->relkind == RELKIND_MATVIEW)
            AlterTableCreateToastTable(tab->relid, (Datum) 0, lockmode);
    }
}
 
/*
 * ATExecCmd: dispatch a subcommand to appropriate execution routine
 */
static void
ATExecCmd(List **wqueue, AlteredTableInfo *tab,
          AlterTableCmd *cmd, LOCKMODE lockmode, AlterTablePass cur_pass,
          AlterTableUtilityContext *context)
{
    ObjectAddress address = InvalidObjectAddress;
    Relation    rel = tab->rel;
 
    switch (cmd->subtype)
    {
        case AT_AddColumn:      /* ADD COLUMN */
        case AT_AddColumnToView:    /* add column via CREATE OR REPLACE VIEW */
            address = ATExecAddColumn(wqueue, tab, rel, &cmd,
                                      cmd->recurse, false,
                                      lockmode, cur_pass, context);
            break;
        case AT_ColumnDefault:  /* ALTER COLUMN DEFAULT */
            address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
            break;
        case AT_CookedColumnDefault:    /* add a pre-cooked default */
            address = ATExecCookedColumnDefault(rel, cmd->num, cmd->def);
            break;
        case AT_AddIdentity:
            cmd = ATParseTransformCmd(wqueue, tab, rel, cmd, false, lockmode,
                                      cur_pass, context);
            Assert(cmd != NULL);
            address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode, cmd->recurse, false);
            break;
        case AT_SetIdentity:
            cmd = ATParseTransformCmd(wqueue, tab, rel, cmd, false, lockmode,
                                      cur_pass, context);
            Assert(cmd != NULL);
            address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode, cmd->recurse, false);
            break;
        case AT_DropIdentity:
            address = ATExecDropIdentity(rel, cmd->name, cmd->missing_ok, lockmode, cmd->recurse, false);
            break;
        case AT_DropNotNull:    /* ALTER COLUMN DROP NOT NULL */
            address = ATExecDropNotNull(rel, cmd->name, lockmode);
            break;
        case AT_SetNotNull:     /* ALTER COLUMN SET NOT NULL */
            address = ATExecSetNotNull(tab, rel, cmd->name, lockmode);
            break;
        case AT_CheckNotNull:   /* check column is already marked NOT NULL */
            ATExecCheckNotNull(tab, rel, cmd->name, lockmode);
            break;
        case AT_SetExpression:
            address = ATExecSetExpression(tab, rel, cmd->name, cmd->def, lockmode);
            break;
        case AT_DropExpression:
            address = ATExecDropExpression(rel, cmd->name, cmd->missing_ok, lockmode);
            break;
        case AT_SetStatistics:  /* ALTER COLUMN SET STATISTICS */
            address = ATExecSetStatistics(rel, cmd->name, cmd->num, cmd->def, lockmode);
            break;
        case AT_SetOptions:     /* ALTER COLUMN SET ( options ) */
            address = ATExecSetOptions(rel, cmd->name, cmd->def, false, lockmode);
            break;
        case AT_ResetOptions:   /* ALTER COLUMN RESET ( options ) */
            address = ATExecSetOptions(rel, cmd->name, cmd->def, true, lockmode);
            break;
        case AT_SetStorage:     /* ALTER COLUMN SET STORAGE */
            address = ATExecSetStorage(rel, cmd->name, cmd->def, lockmode);
            break;
        case AT_SetCompression: /* ALTER COLUMN SET COMPRESSION */
            address = ATExecSetCompression(rel, cmd->name, cmd->def,
                                           lockmode);
            break;
        case AT_DropColumn:     /* DROP COLUMN */
            address = ATExecDropColumn(wqueue, rel, cmd->name,
                                       cmd->behavior, cmd->recurse, false,
                                       cmd->missing_ok, lockmode,
                                       NULL);
            break;
        case AT_AddIndex:       /* ADD INDEX */
            address = ATExecAddIndex(tab, rel, (IndexStmt *) cmd->def, false,
                                     lockmode);
            break;
        case AT_ReAddIndex:     /* ADD INDEX */
            address = ATExecAddIndex(tab, rel, (IndexStmt *) cmd->def, true,
                                     lockmode);
            break;
        case AT_ReAddStatistics:    /* ADD STATISTICS */
            address = ATExecAddStatistics(tab, rel, (CreateStatsStmt *) cmd->def,
                                          true, lockmode);
            break;
        case AT_AddConstraint:  /* ADD CONSTRAINT */
            /* Transform the command only during initial examination */
            if (cur_pass == AT_PASS_ADD_CONSTR)
                cmd = ATParseTransformCmd(wqueue, tab, rel, cmd,
                                          cmd->recurse, lockmode,
                                          cur_pass, context);
            /* Depending on constraint type, might be no more work to do now */
            if (cmd != NULL)
                address =
                    ATExecAddConstraint(wqueue, tab, rel,
                                        (Constraint *) cmd->def,
                                        cmd->recurse, false, lockmode);
            break;
        case AT_ReAddConstraint:    /* Re-add pre-existing check constraint */
            address =
                ATExecAddConstraint(wqueue, tab, rel, (Constraint *) cmd->def,
                                    true, true, lockmode);
            break;
        case AT_ReAddDomainConstraint:  /* Re-add pre-existing domain check
                                         * constraint */
            address =
                AlterDomainAddConstraint(((AlterDomainStmt *) cmd->def)->typeName,
                                         ((AlterDomainStmt *) cmd->def)->def,
                                         NULL);
            break;
        case AT_ReAddComment:   /* Re-add existing comment */
            address = CommentObject((CommentStmt *) cmd->def);
            break;
        case AT_AddIndexConstraint: /* ADD CONSTRAINT USING INDEX */
            address = ATExecAddIndexConstraint(tab, rel, (IndexStmt *) cmd->def,
                                               lockmode);
            break;
        case AT_AlterConstraint:    /* ALTER CONSTRAINT */
            address = ATExecAlterConstraint(rel, cmd, false, false, lockmode);
            break;
        case AT_ValidateConstraint: /* VALIDATE CONSTRAINT */
            address = ATExecValidateConstraint(wqueue, rel, cmd->name, cmd->recurse,
                                               false, lockmode);
            break;
        case AT_DropConstraint: /* DROP CONSTRAINT */
            ATExecDropConstraint(rel, cmd->name, cmd->behavior,
                                 cmd->recurse, false,
                                 cmd->missing_ok, lockmode);
            break;
        case AT_AlterColumnType:    /* ALTER COLUMN TYPE */
            /* parse transformation was done earlier */
            address = ATExecAlterColumnType(tab, rel, cmd, lockmode);
            break;
        case AT_AlterColumnGenericOptions:  /* ALTER COLUMN OPTIONS */
            address =
                ATExecAlterColumnGenericOptions(rel, cmd->name,
                                                (List *) cmd->def, lockmode);
            break;
        case AT_ChangeOwner:    /* ALTER OWNER */
            ATExecChangeOwner(RelationGetRelid(rel),
                              get_rolespec_oid(cmd->newowner, false),
                              false, lockmode);
            break;
        case AT_ClusterOn:      /* CLUSTER ON */
            address = ATExecClusterOn(rel, cmd->name, lockmode);
            break;
        case AT_DropCluster:    /* SET WITHOUT CLUSTER */
            ATExecDropCluster(rel, lockmode);
            break;
        case AT_SetLogged:      /* SET LOGGED */
        case AT_SetUnLogged:    /* SET UNLOGGED */
            break;
        case AT_DropOids:       /* SET WITHOUT OIDS */
            /* nothing to do here, oid columns don't exist anymore */
            break;
        case AT_SetAccessMethod:    /* SET ACCESS METHOD */
 
            /*
             * Only do this for partitioned tables, for which this is just a
             * catalog change.  Tables with storage are handled by Phase 3.
             */
            if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
                tab->chgAccessMethod)
                ATExecSetAccessMethodNoStorage(rel, tab->newAccessMethod);
            break;
        case AT_SetTableSpace:  /* SET TABLESPACE */
 
            /*
             * Only do this for partitioned tables and indexes, for which this
             * is just a catalog change.  Other relation types which have
             * storage are handled by Phase 3.
             */
            if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ||
                rel->rd_rel->relkind == RELKIND_PARTITIONED_INDEX)
                ATExecSetTableSpaceNoStorage(rel, tab->newTableSpace);
 
            break;
        case AT_SetRelOptions:  /* SET (...) */
        case AT_ResetRelOptions:    /* RESET (...) */
        case AT_ReplaceRelOptions:  /* replace entire option list */
            ATExecSetRelOptions(rel, (List *) cmd->def, cmd->subtype, lockmode);
            break;
        case AT_EnableTrig:     /* ENABLE TRIGGER name */
            ATExecEnableDisableTrigger(rel, cmd->name,
                                       TRIGGER_FIRES_ON_ORIGIN, false,
                                       cmd->recurse,
                                       lockmode);
            break;
        case AT_EnableAlwaysTrig:   /* ENABLE ALWAYS TRIGGER name */
            ATExecEnableDisableTrigger(rel, cmd->name,
                                       TRIGGER_FIRES_ALWAYS, false,
                                       cmd->recurse,
                                       lockmode);
            break;
        case AT_EnableReplicaTrig:  /* ENABLE REPLICA TRIGGER name */
            ATExecEnableDisableTrigger(rel, cmd->name,
                                       TRIGGER_FIRES_ON_REPLICA, false,
                                       cmd->recurse,
                                       lockmode);
            break;
        case AT_DisableTrig:    /* DISABLE TRIGGER name */
            ATExecEnableDisableTrigger(rel, cmd->name,
                                       TRIGGER_DISABLED, false,
                                       cmd->recurse,
                                       lockmode);
            break;
        case AT_EnableTrigAll:  /* ENABLE TRIGGER ALL */
            ATExecEnableDisableTrigger(rel, NULL,
                                       TRIGGER_FIRES_ON_ORIGIN, false,
                                       cmd->recurse,
                                       lockmode);
            break;
        case AT_DisableTrigAll: /* DISABLE TRIGGER ALL */
            ATExecEnableDisableTrigger(rel, NULL,
                                       TRIGGER_DISABLED, false,
                                       cmd->recurse,
                                       lockmode);
            break;
        case AT_EnableTrigUser: /* ENABLE TRIGGER USER */
            ATExecEnableDisableTrigger(rel, NULL,
                                       TRIGGER_FIRES_ON_ORIGIN, true,
                                       cmd->recurse,
                                       lockmode);
            break;
        case AT_DisableTrigUser:    /* DISABLE TRIGGER USER */
            ATExecEnableDisableTrigger(rel, NULL,
                                       TRIGGER_DISABLED, true,
                                       cmd->recurse,
                                       lockmode);
            break;
 
        case AT_EnableRule:     /* ENABLE RULE name */
            ATExecEnableDisableRule(rel, cmd->name,
                                    RULE_FIRES_ON_ORIGIN, lockmode);
            break;
        case AT_EnableAlwaysRule:   /* ENABLE ALWAYS RULE name */
            ATExecEnableDisableRule(rel, cmd->name,
                                    RULE_FIRES_ALWAYS, lockmode);
            break;
        case AT_EnableReplicaRule:  /* ENABLE REPLICA RULE name */
            ATExecEnableDisableRule(rel, cmd->name,
                                    RULE_FIRES_ON_REPLICA, lockmode);
            break;
        case AT_DisableRule:    /* DISABLE RULE name */
            ATExecEnableDisableRule(rel, cmd->name,
                                    RULE_DISABLED, lockmode);
            break;
 
        case AT_AddInherit:
            address = ATExecAddInherit(rel, (RangeVar *) cmd->def, lockmode);
            break;
        case AT_DropInherit:
            address = ATExecDropInherit(rel, (RangeVar *) cmd->def, lockmode);
            break;
        case AT_AddOf:
            address = ATExecAddOf(rel, (TypeName *) cmd->def, lockmode);
            break;
        case AT_DropOf:
            ATExecDropOf(rel, lockmode);
            break;
        case AT_ReplicaIdentity:
            ATExecReplicaIdentity(rel, (ReplicaIdentityStmt *) cmd->def, lockmode);
            break;
        case AT_EnableRowSecurity:
            ATExecSetRowSecurity(rel, true);
            break;
        case AT_DisableRowSecurity:
            ATExecSetRowSecurity(rel, false);
            break;
        case AT_ForceRowSecurity:
            ATExecForceNoForceRowSecurity(rel, true);
            break;
        case AT_NoForceRowSecurity:
            ATExecForceNoForceRowSecurity(rel, false);
            break;
        case AT_GenericOptions:
            ATExecGenericOptions(rel, (List *) cmd->def);
            break;
        case AT_AttachPartition:
            cmd = ATParseTransformCmd(wqueue, tab, rel, cmd, false, lockmode,
                                      cur_pass, context);
            Assert(cmd != NULL);
            if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
                address = ATExecAttachPartition(wqueue, rel, (PartitionCmd *) cmd->def,
                                                context);
            else
                address = ATExecAttachPartitionIdx(wqueue, rel,
                                                   ((PartitionCmd *) cmd->def)->name);
            break;
        case AT_DetachPartition:
            cmd = ATParseTransformCmd(wqueue, tab, rel, cmd, false, lockmode,
                                      cur_pass, context);
            Assert(cmd != NULL);
            /* ATPrepCmd ensures it must be a table */
            Assert(rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
            address = ATExecDetachPartition(wqueue, tab, rel,
                                            ((PartitionCmd *) cmd->def)->name,
                                            ((PartitionCmd *) cmd->def)->concurrent);
            break;
        case AT_DetachPartitionFinalize:
            address = ATExecDetachPartitionFinalize(rel, ((PartitionCmd *) cmd->def)->name);
            break;
        default:                /* oops */
            elog(ERROR, "unrecognized alter table type: %d",
                 (int) cmd->subtype);
            break;
    }
 
    /*
     * Report the subcommand to interested event triggers.
     */
    if (cmd)
        EventTriggerCollectAlterTableSubcmd((Node *) cmd, address);
 
    /*
     * Bump the command counter to ensure the next subcommand in the sequence
     * can see the changes so far
     */
    CommandCounterIncrement();
}
 
/*
 * ATParseTransformCmd: perform parse transformation for one subcommand
 *
 * Returns the transformed subcommand tree, if there is one, else NULL.
 *
 * The parser may hand back additional AlterTableCmd(s) and/or other
 * utility statements, either before or after the original subcommand.
 * Other AlterTableCmds are scheduled into the appropriate slot of the
 * AlteredTableInfo (they had better be for later passes than the current one).
 * Utility statements that are supposed to happen before the AlterTableCmd
 * are executed immediately.  Those that are supposed to happen afterwards
 * are added to the tab->afterStmts list to be done at the very end.
 */
static AlterTableCmd *
ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
                    AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode,
                    AlterTablePass cur_pass, AlterTableUtilityContext *context)
{
    AlterTableCmd *newcmd = NULL;
    AlterTableStmt *atstmt = makeNode(AlterTableStmt);
    List       *beforeStmts;
    List       *afterStmts;
    ListCell   *lc;
 
    /* Gin up an AlterTableStmt with just this subcommand and this table */
    atstmt->relation =
        makeRangeVar(get_namespace_name(RelationGetNamespace(rel)),
                     pstrdup(RelationGetRelationName(rel)),
                     -1);
    atstmt->relation->inh = recurse;
    atstmt->cmds = list_make1(cmd);
    atstmt->objtype = OBJECT_TABLE; /* needn't be picky here */
    atstmt->missing_ok = false;
 
    /* Transform the AlterTableStmt */
    atstmt = transformAlterTableStmt(RelationGetRelid(rel),
                                     atstmt,
                                     context->queryString,
                                     &beforeStmts,
                                     &afterStmts);
 
    /* Execute any statements that should happen before these subcommand(s) */
    foreach(lc, beforeStmts)
    {
        Node       *stmt = (Node *) lfirst(lc);
 
        ProcessUtilityForAlterTable(stmt, context);
        CommandCounterIncrement();
    }
 
    /* Examine the transformed subcommands and schedule them appropriately */
    foreach(lc, atstmt->cmds)
    {
        AlterTableCmd *cmd2 = lfirst_node(AlterTableCmd, lc);
        AlterTablePass pass;
 
        /*
         * This switch need only cover the subcommand types that can be added
         * by parse_utilcmd.c; otherwise, we'll use the default strategy of
         * executing the subcommand immediately, as a substitute for the
         * original subcommand.  (Note, however, that this does cause
         * AT_AddConstraint subcommands to be rescheduled into later passes,
         * which is important for index and foreign key constraints.)
         *
         * We assume we needn't do any phase-1 checks for added subcommands.
         */
        switch (cmd2->subtype)
        {
            case AT_SetNotNull:
                /* Need command-specific recursion decision */
                ATPrepSetNotNull(wqueue, rel, cmd2,
                                 recurse, false,
                                 lockmode, context);
                pass = AT_PASS_COL_ATTRS;
                break;
            case AT_AddIndex:
                /* This command never recurses */
                /* No command-specific prep needed */
                pass = AT_PASS_ADD_INDEX;
                break;
            case AT_AddIndexConstraint:
                /* This command never recurses */
                /* No command-specific prep needed */
                pass = AT_PASS_ADD_INDEXCONSTR;
                break;
            case AT_AddConstraint:
                /* Recursion occurs during execution phase */
                if (recurse)
                    cmd2->recurse = true;
                switch (castNode(Constraint, cmd2->def)->contype)
                {
                    case CONSTR_PRIMARY:
                    case CONSTR_UNIQUE:
                    case CONSTR_EXCLUSION:
                        pass = AT_PASS_ADD_INDEXCONSTR;
                        break;
                    default:
                        pass = AT_PASS_ADD_OTHERCONSTR;
                        break;
                }
                break;
            case AT_AlterColumnGenericOptions:
                /* This command never recurses */
                /* No command-specific prep needed */
                pass = AT_PASS_MISC;
                break;
            default:
                pass = cur_pass;
                break;
        }
 
        if (pass < cur_pass)
        {
            /* Cannot schedule into a pass we already finished */
            elog(ERROR, "ALTER TABLE scheduling failure: too late for pass %d",
                 pass);
        }
        else if (pass > cur_pass)
        {
            /* OK, queue it up for later */
            tab->subcmds[pass] = lappend(tab->subcmds[pass], cmd2);
        }
        else
        {
            /*
             * We should see at most one subcommand for the current pass,
             * which is the transformed version of the original subcommand.
             */
            if (newcmd == NULL && cmd->subtype == cmd2->subtype)
            {
                /* Found the transformed version of our subcommand */
                newcmd = cmd2;
            }
            else
                elog(ERROR, "ALTER TABLE scheduling failure: bogus item for pass %d",
                     pass);
        }
    }
 
    /* Queue up any after-statements to happen at the end */
    tab->afterStmts = list_concat(tab->afterStmts, afterStmts);
 
    return newcmd;
}
 
/*
 * ATRewriteTables: ALTER TABLE phase 3
 */
static void
ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
                AlterTableUtilityContext *context)
{
    ListCell   *ltab;
 
    /* Go through each table that needs to be checked or rewritten */
    foreach(ltab, *wqueue)
    {
        AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 
        /* Relations without storage may be ignored here */
        if (!RELKIND_HAS_STORAGE(tab->relkind))
            continue;
 
        /*
         * If we change column data types, the operation has to be propagated
         * to tables that use this table's rowtype as a column type.
         * tab->newvals will also be non-NULL in the case where we're adding a
         * column with a default.  We choose to forbid that case as well,
         * since composite types might eventually support defaults.
         *
         * (Eventually we'll probably need to check for composite type
         * dependencies even when we're just scanning the table without a
         * rewrite, but at the moment a composite type does not enforce any
         * constraints, so it's not necessary/appropriate to enforce them just
         * during ALTER.)
         */
        if (tab->newvals != NIL || tab->rewrite > 0)
        {
            Relation    rel;
 
            rel = table_open(tab->relid, NoLock);
            find_composite_type_dependencies(rel->rd_rel->reltype, rel, NULL);
            table_close(rel, NoLock);
        }
 
        /*
         * We only need to rewrite the table if at least one column needs to
         * be recomputed, or we are changing its persistence or access method.
         *
         * There are two reasons for requiring a rewrite when changing
         * persistence: on one hand, we need to ensure that the buffers
         * belonging to each of the two relations are marked with or without
         * BM_PERMANENT properly.  On the other hand, since rewriting creates
         * and assigns a new relfilenumber, we automatically create or drop an
         * init fork for the relation as appropriate.
         */
        if (tab->rewrite > 0 && tab->relkind != RELKIND_SEQUENCE)
        {
            /* Build a temporary relation and copy data */
            Relation    OldHeap;
            Oid         OIDNewHeap;
            Oid         NewAccessMethod;
            Oid         NewTableSpace;
            char        persistence;
 
            OldHeap = table_open(tab->relid, NoLock);
 
            /*
             * We don't support rewriting of system catalogs; there are too
             * many corner cases and too little benefit.  In particular this
             * is certainly not going to work for mapped catalogs.
             */
            if (IsSystemRelation(OldHeap))
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot rewrite system relation \"%s\"",
                                RelationGetRelationName(OldHeap))));
 
            if (RelationIsUsedAsCatalogTable(OldHeap))
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot rewrite table \"%s\" used as a catalog table",
                                RelationGetRelationName(OldHeap))));
 
            /*
             * Don't allow rewrite on temp tables of other backends ... their
             * local buffer manager is not going to cope.  (This is redundant
             * with the check in CheckAlterTableIsSafe, but for safety we'll
             * check here too.)
             */
            if (RELATION_IS_OTHER_TEMP(OldHeap))
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot rewrite temporary tables of other sessions")));
 
            /*
             * Select destination tablespace (same as original unless user
             * requested a change)
             */
            if (tab->newTableSpace)
                NewTableSpace = tab->newTableSpace;
            else
                NewTableSpace = OldHeap->rd_rel->reltablespace;
 
            /*
             * Select destination access method (same as original unless user
             * requested a change)
             */
            if (tab->chgAccessMethod)
                NewAccessMethod = tab->newAccessMethod;
            else
                NewAccessMethod = OldHeap->rd_rel->relam;
 
            /*
             * Select persistence of transient table (same as original unless
             * user requested a change)
             */
            persistence = tab->chgPersistence ?
                tab->newrelpersistence : OldHeap->rd_rel->relpersistence;
 
            table_close(OldHeap, NoLock);
 
            /*
             * Fire off an Event Trigger now, before actually rewriting the
             * table.
             *
             * We don't support Event Trigger for nested commands anywhere,
             * here included, and parsetree is given NULL when coming from
             * AlterTableInternal.
             *
             * And fire it only once.
             */
            if (parsetree)
                EventTriggerTableRewrite((Node *) parsetree,
                                         tab->relid,
                                         tab->rewrite);
 
            /*
             * Create transient table that will receive the modified data.
             *
             * Ensure it is marked correctly as logged or unlogged.  We have
             * to do this here so that buffers for the new relfilenumber will
             * have the right persistence set, and at the same time ensure
             * that the original filenumbers's buffers will get read in with
             * the correct setting (i.e. the original one).  Otherwise a
             * rollback after the rewrite would possibly result with buffers
             * for the original filenumbers having the wrong persistence
             * setting.
             *
             * NB: This relies on swap_relation_files() also swapping the
             * persistence. That wouldn't work for pg_class, but that can't be
             * unlogged anyway.
             */
            OIDNewHeap = make_new_heap(tab->relid, NewTableSpace, NewAccessMethod,
                                       persistence, lockmode);
 
            /*
             * Copy the heap data into the new table with the desired
             * modifications, and test the current data within the table
             * against new constraints generated by ALTER TABLE commands.
             */
            ATRewriteTable(tab, OIDNewHeap, lockmode);
 
            /*
             * Swap the physical files of the old and new heaps, then rebuild
             * indexes and discard the old heap.  We can use RecentXmin for
             * the table's new relfrozenxid because we rewrote all the tuples
             * in ATRewriteTable, so no older Xid remains in the table.  Also,
             * we never try to swap toast tables by content, since we have no
             * interest in letting this code work on system catalogs.
             */
            finish_heap_swap(tab->relid, OIDNewHeap,
                             false, false, true,
                             !OidIsValid(tab->newTableSpace),
                             RecentXmin,
                             ReadNextMultiXactId(),
                             persistence);
 
            InvokeObjectPostAlterHook(RelationRelationId, tab->relid, 0);
        }
        else if (tab->rewrite > 0 && tab->relkind == RELKIND_SEQUENCE)
        {
            if (tab->chgPersistence)
                SequenceChangePersistence(tab->relid, tab->newrelpersistence);
        }
        else
        {
            /*
             * If required, test the current data within the table against new
             * constraints generated by ALTER TABLE commands, but don't
             * rebuild data.
             */
            if (tab->constraints != NIL || tab->verify_new_notnull ||
                tab->partition_constraint != NULL)
                ATRewriteTable(tab, InvalidOid, lockmode);
 
            /*
             * If we had SET TABLESPACE but no reason to reconstruct tuples,
             * just do a block-by-block copy.
             */
            if (tab->newTableSpace)
                ATExecSetTableSpace(tab->relid, tab->newTableSpace, lockmode);
        }
 
        /*
         * Also change persistence of owned sequences, so that it matches the
         * table persistence.
         */
        if (tab->chgPersistence)
        {
            List       *seqlist = getOwnedSequences(tab->relid);
            ListCell   *lc;
 
            foreach(lc, seqlist)
            {
                Oid         seq_relid = lfirst_oid(lc);
 
                SequenceChangePersistence(seq_relid, tab->newrelpersistence);
            }
        }
    }
 
    /*
     * Foreign key constraints are checked in a final pass, since (a) it's
     * generally best to examine each one separately, and (b) it's at least
     * theoretically possible that we have changed both relations of the
     * foreign key, and we'd better have finished both rewrites before we try
     * to read the tables.
     */
    foreach(ltab, *wqueue)
    {
        AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
        Relation    rel = NULL;
        ListCell   *lcon;
 
        /* Relations without storage may be ignored here too */
        if (!RELKIND_HAS_STORAGE(tab->relkind))
            continue;
 
        foreach(lcon, tab->constraints)
        {
            NewConstraint *con = lfirst(lcon);
 
            if (con->contype == CONSTR_FOREIGN)
            {
                Constraint *fkconstraint = (Constraint *) con->qual;
                Relation    refrel;
 
                if (rel == NULL)
                {
                    /* Long since locked, no need for another */
                    rel = table_open(tab->relid, NoLock);
                }
 
                refrel = table_open(con->refrelid, RowShareLock);
 
                validateForeignKeyConstraint(fkconstraint->conname, rel, refrel,
                                             con->refindid,
                                             con->conid,
                                             con->conwithperiod);
 
                /*
                 * No need to mark the constraint row as validated, we did
                 * that when we inserted the row earlier.
                 */
 
                table_close(refrel, NoLock);
            }
        }
 
        if (rel)
            table_close(rel, NoLock);
    }
 
    /* Finally, run any afterStmts that were queued up */
    foreach(ltab, *wqueue)
    {
        AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
        ListCell   *lc;
 
        foreach(lc, tab->afterStmts)
        {
            Node       *stmt = (Node *) lfirst(lc);
 
            ProcessUtilityForAlterTable(stmt, context);
            CommandCounterIncrement();
        }
    }
}
 
/*
 * ATRewriteTable: scan or rewrite one table
 *
 * OIDNewHeap is InvalidOid if we don't need to rewrite
 */
static void
ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
{
    Relation    oldrel;
    Relation    newrel;
    TupleDesc   oldTupDesc;
    TupleDesc   newTupDesc;
    bool        needscan = false;
    List       *notnull_attrs;
    int         i;
    ListCell   *l;
    EState     *estate;
    CommandId   mycid;
    BulkInsertState bistate;
    int         ti_options;
    ExprState  *partqualstate = NULL;
 
    /*
     * Open the relation(s).  We have surely already locked the existing
     * table.
     */
    oldrel = table_open(tab->relid, NoLock);
    oldTupDesc = tab->oldDesc;
    newTupDesc = RelationGetDescr(oldrel);  /* includes all mods */
 
    if (OidIsValid(OIDNewHeap))
        newrel = table_open(OIDNewHeap, lockmode);
    else
        newrel = NULL;
 
    /*
     * Prepare a BulkInsertState and options for table_tuple_insert.  The FSM
     * is empty, so don't bother using it.
     */
    if (newrel)
    {
        mycid = GetCurrentCommandId(true);
        bistate = GetBulkInsertState();
        ti_options = TABLE_INSERT_SKIP_FSM;
    }
    else
    {
        /* keep compiler quiet about using these uninitialized */
        mycid = 0;
        bistate = NULL;
        ti_options = 0;
    }
 
    /*
     * Generate the constraint and default execution states
     */
 
    estate = CreateExecutorState();
 
    /* Build the needed expression execution states */
    foreach(l, tab->constraints)
    {
        NewConstraint *con = lfirst(l);
 
        switch (con->contype)
        {
            case CONSTR_CHECK:
                needscan = true;
                con->qualstate = ExecPrepareExpr((Expr *) con->qual, estate);
                break;
            case CONSTR_FOREIGN:
                /* Nothing to do here */
                break;
            default:
                elog(ERROR, "unrecognized constraint type: %d",
                     (int) con->contype);
        }
    }
 
    /* Build expression execution states for partition check quals */
    if (tab->partition_constraint)
    {
        needscan = true;
        partqualstate = ExecPrepareExpr(tab->partition_constraint, estate);
    }
 
    foreach(l, tab->newvals)
    {
        NewColumnValue *ex = lfirst(l);
 
        /* expr already planned */
        ex->exprstate = ExecInitExpr((Expr *) ex->expr, NULL);
    }
 
    notnull_attrs = NIL;
    if (newrel || tab->verify_new_notnull)
    {
        /*
         * If we are rebuilding the tuples OR if we added any new but not
         * verified not-null constraints, check all not-null constraints. This
         * is a bit of overkill but it minimizes risk of bugs, and
         * heap_attisnull is a pretty cheap test anyway.
         */
        for (i = 0; i < newTupDesc->natts; i++)
        {
            Form_pg_attribute attr = TupleDescAttr(newTupDesc, i);
 
            if (attr->attnotnull && !attr->attisdropped)
                notnull_attrs = lappend_int(notnull_attrs, i);
        }
        if (notnull_attrs)
            needscan = true;
    }
 
    if (newrel || needscan)
    {
        ExprContext *econtext;
        TupleTableSlot *oldslot;
        TupleTableSlot *newslot;
        TableScanDesc scan;
        MemoryContext oldCxt;
        List       *dropped_attrs = NIL;
        ListCell   *lc;
        Snapshot    snapshot;
 
        if (newrel)
            ereport(DEBUG1,
                    (errmsg_internal("rewriting table \"%s\"",
                                     RelationGetRelationName(oldrel))));
        else
            ereport(DEBUG1,
                    (errmsg_internal("verifying table \"%s\"",
                                     RelationGetRelationName(oldrel))));
 
        if (newrel)
        {
            /*
             * All predicate locks on the tuples or pages are about to be made
             * invalid, because we move tuples around.  Promote them to
             * relation locks.
             */
            TransferPredicateLocksToHeapRelation(oldrel);
        }
 
        econtext = GetPerTupleExprContext(estate);
 
        /*
         * Create necessary tuple slots. When rewriting, two slots are needed,
         * otherwise one suffices. In the case where one slot suffices, we
         * need to use the new tuple descriptor, otherwise some constraints
         * can't be evaluated.  Note that even when the tuple layout is the
         * same and no rewrite is required, the tupDescs might not be
         * (consider ADD COLUMN without a default).
         */
        if (tab->rewrite)
        {
            Assert(newrel != NULL);
            oldslot = MakeSingleTupleTableSlot(oldTupDesc,
                                               table_slot_callbacks(oldrel));
            newslot = MakeSingleTupleTableSlot(newTupDesc,
                                               table_slot_callbacks(newrel));
 
            /*
             * Set all columns in the new slot to NULL initially, to ensure
             * columns added as part of the rewrite are initialized to NULL.
             * That is necessary as tab->newvals will not contain an
             * expression for columns with a NULL default, e.g. when adding a
             * column without a default together with a column with a default
             * requiring an actual rewrite.
             */
            ExecStoreAllNullTuple(newslot);
        }
        else
        {
            oldslot = MakeSingleTupleTableSlot(newTupDesc,
                                               table_slot_callbacks(oldrel));
            newslot = NULL;
        }
 
        /*
         * Any attributes that are dropped according to the new tuple
         * descriptor can be set to NULL. We precompute the list of dropped
         * attributes to avoid needing to do so in the per-tuple loop.
         */
        for (i = 0; i < newTupDesc->natts; i++)
        {
            if (TupleDescAttr(newTupDesc, i)->attisdropped)
                dropped_attrs = lappend_int(dropped_attrs, i);
        }
 
        /*
         * Scan through the rows, generating a new row if needed and then
         * checking all the constraints.
         */
        snapshot = RegisterSnapshot(GetLatestSnapshot());
        scan = table_beginscan(oldrel, snapshot, 0, NULL);
 
        /*
         * Switch to per-tuple memory context and reset it for each tuple
         * produced, so we don't leak memory.
         */
        oldCxt = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
 
        while (table_scan_getnextslot(scan, ForwardScanDirection, oldslot))
        {
            TupleTableSlot *insertslot;
 
            if (tab->rewrite > 0)
            {
                /* Extract data from old tuple */
                slot_getallattrs(oldslot);
                ExecClearTuple(newslot);
 
                /* copy attributes */
                memcpy(newslot->tts_values, oldslot->tts_values,
                       sizeof(Datum) * oldslot->tts_nvalid);
                memcpy(newslot->tts_isnull, oldslot->tts_isnull,
                       sizeof(bool) * oldslot->tts_nvalid);
 
                /* Set dropped attributes to null in new tuple */
                foreach(lc, dropped_attrs)
                    newslot->tts_isnull[lfirst_int(lc)] = true;
 
                /*
                 * Constraints and GENERATED expressions might reference the
                 * tableoid column, so fill tts_tableOid with the desired
                 * value.  (We must do this each time, because it gets
                 * overwritten with newrel's OID during storing.)
                 */
                newslot->tts_tableOid = RelationGetRelid(oldrel);
 
                /*
                 * Process supplied expressions to replace selected columns.
                 *
                 * First, evaluate expressions whose inputs come from the old
                 * tuple.
                 */
                econtext->ecxt_scantuple = oldslot;
 
                foreach(l, tab->newvals)
                {
                    NewColumnValue *ex = lfirst(l);
 
                    if (ex->is_generated)
                        continue;
 
                    newslot->tts_values[ex->attnum - 1]
                        = ExecEvalExpr(ex->exprstate,
                                       econtext,
                                       &newslot->tts_isnull[ex->attnum - 1]);
                }
 
                ExecStoreVirtualTuple(newslot);
 
                /*
                 * Now, evaluate any expressions whose inputs come from the
                 * new tuple.  We assume these columns won't reference each
                 * other, so that there's no ordering dependency.
                 */
                econtext->ecxt_scantuple = newslot;
 
                foreach(l, tab->newvals)
                {
                    NewColumnValue *ex = lfirst(l);
 
                    if (!ex->is_generated)
                        continue;
 
                    newslot->tts_values[ex->attnum - 1]
                        = ExecEvalExpr(ex->exprstate,
                                       econtext,
                                       &newslot->tts_isnull[ex->attnum - 1]);
                }
 
                insertslot = newslot;
            }
            else
            {
                /*
                 * If there's no rewrite, old and new table are guaranteed to
                 * have the same AM, so we can just use the old slot to verify
                 * new constraints etc.
                 */
                insertslot = oldslot;
            }
 
            /* Now check any constraints on the possibly-changed tuple */
            econtext->ecxt_scantuple = insertslot;
 
            foreach(l, notnull_attrs)
            {
                int         attn = lfirst_int(l);
 
                if (slot_attisnull(insertslot, attn + 1))
                {
                    Form_pg_attribute attr = TupleDescAttr(newTupDesc, attn);
 
                    ereport(ERROR,
                            (errcode(ERRCODE_NOT_NULL_VIOLATION),
                             errmsg("column \"%s\" of relation \"%s\" contains null values",
                                    NameStr(attr->attname),
                                    RelationGetRelationName(oldrel)),
                             errtablecol(oldrel, attn + 1)));
                }
            }
 
            foreach(l, tab->constraints)
            {
                NewConstraint *con = lfirst(l);
 
                switch (con->contype)
                {
                    case CONSTR_CHECK:
                        if (!ExecCheck(con->qualstate, econtext))
                            ereport(ERROR,
                                    (errcode(ERRCODE_CHECK_VIOLATION),
                                     errmsg("check constraint \"%s\" of relation \"%s\" is violated by some row",
                                            con->name,
                                            RelationGetRelationName(oldrel)),
                                     errtableconstraint(oldrel, con->name)));
                        break;
                    case CONSTR_FOREIGN:
                        /* Nothing to do here */
                        break;
                    default:
                        elog(ERROR, "unrecognized constraint type: %d",
                             (int) con->contype);
                }
            }
 
            if (partqualstate && !ExecCheck(partqualstate, econtext))
            {
                if (tab->validate_default)
                    ereport(ERROR,
                            (errcode(ERRCODE_CHECK_VIOLATION),
                             errmsg("updated partition constraint for default partition \"%s\" would be violated by some row",
                                    RelationGetRelationName(oldrel)),
                             errtable(oldrel)));
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_CHECK_VIOLATION),
                             errmsg("partition constraint of relation \"%s\" is violated by some row",
                                    RelationGetRelationName(oldrel)),
                             errtable(oldrel)));
            }
 
            /* Write the tuple out to the new relation */
            if (newrel)
                table_tuple_insert(newrel, insertslot, mycid,
                                   ti_options, bistate);
 
            ResetExprContext(econtext);
 
            CHECK_FOR_INTERRUPTS();
        }
 
        MemoryContextSwitchTo(oldCxt);
        table_endscan(scan);
        UnregisterSnapshot(snapshot);
 
        ExecDropSingleTupleTableSlot(oldslot);
        if (newslot)
            ExecDropSingleTupleTableSlot(newslot);
    }
 
    FreeExecutorState(estate);
 
    table_close(oldrel, NoLock);
    if (newrel)
    {
        FreeBulkInsertState(bistate);
 
        table_finish_bulk_insert(newrel, ti_options);
 
        table_close(newrel, NoLock);
    }
}
 
/*
 * ATGetQueueEntry: find or create an entry in the ALTER TABLE work queue
 */
static AlteredTableInfo *
ATGetQueueEntry(List **wqueue, Relation rel)
{
    Oid         relid = RelationGetRelid(rel);
    AlteredTableInfo *tab;
    ListCell   *ltab;
 
    foreach(ltab, *wqueue)
    {
        tab = (AlteredTableInfo *) lfirst(ltab);
        if (tab->relid == relid)
            return tab;
    }
 
    /*
     * Not there, so add it.  Note that we make a copy of the relation's
     * existing descriptor before anything interesting can happen to it.
     */
    tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
    tab->relid = relid;
    tab->rel = NULL;            /* set later */
    tab->relkind = rel->rd_rel->relkind;
    tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
    tab->newAccessMethod = InvalidOid;
    tab->chgAccessMethod = false;
    tab->newTableSpace = InvalidOid;
    tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
    tab->chgPersistence = false;
 
    *wqueue = lappend(*wqueue, tab);
 
    return tab;
}
 
static const char *
alter_table_type_to_string(AlterTableType cmdtype)
{
    switch (cmdtype)
    {
        case AT_AddColumn:
        case AT_AddColumnToView:
            return "ADD COLUMN";
        case AT_ColumnDefault:
        case AT_CookedColumnDefault:
            return "ALTER COLUMN ... SET DEFAULT";
        case AT_DropNotNull:
            return "ALTER COLUMN ... DROP NOT NULL";
        case AT_SetNotNull:
            return "ALTER COLUMN ... SET NOT NULL";
        case AT_SetExpression:
            return "ALTER COLUMN ... SET EXPRESSION";
        case AT_DropExpression:
            return "ALTER COLUMN ... DROP EXPRESSION";
        case AT_CheckNotNull:
            return NULL;        /* not real grammar */
        case AT_SetStatistics:
            return "ALTER COLUMN ... SET STATISTICS";
        case AT_SetOptions:
            return "ALTER COLUMN ... SET";
        case AT_ResetOptions:
            return "ALTER COLUMN ... RESET";
        case AT_SetStorage:
            return "ALTER COLUMN ... SET STORAGE";
        case AT_SetCompression:
            return "ALTER COLUMN ... SET COMPRESSION";
        case AT_DropColumn:
            return "DROP COLUMN";
        case AT_AddIndex:
        case AT_ReAddIndex:
            return NULL;        /* not real grammar */
        case AT_AddConstraint:
        case AT_ReAddConstraint:
        case AT_ReAddDomainConstraint:
        case AT_AddIndexConstraint:
            return "ADD CONSTRAINT";
        case AT_AlterConstraint:
            return "ALTER CONSTRAINT";
        case AT_ValidateConstraint:
            return "VALIDATE CONSTRAINT";
        case AT_DropConstraint:
            return "DROP CONSTRAINT";
        case AT_ReAddComment:
            return NULL;        /* not real grammar */
        case AT_AlterColumnType:
            return "ALTER COLUMN ... SET DATA TYPE";
        case AT_AlterColumnGenericOptions:
            return "ALTER COLUMN ... OPTIONS";
        case AT_ChangeOwner:
            return "OWNER TO";
        case AT_ClusterOn:
            return "CLUSTER ON";
        case AT_DropCluster:
            return "SET WITHOUT CLUSTER";
        case AT_SetAccessMethod:
            return "SET ACCESS METHOD";
        case AT_SetLogged:
            return "SET LOGGED";
        case AT_SetUnLogged:
            return "SET UNLOGGED";
        case AT_DropOids:
            return "SET WITHOUT OIDS";
        case AT_SetTableSpace:
            return "SET TABLESPACE";
        case AT_SetRelOptions:
            return "SET";
        case AT_ResetRelOptions:
            return "RESET";
        case AT_ReplaceRelOptions:
            return NULL;        /* not real grammar */
        case AT_EnableTrig:
            return "ENABLE TRIGGER";
        case AT_EnableAlwaysTrig:
            return "ENABLE ALWAYS TRIGGER";
        case AT_EnableReplicaTrig:
            return "ENABLE REPLICA TRIGGER";
        case AT_DisableTrig:
            return "DISABLE TRIGGER";
        case AT_EnableTrigAll:
            return "ENABLE TRIGGER ALL";
        case AT_DisableTrigAll:
            return "DISABLE TRIGGER ALL";
        case AT_EnableTrigUser:
            return "ENABLE TRIGGER USER";
        case AT_DisableTrigUser:
            return "DISABLE TRIGGER USER";
        case AT_EnableRule:
            return "ENABLE RULE";
        case AT_EnableAlwaysRule:
            return "ENABLE ALWAYS RULE";
        case AT_EnableReplicaRule:
            return "ENABLE REPLICA RULE";
        case AT_DisableRule:
            return "DISABLE RULE";
        case AT_AddInherit:
            return "INHERIT";
        case AT_DropInherit:
            return "NO INHERIT";
        case AT_AddOf:
            return "OF";
        case AT_DropOf:
            return "NOT OF";
        case AT_ReplicaIdentity:
            return "REPLICA IDENTITY";
        case AT_EnableRowSecurity:
            return "ENABLE ROW SECURITY";
        case AT_DisableRowSecurity:
            return "DISABLE ROW SECURITY";
        case AT_ForceRowSecurity:
            return "FORCE ROW SECURITY";
        case AT_NoForceRowSecurity:
            return "NO FORCE ROW SECURITY";
        case AT_GenericOptions:
            return "OPTIONS";
        case AT_AttachPartition:
            return "ATTACH PARTITION";
        case AT_DetachPartition:
            return "DETACH PARTITION";
        case AT_DetachPartitionFinalize:
            return "DETACH PARTITION ... FINALIZE";
        case AT_AddIdentity:
            return "ALTER COLUMN ... ADD IDENTITY";
        case AT_SetIdentity:
            return "ALTER COLUMN ... SET";
        case AT_DropIdentity:
            return "ALTER COLUMN ... DROP IDENTITY";
        case AT_ReAddStatistics:
            return NULL;        /* not real grammar */
    }
 
    return NULL;
}
 
/*
 * ATSimplePermissions
 *
 * - Ensure that it is a relation (or possibly a view)
 * - Ensure this user is the owner
 * - Ensure that it is not a system table
 */
static void
ATSimplePermissions(AlterTableType cmdtype, Relation rel, int allowed_targets)
{
    int         actual_target;
 
    switch (rel->rd_rel->relkind)
    {
        case RELKIND_RELATION:
            actual_target = ATT_TABLE;
            break;
        case RELKIND_PARTITIONED_TABLE:
            actual_target = ATT_PARTITIONED_TABLE;
            break;
        case RELKIND_VIEW:
            actual_target = ATT_VIEW;
            break;
        case RELKIND_MATVIEW:
            actual_target = ATT_MATVIEW;
            break;
        case RELKIND_INDEX:
            actual_target = ATT_INDEX;
            break;
        case RELKIND_PARTITIONED_INDEX:
            actual_target = ATT_PARTITIONED_INDEX;
            break;
        case RELKIND_COMPOSITE_TYPE:
            actual_target = ATT_COMPOSITE_TYPE;
            break;
        case RELKIND_FOREIGN_TABLE:
            actual_target = ATT_FOREIGN_TABLE;
            break;
        case RELKIND_SEQUENCE:
            actual_target = ATT_SEQUENCE;
            break;
        default:
            actual_target = 0;
            break;
    }
 
    /* Wrong target type? */
    if ((actual_target & allowed_targets) == 0)
    {
        const char *action_str = alter_table_type_to_string(cmdtype);
 
        if (action_str)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
            /* translator: %s is a group of some SQL keywords */
                     errmsg("ALTER action %s cannot be performed on relation \"%s\"",
                            action_str, RelationGetRelationName(rel)),
                     errdetail_relkind_not_supported(rel->rd_rel->relkind)));
        else
            /* internal error? */
            elog(ERROR, "invalid ALTER action attempted on relation \"%s\"",
                 RelationGetRelationName(rel));
    }
 
    /* Permissions checks */
    if (!object_ownercheck(RelationRelationId, RelationGetRelid(rel), GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(rel->rd_rel->relkind),
                       RelationGetRelationName(rel));
 
    if (!allowSystemTableMods && IsSystemRelation(rel))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: \"%s\" is a system catalog",
                        RelationGetRelationName(rel))));
}
 
/*
 * ATSimpleRecursion
 *
 * Simple table recursion sufficient for most ALTER TABLE operations.
 * All direct and indirect children are processed in an unspecified order.
 * Note that if a child inherits from the original table via multiple
 * inheritance paths, it will be visited just once.
 */
static void
ATSimpleRecursion(List **wqueue, Relation rel,
                  AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode,
                  AlterTableUtilityContext *context)
{
    /*
     * Propagate to children, if desired and if there are (or might be) any
     * children.
     */
    if (recurse && rel->rd_rel->relhassubclass)
    {
        Oid         relid = RelationGetRelid(rel);
        ListCell   *child;
        List       *children;
 
        children = find_all_inheritors(relid, lockmode, NULL);
 
        /*
         * find_all_inheritors does the recursive search of the inheritance
         * hierarchy, so all we have to do is process all of the relids in the
         * list that it returns.
         */
        foreach(child, children)
        {
            Oid         childrelid = lfirst_oid(child);
            Relation    childrel;
 
            if (childrelid == relid)
                continue;
            /* find_all_inheritors already got lock */
            childrel = relation_open(childrelid, NoLock);
            CheckAlterTableIsSafe(childrel);
            ATPrepCmd(wqueue, childrel, cmd, false, true, lockmode, context);
            relation_close(childrel, NoLock);
        }
    }
}
 
/*
 * Obtain list of partitions of the given table, locking them all at the given
 * lockmode and ensuring that they all pass CheckAlterTableIsSafe.
 *
 * This function is a no-op if the given relation is not a partitioned table;
 * in particular, nothing is done if it's a legacy inheritance parent.
 */
static void
ATCheckPartitionsNotInUse(Relation rel, LOCKMODE lockmode)
{
    if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        List       *inh;
        ListCell   *cell;
 
        inh = find_all_inheritors(RelationGetRelid(rel), lockmode, NULL);
        /* first element is the parent rel; must ignore it */
        for_each_from(cell, inh, 1)
        {
            Relation    childrel;
 
            /* find_all_inheritors already got lock */
            childrel = table_open(lfirst_oid(cell), NoLock);
            CheckAlterTableIsSafe(childrel);
            table_close(childrel, NoLock);
        }
        list_free(inh);
    }
}
 
/*
 * ATTypedTableRecursion
 *
 * Propagate ALTER TYPE operations to the typed tables of that type.
 * Also check the RESTRICT/CASCADE behavior.  Given CASCADE, also permit
 * recursion to inheritance children of the typed tables.
 */
static void
ATTypedTableRecursion(List **wqueue, Relation rel, AlterTableCmd *cmd,
                      LOCKMODE lockmode, AlterTableUtilityContext *context)
{
    ListCell   *child;
    List       *children;
 
    Assert(rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE);
 
    children = find_typed_table_dependencies(rel->rd_rel->reltype,
                                             RelationGetRelationName(rel),
                                             cmd->behavior);
 
    foreach(child, children)
    {
        Oid         childrelid = lfirst_oid(child);
        Relation    childrel;
 
        childrel = relation_open(childrelid, lockmode);
        CheckAlterTableIsSafe(childrel);
        ATPrepCmd(wqueue, childrel, cmd, true, true, lockmode, context);
        relation_close(childrel, NoLock);
    }
}
 
 
/*
 * find_composite_type_dependencies
 *
 * Check to see if the type "typeOid" is being used as a column in some table
 * (possibly nested several levels deep in composite types, arrays, etc!).
 * Eventually, we'd like to propagate the check or rewrite operation
 * into such tables, but for now, just error out if we find any.
 *
 * Caller should provide either the associated relation of a rowtype,
 * or a type name (not both) for use in the error message, if any.
 *
 * Note that "typeOid" is not necessarily a composite type; it could also be
 * another container type such as an array or range, or a domain over one of
 * these things.  The name of this function is therefore somewhat historical,
 * but it's not worth changing.
 *
 * We assume that functions and views depending on the type are not reasons
 * to reject the ALTER.  (How safe is this really?)
 */
void
find_composite_type_dependencies(Oid typeOid, Relation origRelation,
                                 const char *origTypeName)
{
    Relation    depRel;
    ScanKeyData key[2];
    SysScanDesc depScan;
    HeapTuple   depTup;
 
    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();
 
    /*
     * We scan pg_depend to find those things that depend on the given type.
     * (We assume we can ignore refobjsubid for a type.)
     */
    depRel = table_open(DependRelationId, AccessShareLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_depend_refclassid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(TypeRelationId));
    ScanKeyInit(&key[1],
                Anum_pg_depend_refobjid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(typeOid));
 
    depScan = systable_beginscan(depRel, DependReferenceIndexId, true,
                                 NULL, 2, key);
 
    while (HeapTupleIsValid(depTup = systable_getnext(depScan)))
    {
        Form_pg_depend pg_depend = (Form_pg_depend) GETSTRUCT(depTup);
        Relation    rel;
        TupleDesc   tupleDesc;
        Form_pg_attribute att;
 
        /* Check for directly dependent types */
        if (pg_depend->classid == TypeRelationId)
        {
            /*
             * This must be an array, domain, or range containing the given
             * type, so recursively check for uses of this type.  Note that
             * any error message will mention the original type not the
             * container; this is intentional.
             */
            find_composite_type_dependencies(pg_depend->objid,
                                             origRelation, origTypeName);
            continue;
        }
 
        /* Else, ignore dependees that aren't relations */
        if (pg_depend->classid != RelationRelationId)
            continue;
 
        rel = relation_open(pg_depend->objid, AccessShareLock);
        tupleDesc = RelationGetDescr(rel);
 
        /*
         * If objsubid identifies a specific column, refer to that in error
         * messages.  Otherwise, search to see if there's a user column of the
         * type.  (We assume system columns are never of interesting types.)
         * The search is needed because an index containing an expression
         * column of the target type will just be recorded as a whole-relation
         * dependency.  If we do not find a column of the type, the dependency
         * must indicate that the type is transiently referenced in an index
         * expression but not stored on disk, which we assume is OK, just as
         * we do for references in views.  (It could also be that the target
         * type is embedded in some container type that is stored in an index
         * column, but the previous recursion should catch such cases.)
         */
        if (pg_depend->objsubid > 0 && pg_depend->objsubid <= tupleDesc->natts)
            att = TupleDescAttr(tupleDesc, pg_depend->objsubid - 1);
        else
        {
            att = NULL;
            for (int attno = 1; attno <= tupleDesc->natts; attno++)
            {
                att = TupleDescAttr(tupleDesc, attno - 1);
                if (att->atttypid == typeOid && !att->attisdropped)
                    break;
                att = NULL;
            }
            if (att == NULL)
            {
                /* No such column, so assume OK */
                relation_close(rel, AccessShareLock);
                continue;
            }
        }
 
        /*
         * We definitely should reject if the relation has storage.  If it's
         * partitioned, then perhaps we don't have to reject: if there are
         * partitions then we'll fail when we find one, else there is no
         * stored data to worry about.  However, it's possible that the type
         * change would affect conclusions about whether the type is sortable
         * or hashable and thus (if it's a partitioning column) break the
         * partitioning rule.  For now, reject for partitioned rels too.
         */
        if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind) ||
            RELKIND_HAS_PARTITIONS(rel->rd_rel->relkind))
        {
            if (origTypeName)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter type \"%s\" because column \"%s.%s\" uses it",
                                origTypeName,
                                RelationGetRelationName(rel),
                                NameStr(att->attname))));
            else if (origRelation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter type \"%s\" because column \"%s.%s\" uses it",
                                RelationGetRelationName(origRelation),
                                RelationGetRelationName(rel),
                                NameStr(att->attname))));
            else if (origRelation->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter foreign table \"%s\" because column \"%s.%s\" uses its row type",
                                RelationGetRelationName(origRelation),
                                RelationGetRelationName(rel),
                                NameStr(att->attname))));
            else
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter table \"%s\" because column \"%s.%s\" uses its row type",
                                RelationGetRelationName(origRelation),
                                RelationGetRelationName(rel),
                                NameStr(att->attname))));
        }
        else if (OidIsValid(rel->rd_rel->reltype))
        {
            /*
             * A view or composite type itself isn't a problem, but we must
             * recursively check for indirect dependencies via its rowtype.
             */
            find_composite_type_dependencies(rel->rd_rel->reltype,
                                             origRelation, origTypeName);
        }
 
        relation_close(rel, AccessShareLock);
    }
 
    systable_endscan(depScan);
 
    relation_close(depRel, AccessShareLock);
}
 
 
/*
 * find_typed_table_dependencies
 *
 * Check to see if a composite type is being used as the type of a
 * typed table.  Abort if any are found and behavior is RESTRICT.
 * Else return the list of tables.
 */
static List *
find_typed_table_dependencies(Oid typeOid, const char *typeName, DropBehavior behavior)
{
    Relation    classRel;
    ScanKeyData key[1];
    TableScanDesc scan;
    HeapTuple   tuple;
    List       *result = NIL;
 
    classRel = table_open(RelationRelationId, AccessShareLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_class_reloftype,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(typeOid));
 
    scan = table_beginscan_catalog(classRel, 1, key);
 
    while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
    {
        Form_pg_class classform = (Form_pg_class) GETSTRUCT(tuple);
 
        if (behavior == DROP_RESTRICT)
            ereport(ERROR,
                    (errcode(ERRCODE_DEPENDENT_OBJECTS_STILL_EXIST),
                     errmsg("cannot alter type \"%s\" because it is the type of a typed table",
                            typeName),
                     errhint("Use ALTER ... CASCADE to alter the typed tables too.")));
        else
            result = lappend_oid(result, classform->oid);
    }
 
    table_endscan(scan);
    table_close(classRel, AccessShareLock);
 
    return result;
}
 
 
/*
 * check_of_type
 *
 * Check whether a type is suitable for CREATE TABLE OF/ALTER TABLE OF.  If it
 * isn't suitable, throw an error.  Currently, we require that the type
 * originated with CREATE TYPE AS.  We could support any row type, but doing so
 * would require handling a number of extra corner cases in the DDL commands.
 * (Also, allowing domain-over-composite would open up a can of worms about
 * whether and how the domain's constraints should apply to derived tables.)
 */
void
check_of_type(HeapTuple typetuple)
{
    Form_pg_type typ = (Form_pg_type) GETSTRUCT(typetuple);
    bool        typeOk = false;
 
    if (typ->typtype == TYPTYPE_COMPOSITE)
    {
        Relation    typeRelation;
 
        Assert(OidIsValid(typ->typrelid));
        typeRelation = relation_open(typ->typrelid, AccessShareLock);
        typeOk = (typeRelation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE);
 
        /*
         * Close the parent rel, but keep our AccessShareLock on it until xact
         * commit.  That will prevent someone else from deleting or ALTERing
         * the type before the typed table creation/conversion commits.
         */
        relation_close(typeRelation, NoLock);
 
        if (!typeOk)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("type %s is the row type of another table",
                            format_type_be(typ->oid)),
                     errdetail("A typed table must use a stand-alone composite type created with CREATE TYPE.")));
    }
    else
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("type %s is not a composite type",
                        format_type_be(typ->oid))));
}
 
 
/*
 * ALTER TABLE ADD COLUMN
 *
 * Adds an additional attribute to a relation making the assumption that
 * CHECK, NOT NULL, and FOREIGN KEY constraints will be removed from the
 * AT_AddColumn AlterTableCmd by parse_utilcmd.c and added as independent
 * AlterTableCmd's.
 *
 * ADD COLUMN cannot use the normal ALTER TABLE recursion mechanism, because we
 * have to decide at runtime whether to recurse or not depending on whether we
 * actually add a column or merely merge with an existing column.  (We can't
 * check this in a static pre-pass because it won't handle multiple inheritance
 * situations correctly.)
 */
static void
ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
                bool is_view, AlterTableCmd *cmd, LOCKMODE lockmode,
                AlterTableUtilityContext *context)
{
    if (rel->rd_rel->reloftype && !recursing)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot add column to typed table")));
 
    if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
        ATTypedTableRecursion(wqueue, rel, cmd, lockmode, context);
 
    if (recurse && !is_view)
        cmd->recurse = true;
}
 
/*
 * Add a column to a table.  The return value is the address of the
 * new column in the parent relation.
 *
 * cmd is pass-by-ref so that we can replace it with the parse-transformed
 * copy (but that happens only after we check for IF NOT EXISTS).
 */
static ObjectAddress
ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
                AlterTableCmd **cmd, bool recurse, bool recursing,
                LOCKMODE lockmode, AlterTablePass cur_pass,
                AlterTableUtilityContext *context)
{
    Oid         myrelid = RelationGetRelid(rel);
    ColumnDef  *colDef = castNode(ColumnDef, (*cmd)->def);
    bool        if_not_exists = (*cmd)->missing_ok;
    Relation    pgclass,
                attrdesc;
    HeapTuple   reltup;
    Form_pg_class relform;
    Form_pg_attribute attribute;
    int         newattnum;
    char        relkind;
    Expr       *defval;
    List       *children;
    ListCell   *child;
    AlterTableCmd *childcmd;
    ObjectAddress address;
    TupleDesc   tupdesc;
 
    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();
 
    /* At top level, permission check was done in ATPrepCmd, else do it */
    if (recursing)
        ATSimplePermissions((*cmd)->subtype, rel,
                            ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
 
    if (rel->rd_rel->relispartition && !recursing)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot add column to a partition")));
 
    attrdesc = table_open(AttributeRelationId, RowExclusiveLock);
 
    /*
     * Are we adding the column to a recursion child?  If so, check whether to
     * merge with an existing definition for the column.  If we do merge, we
     * must not recurse.  Children will already have the column, and recursing
     * into them would mess up attinhcount.
     */
    if (colDef->inhcount > 0)
    {
        HeapTuple   tuple;
 
        /* Does child already have a column by this name? */
        tuple = SearchSysCacheCopyAttName(myrelid, colDef->colname);
        if (HeapTupleIsValid(tuple))
        {
            Form_pg_attribute childatt = (Form_pg_attribute) GETSTRUCT(tuple);
            Oid         ctypeId;
            int32       ctypmod;
            Oid         ccollid;
 
            /* Child column must match on type, typmod, and collation */
            typenameTypeIdAndMod(NULL, colDef->typeName, &ctypeId, &ctypmod);
            if (ctypeId != childatt->atttypid ||
                ctypmod != childatt->atttypmod)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("child table \"%s\" has different type for column \"%s\"",
                                RelationGetRelationName(rel), colDef->colname)));
            ccollid = GetColumnDefCollation(NULL, colDef, ctypeId);
            if (ccollid != childatt->attcollation)
                ereport(ERROR,
                        (errcode(ERRCODE_COLLATION_MISMATCH),
                         errmsg("child table \"%s\" has different collation for column \"%s\"",
                                RelationGetRelationName(rel), colDef->colname),
                         errdetail("\"%s\" versus \"%s\"",
                                   get_collation_name(ccollid),
                                   get_collation_name(childatt->attcollation))));
 
            /* Bump the existing child att's inhcount */
            if (pg_add_s16_overflow(childatt->attinhcount, 1,
                                    &childatt->attinhcount))
                ereport(ERROR,
                        errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                        errmsg("too many inheritance parents"));
            CatalogTupleUpdate(attrdesc, &tuple->t_self, tuple);
 
            heap_freetuple(tuple);
 
            /* Inform the user about the merge */
            ereport(NOTICE,
                    (errmsg("merging definition of column \"%s\" for child \"%s\"",
                            colDef->colname, RelationGetRelationName(rel))));
 
            table_close(attrdesc, RowExclusiveLock);
 
            /* Make the child column change visible */
            CommandCounterIncrement();
 
            return InvalidObjectAddress;
        }
    }
 
    /* skip if the name already exists and if_not_exists is true */
    if (!check_for_column_name_collision(rel, colDef->colname, if_not_exists))
    {
        table_close(attrdesc, RowExclusiveLock);
        return InvalidObjectAddress;
    }
 
    /*
     * Okay, we need to add the column, so go ahead and do parse
     * transformation.  This can result in queueing up, or even immediately
     * executing, subsidiary operations (such as creation of unique indexes);
     * so we mustn't do it until we have made the if_not_exists check.
     *
     * When recursing, the command was already transformed and we needn't do
     * so again.  Also, if context isn't given we can't transform.  (That
     * currently happens only for AT_AddColumnToView; we expect that view.c
     * passed us a ColumnDef that doesn't need work.)
     */
    if (context != NULL && !recursing)
    {
        *cmd = ATParseTransformCmd(wqueue, tab, rel, *cmd, recurse, lockmode,
                                   cur_pass, context);
        Assert(*cmd != NULL);
        colDef = castNode(ColumnDef, (*cmd)->def);
    }
 
    /*
     * Regular inheritance children are independent enough not to inherit the
     * identity column from parent hence cannot recursively add identity
     * column if the table has inheritance children.
     *
     * Partitions, on the other hand, are integral part of a partitioned table
     * and inherit identity column.  Hence propagate identity column down the
     * partition hierarchy.
     */
    if (colDef->identity &&
        recurse &&
        rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE &&
        find_inheritance_children(myrelid, NoLock) != NIL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot recursively add identity column to table that has child tables")));
 
    pgclass = table_open(RelationRelationId, RowExclusiveLock);
 
    reltup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(myrelid));
    if (!HeapTupleIsValid(reltup))
        elog(ERROR, "cache lookup failed for relation %u", myrelid);
    relform = (Form_pg_class) GETSTRUCT(reltup);
    relkind = relform->relkind;
 
    /* Determine the new attribute's number */
    newattnum = relform->relnatts + 1;
    if (newattnum > MaxHeapAttributeNumber)
        ereport(ERROR,
                (errcode(ERRCODE_TOO_MANY_COLUMNS),
                 errmsg("tables can have at most %d columns",
                        MaxHeapAttributeNumber)));
 
    /*
     * Construct new attribute's pg_attribute entry.
     */
    tupdesc = BuildDescForRelation(list_make1(colDef));
 
    attribute = TupleDescAttr(tupdesc, 0);
 
    /* Fix up attribute number */
    attribute->attnum = newattnum;
 
    /* make sure datatype is legal for a column */
    CheckAttributeType(NameStr(attribute->attname), attribute->atttypid, attribute->attcollation,
                       list_make1_oid(rel->rd_rel->reltype),
                       0);
 
    InsertPgAttributeTuples(attrdesc, tupdesc, myrelid, NULL, NULL);
 
    table_close(attrdesc, RowExclusiveLock);
 
    /*
     * Update pg_class tuple as appropriate
     */
    relform->relnatts = newattnum;
 
    CatalogTupleUpdate(pgclass, &reltup->t_self, reltup);
 
    heap_freetuple(reltup);
 
    /* Post creation hook for new attribute */
    InvokeObjectPostCreateHook(RelationRelationId, myrelid, newattnum);
 
    table_close(pgclass, RowExclusiveLock);
 
    /* Make the attribute's catalog entry visible */
    CommandCounterIncrement();
 
    /*
     * Store the DEFAULT, if any, in the catalogs
     */
    if (colDef->raw_default)
    {
        RawColumnDefault *rawEnt;
 
        rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
        rawEnt->attnum = attribute->attnum;
        rawEnt->raw_default = copyObject(colDef->raw_default);
 
        /*
         * Attempt to skip a complete table rewrite by storing the specified
         * DEFAULT value outside of the heap.  This may be disabled inside
         * AddRelationNewConstraints if the optimization cannot be applied.
         */
        rawEnt->missingMode = (!colDef->generated);
 
        rawEnt->generated = colDef->generated;
 
        /*
         * This function is intended for CREATE TABLE, so it processes a
         * _list_ of defaults, but we just do one.
         */
        AddRelationNewConstraints(rel, list_make1(rawEnt), NIL,
                                  false, true, false, NULL);
 
        /* Make the additional catalog changes visible */
        CommandCounterIncrement();
 
        /*
         * Did the request for a missing value work? If not we'll have to do a
         * rewrite
         */
        if (!rawEnt->missingMode)
            tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
    }
 
    /*
     * Tell Phase 3 to fill in the default expression, if there is one.
     *
     * If there is no default, Phase 3 doesn't have to do anything, because
     * that effectively means that the default is NULL.  The heap tuple access
     * routines always check for attnum > # of attributes in tuple, and return
     * NULL if so, so without any modification of the tuple data we will get
     * the effect of NULL values in the new column.
     *
     * An exception occurs when the new column is of a domain type: the domain
     * might have a not-null constraint, or a check constraint that indirectly
     * rejects nulls.  If there are any domain constraints then we construct
     * an explicit NULL default value that will be passed through
     * CoerceToDomain processing.  (This is a tad inefficient, since it causes
     * rewriting the table which we really don't have to do, but the present
     * design of domain processing doesn't offer any simple way of checking
     * the constraints more directly.)
     *
     * Note: we use build_column_default, and not just the cooked default
     * returned by AddRelationNewConstraints, so that the right thing happens
     * when a datatype's default applies.
     *
     * Note: it might seem that this should happen at the end of Phase 2, so
     * that the effects of subsequent subcommands can be taken into account.
     * It's intentional that we do it now, though.  The new column should be
     * filled according to what is said in the ADD COLUMN subcommand, so that
     * the effects are the same as if this subcommand had been run by itself
     * and the later subcommands had been issued in new ALTER TABLE commands.
     *
     * We can skip this entirely for relations without storage, since Phase 3
     * is certainly not going to touch them.  System attributes don't have
     * interesting defaults, either.
     */
    if (RELKIND_HAS_STORAGE(relkind))
    {
        /*
         * For an identity column, we can't use build_column_default(),
         * because the sequence ownership isn't set yet.  So do it manually.
         */
        if (colDef->identity)
        {
            NextValueExpr *nve = makeNode(NextValueExpr);
 
            nve->seqid = RangeVarGetRelid(colDef->identitySequence, NoLock, false);
            nve->typeId = attribute->atttypid;
 
            defval = (Expr *) nve;
 
            /* must do a rewrite for identity columns */
            tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
        }
        else
            defval = (Expr *) build_column_default(rel, attribute->attnum);
 
        if (!defval && DomainHasConstraints(attribute->atttypid))
        {
            Oid         baseTypeId;
            int32       baseTypeMod;
            Oid         baseTypeColl;
 
            baseTypeMod = attribute->atttypmod;
            baseTypeId = getBaseTypeAndTypmod(attribute->atttypid, &baseTypeMod);
            baseTypeColl = get_typcollation(baseTypeId);
            defval = (Expr *) makeNullConst(baseTypeId, baseTypeMod, baseTypeColl);
            defval = (Expr *) coerce_to_target_type(NULL,
                                                    (Node *) defval,
                                                    baseTypeId,
                                                    attribute->atttypid,
                                                    attribute->atttypmod,
                                                    COERCION_ASSIGNMENT,
                                                    COERCE_IMPLICIT_CAST,
                                                    -1);
            if (defval == NULL) /* should not happen */
                elog(ERROR, "failed to coerce base type to domain");
        }
 
        if (defval)
        {
            NewColumnValue *newval;
 
            newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
            newval->attnum = attribute->attnum;
            newval->expr = expression_planner(defval);
            newval->is_generated = (colDef->generated != '\0');
 
            tab->newvals = lappend(tab->newvals, newval);
        }
 
        if (DomainHasConstraints(attribute->atttypid))
            tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 
        if (!TupleDescAttr(rel->rd_att, attribute->attnum - 1)->atthasmissing)
        {
            /*
             * If the new column is NOT NULL, and there is no missing value,
             * tell Phase 3 it needs to check for NULLs.
             */
            tab->verify_new_notnull |= colDef->is_not_null;
        }
    }
 
    /*
     * Add needed dependency entries for the new column.
     */
    add_column_datatype_dependency(myrelid, newattnum, attribute->atttypid);
    add_column_collation_dependency(myrelid, newattnum, attribute->attcollation);
 
    /*
     * Propagate to children as appropriate.  Unlike most other ALTER
     * routines, we have to do this one level of recursion at a time; we can't
     * use find_all_inheritors to do it in one pass.
     */
    children =
        find_inheritance_children(RelationGetRelid(rel), lockmode);
 
    /*
     * If we are told not to recurse, there had better not be any child
     * tables; else the addition would put them out of step.
     */
    if (children && !recurse)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("column must be added to child tables too")));
 
    /* Children should see column as singly inherited */
    if (!recursing)
    {
        childcmd = copyObject(*cmd);
        colDef = castNode(ColumnDef, childcmd->def);
        colDef->inhcount = 1;
        colDef->is_local = false;
    }
    else
        childcmd = *cmd;        /* no need to copy again */
 
    foreach(child, children)
    {
        Oid         childrelid = lfirst_oid(child);
        Relation    childrel;
        AlteredTableInfo *childtab;
 
        /* find_inheritance_children already got lock */
        childrel = table_open(childrelid, NoLock);
        CheckAlterTableIsSafe(childrel);
 
        /* Find or create work queue entry for this table */
        childtab = ATGetQueueEntry(wqueue, childrel);
 
        /* Recurse to child; return value is ignored */
        ATExecAddColumn(wqueue, childtab, childrel,
                        &childcmd, recurse, true,
                        lockmode, cur_pass, context);
 
        table_close(childrel, NoLock);
    }
 
    ObjectAddressSubSet(address, RelationRelationId, myrelid, newattnum);
    return address;
}
 
/*
 * If a new or renamed column will collide with the name of an existing
 * column and if_not_exists is false then error out, else do nothing.
 */
static bool
check_for_column_name_collision(Relation rel, const char *colname,
                                bool if_not_exists)
{
    HeapTuple   attTuple;
    int         attnum;
 
    /*
     * this test is deliberately not attisdropped-aware, since if one tries to
     * add a column matching a dropped column name, it's gonna fail anyway.
     */
    attTuple = SearchSysCache2(ATTNAME,
                               ObjectIdGetDatum(RelationGetRelid(rel)),
                               PointerGetDatum(colname));
    if (!HeapTupleIsValid(attTuple))
        return true;
 
    attnum = ((Form_pg_attribute) GETSTRUCT(attTuple))->attnum;
    ReleaseSysCache(attTuple);
 
    /*
     * We throw a different error message for conflicts with system column
     * names, since they are normally not shown and the user might otherwise
     * be confused about the reason for the conflict.
     */
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_COLUMN),
                 errmsg("column name \"%s\" conflicts with a system column name",
                        colname)));
    else
    {
        if (if_not_exists)
        {
            ereport(NOTICE,
                    (errcode(ERRCODE_DUPLICATE_COLUMN),
                     errmsg("column \"%s\" of relation \"%s\" already exists, skipping",
                            colname, RelationGetRelationName(rel))));
            return false;
        }
 
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" already exists",
                        colname, RelationGetRelationName(rel))));
    }
 
    return true;
}
 
/*
 * Install a column's dependency on its datatype.
 */
static void
add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid)
{
    ObjectAddress myself,
                referenced;
 
    myself.classId = RelationRelationId;
    myself.objectId = relid;
    myself.objectSubId = attnum;
    referenced.classId = TypeRelationId;
    referenced.objectId = typid;
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
}
 
/*
 * Install a column's dependency on its collation.
 */
static void
add_column_collation_dependency(Oid relid, int32 attnum, Oid collid)
{
    ObjectAddress myself,
                referenced;
 
    /* We know the default collation is pinned, so don't bother recording it */
    if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID)
    {
        myself.classId = RelationRelationId;
        myself.objectId = relid;
        myself.objectSubId = attnum;
        referenced.classId = CollationRelationId;
        referenced.objectId = collid;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }
}
 
/*
 * ALTER TABLE ALTER COLUMN DROP NOT NULL
 *
 * Return the address of the modified column.  If the column was already
 * nullable, InvalidObjectAddress is returned.
 */
static ObjectAddress
ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
{
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    Relation    attr_rel;
    List       *indexoidlist;
    ObjectAddress address;
 
    /*
     * lookup the attribute
     */
    attr_rel = table_open(AttributeRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    /* Prevent them from altering a system attribute */
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    if (attTup->attidentity)
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("column \"%s\" of relation \"%s\" is an identity column",
                        colName, RelationGetRelationName(rel))));
 
    /*
     * Check that the attribute is not in a primary key or in an index used as
     * a replica identity.
     *
     * Note: we'll throw error even if the pkey index is not valid.
     */
 
    /* Loop over all indexes on the relation */
    indexoidlist = RelationGetIndexList(rel);
 
    foreach_oid(indexoid, indexoidlist)
    {
        HeapTuple   indexTuple;
        Form_pg_index indexStruct;
 
        indexTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexoid));
        if (!HeapTupleIsValid(indexTuple))
            elog(ERROR, "cache lookup failed for index %u", indexoid);
        indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);
 
        /*
         * If the index is not a primary key or an index used as replica
         * identity, skip the check.
         */
        if (indexStruct->indisprimary || indexStruct->indisreplident)
        {
            /*
             * Loop over each attribute in the primary key or the index used
             * as replica identity and see if it matches the to-be-altered
             * attribute.
             */
            for (int i = 0; i < indexStruct->indnkeyatts; i++)
            {
                if (indexStruct->indkey.values[i] == attnum)
                {
                    if (indexStruct->indisprimary)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                                 errmsg("column \"%s\" is in a primary key",
                                        colName)));
                    else
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                                 errmsg("column \"%s\" is in index used as replica identity",
                                        colName)));
                }
            }
        }
 
        ReleaseSysCache(indexTuple);
    }
 
    list_free(indexoidlist);
 
    /* If rel is partition, shouldn't drop NOT NULL if parent has the same */
    if (rel->rd_rel->relispartition)
    {
        Oid         parentId = get_partition_parent(RelationGetRelid(rel), false);
        Relation    parent = table_open(parentId, AccessShareLock);
        TupleDesc   tupDesc = RelationGetDescr(parent);
        AttrNumber  parent_attnum;
 
        parent_attnum = get_attnum(parentId, colName);
        if (TupleDescAttr(tupDesc, parent_attnum - 1)->attnotnull)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("column \"%s\" is marked NOT NULL in parent table",
                            colName)));
        table_close(parent, AccessShareLock);
    }
 
    /*
     * Okay, actually perform the catalog change ... if needed
     */
    if (attTup->attnotnull)
    {
        attTup->attnotnull = false;
 
        CatalogTupleUpdate(attr_rel, &tuple->t_self, tuple);
 
        ObjectAddressSubSet(address, RelationRelationId,
                            RelationGetRelid(rel), attnum);
    }
    else
        address = InvalidObjectAddress;
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), attnum);
 
    table_close(attr_rel, RowExclusiveLock);
 
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN SET NOT NULL
 */
 
static void
ATPrepSetNotNull(List **wqueue, Relation rel,
                 AlterTableCmd *cmd, bool recurse, bool recursing,
                 LOCKMODE lockmode, AlterTableUtilityContext *context)
{
    /*
     * If we're already recursing, there's nothing to do; the topmost
     * invocation of ATSimpleRecursion already visited all children.
     */
    if (recursing)
        return;
 
    /*
     * If the target column is already marked NOT NULL, we can skip recursing
     * to children, because their columns should already be marked NOT NULL as
     * well.  But there's no point in checking here unless the relation has
     * some children; else we can just wait till execution to check.  (If it
     * does have children, however, this can save taking per-child locks
     * unnecessarily.  This greatly improves concurrency in some parallel
     * restore scenarios.)
     *
     * Unfortunately, we can only apply this optimization to partitioned
     * tables, because traditional inheritance doesn't enforce that child
     * columns be NOT NULL when their parent is.  (That's a bug that should
     * get fixed someday.)
     */
    if (rel->rd_rel->relhassubclass &&
        rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        HeapTuple   tuple;
        bool        attnotnull;
 
        tuple = SearchSysCacheAttName(RelationGetRelid(rel), cmd->name);
 
        /* Might as well throw the error now, if name is bad */
        if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" of relation \"%s\" does not exist",
                            cmd->name, RelationGetRelationName(rel))));
 
        attnotnull = ((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull;
        ReleaseSysCache(tuple);
        if (attnotnull)
            return;
    }
 
    /*
     * If we have ALTER TABLE ONLY ... SET NOT NULL on a partitioned table,
     * apply ALTER TABLE ... CHECK NOT NULL to every child.  Otherwise, use
     * normal recursion logic.
     */
    if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
        !recurse)
    {
        AlterTableCmd *newcmd = makeNode(AlterTableCmd);
 
        newcmd->subtype = AT_CheckNotNull;
        newcmd->name = pstrdup(cmd->name);
        ATSimpleRecursion(wqueue, rel, newcmd, true, lockmode, context);
    }
    else
        ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
}
 
/*
 * Return the address of the modified column.  If the column was already NOT
 * NULL, InvalidObjectAddress is returned.
 */
static ObjectAddress
ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
                 const char *colName, LOCKMODE lockmode)
{
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    Relation    attr_rel;
    ObjectAddress address;
 
    /*
     * lookup the attribute
     */
    attr_rel = table_open(AttributeRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
 
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
 
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    /* Prevent them from altering a system attribute */
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    /*
     * Okay, actually perform the catalog change ... if needed
     */
    if (!attTup->attnotnull)
    {
        attTup->attnotnull = true;
 
        CatalogTupleUpdate(attr_rel, &tuple->t_self, tuple);
 
        /*
         * Ordinarily phase 3 must ensure that no NULLs exist in columns that
         * are set NOT NULL; however, if we can find a constraint which proves
         * this then we can skip that.  We needn't bother looking if we've
         * already found that we must verify some other not-null constraint.
         */
        if (!tab->verify_new_notnull && !NotNullImpliedByRelConstraints(rel, attTup))
        {
            /* Tell Phase 3 it needs to test the constraint */
            tab->verify_new_notnull = true;
        }
 
        ObjectAddressSubSet(address, RelationRelationId,
                            RelationGetRelid(rel), attnum);
    }
    else
        address = InvalidObjectAddress;
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), attnum);
 
    table_close(attr_rel, RowExclusiveLock);
 
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN CHECK NOT NULL
 *
 * This doesn't exist in the grammar, but we generate AT_CheckNotNull
 * commands against the partitions of a partitioned table if the user
 * writes ALTER TABLE ONLY ... SET NOT NULL on the partitioned table,
 * or tries to create a primary key on it (which internally creates
 * AT_SetNotNull on the partitioned table).   Such a command doesn't
 * allow us to actually modify any partition, but we want to let it
 * go through if the partitions are already properly marked.
 *
 * In future, this might need to adjust the child table's state, likely
 * by incrementing an inheritance count for the attnotnull constraint.
 * For now we need only check for the presence of the flag.
 */
static void
ATExecCheckNotNull(AlteredTableInfo *tab, Relation rel,
                   const char *colName, LOCKMODE lockmode)
{
    HeapTuple   tuple;
 
    tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
 
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                errcode(ERRCODE_UNDEFINED_COLUMN),
                errmsg("column \"%s\" of relation \"%s\" does not exist",
                       colName, RelationGetRelationName(rel)));
 
    if (!((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("constraint must be added to child tables too"),
                 errdetail("Column \"%s\" of relation \"%s\" is not already NOT NULL.",
                           colName, RelationGetRelationName(rel)),
                 errhint("Do not specify the ONLY keyword.")));
 
    ReleaseSysCache(tuple);
}
 
/*
 * NotNullImpliedByRelConstraints
 *      Does rel's existing constraints imply NOT NULL for the given attribute?
 */
static bool
NotNullImpliedByRelConstraints(Relation rel, Form_pg_attribute attr)
{
    NullTest   *nnulltest = makeNode(NullTest);
 
    nnulltest->arg = (Expr *) makeVar(1,
                                      attr->attnum,
                                      attr->atttypid,
                                      attr->atttypmod,
                                      attr->attcollation,
                                      0);
    nnulltest->nulltesttype = IS_NOT_NULL;
 
    /*
     * argisrow = false is correct even for a composite column, because
     * attnotnull does not represent a SQL-spec IS NOT NULL test in such a
     * case, just IS DISTINCT FROM NULL.
     */
    nnulltest->argisrow = false;
    nnulltest->location = -1;
 
    if (ConstraintImpliedByRelConstraint(rel, list_make1(nnulltest), NIL))
    {
        ereport(DEBUG1,
                (errmsg_internal("existing constraints on column \"%s.%s\" are sufficient to prove that it does not contain nulls",
                                 RelationGetRelationName(rel), NameStr(attr->attname))));
        return true;
    }
 
    return false;
}
 
/*
 * ALTER TABLE ALTER COLUMN SET/DROP DEFAULT
 *
 * Return the address of the affected column.
 */
static ObjectAddress
ATExecColumnDefault(Relation rel, const char *colName,
                    Node *newDefault, LOCKMODE lockmode)
{
    TupleDesc   tupdesc = RelationGetDescr(rel);
    AttrNumber  attnum;
    ObjectAddress address;
 
    /*
     * get the number of the attribute
     */
    attnum = get_attnum(RelationGetRelid(rel), colName);
    if (attnum == InvalidAttrNumber)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
 
    /* Prevent them from altering a system attribute */
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    if (TupleDescAttr(tupdesc, attnum - 1)->attidentity)
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("column \"%s\" of relation \"%s\" is an identity column",
                        colName, RelationGetRelationName(rel)),
        /* translator: %s is an SQL ALTER command */
                 newDefault ? 0 : errhint("Use %s instead.",
                                          "ALTER TABLE ... ALTER COLUMN ... DROP IDENTITY")));
 
    if (TupleDescAttr(tupdesc, attnum - 1)->attgenerated)
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("column \"%s\" of relation \"%s\" is a generated column",
                        colName, RelationGetRelationName(rel)),
                 newDefault ?
        /* translator: %s is an SQL ALTER command */
                 errhint("Use %s instead.", "ALTER TABLE ... ALTER COLUMN ... SET EXPRESSION") :
                 (TupleDescAttr(tupdesc, attnum - 1)->attgenerated == ATTRIBUTE_GENERATED_STORED ?
                  errhint("Use %s instead.", "ALTER TABLE ... ALTER COLUMN ... DROP EXPRESSION") : 0)));
 
    /*
     * Remove any old default for the column.  We use RESTRICT here for
     * safety, but at present we do not expect anything to depend on the
     * default.
     *
     * We treat removing the existing default as an internal operation when it
     * is preparatory to adding a new default, but as a user-initiated
     * operation when the user asked for a drop.
     */
    RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false,
                      newDefault != NULL);
 
    if (newDefault)
    {
        /* SET DEFAULT */
        RawColumnDefault *rawEnt;
 
        rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
        rawEnt->attnum = attnum;
        rawEnt->raw_default = newDefault;
        rawEnt->missingMode = false;
        rawEnt->generated = '\0';
 
        /*
         * This function is intended for CREATE TABLE, so it processes a
         * _list_ of defaults, but we just do one.
         */
        AddRelationNewConstraints(rel, list_make1(rawEnt), NIL,
                                  false, true, false, NULL);
    }
 
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    return address;
}
 
/*
 * Add a pre-cooked default expression.
 *
 * Return the address of the affected column.
 */
static ObjectAddress
ATExecCookedColumnDefault(Relation rel, AttrNumber attnum,
                          Node *newDefault)
{
    ObjectAddress address;
 
    /* We assume no checking is required */
 
    /*
     * Remove any old default for the column.  We use RESTRICT here for
     * safety, but at present we do not expect anything to depend on the
     * default.  (In ordinary cases, there could not be a default in place
     * anyway, but it's possible when combining LIKE with inheritance.)
     */
    RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false,
                      true);
 
    (void) StoreAttrDefault(rel, attnum, newDefault, true, false);
 
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN ADD IDENTITY
 *
 * Return the address of the affected column.
 */
static ObjectAddress
ATExecAddIdentity(Relation rel, const char *colName,
                  Node *def, LOCKMODE lockmode, bool recurse, bool recursing)
{
    Relation    attrelation;
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    ObjectAddress address;
    ColumnDef  *cdef = castNode(ColumnDef, def);
    bool        ispartitioned;
 
    ispartitioned = (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
    if (ispartitioned && !recurse)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot add identity to a column of only the partitioned table"),
                 errhint("Do not specify the ONLY keyword.")));
 
    if (rel->rd_rel->relispartition && !recursing)
        ereport(ERROR,
                errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                errmsg("cannot add identity to a column of a partition"));
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    /* Can't alter a system attribute */
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    /*
     * Creating a column as identity implies NOT NULL, so adding the identity
     * to an existing column that is not NOT NULL would create a state that
     * cannot be reproduced without contortions.
     */
    if (!attTup->attnotnull)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
                        colName, RelationGetRelationName(rel))));
 
    if (attTup->attidentity)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("column \"%s\" of relation \"%s\" is already an identity column",
                        colName, RelationGetRelationName(rel))));
 
    if (attTup->atthasdef)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("column \"%s\" of relation \"%s\" already has a default value",
                        colName, RelationGetRelationName(rel))));
 
    attTup->attidentity = cdef->identity;
    CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              attTup->attnum);
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    heap_freetuple(tuple);
 
    table_close(attrelation, RowExclusiveLock);
 
    /*
     * Recurse to propagate the identity column to partitions.  Identity is
     * not inherited in regular inheritance children.
     */
    if (recurse && ispartitioned)
    {
        List       *children;
        ListCell   *lc;
 
        children = find_inheritance_children(RelationGetRelid(rel), lockmode);
 
        foreach(lc, children)
        {
            Relation    childrel;
 
            childrel = table_open(lfirst_oid(lc), NoLock);
            ATExecAddIdentity(childrel, colName, def, lockmode, recurse, true);
            table_close(childrel, NoLock);
        }
    }
 
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN SET { GENERATED or sequence options }
 *
 * Return the address of the affected column.
 */
static ObjectAddress
ATExecSetIdentity(Relation rel, const char *colName, Node *def,
                  LOCKMODE lockmode, bool recurse, bool recursing)
{
    ListCell   *option;
    DefElem    *generatedEl = NULL;
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    Relation    attrelation;
    ObjectAddress address;
    bool        ispartitioned;
 
    ispartitioned = (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
    if (ispartitioned && !recurse)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot change identity column of only the partitioned table"),
                 errhint("Do not specify the ONLY keyword.")));
 
    if (rel->rd_rel->relispartition && !recursing)
        ereport(ERROR,
                errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                errmsg("cannot change identity column of a partition"));
 
    foreach(option, castNode(List, def))
    {
        DefElem    *defel = lfirst_node(DefElem, option);
 
        if (strcmp(defel->defname, "generated") == 0)
        {
            if (generatedEl)
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                         errmsg("conflicting or redundant options")));
            generatedEl = defel;
        }
        else
            elog(ERROR, "option \"%s\" not recognized",
                 defel->defname);
    }
 
    /*
     * Even if there is nothing to change here, we run all the checks.  There
     * will be a subsequent ALTER SEQUENCE that relies on everything being
     * there.
     */
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
 
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    if (!attTup->attidentity)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
                        colName, RelationGetRelationName(rel))));
 
    if (generatedEl)
    {
        attTup->attidentity = defGetInt32(generatedEl);
        CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
 
        InvokeObjectPostAlterHook(RelationRelationId,
                                  RelationGetRelid(rel),
                                  attTup->attnum);
        ObjectAddressSubSet(address, RelationRelationId,
                            RelationGetRelid(rel), attnum);
    }
    else
        address = InvalidObjectAddress;
 
    heap_freetuple(tuple);
    table_close(attrelation, RowExclusiveLock);
 
    /*
     * Recurse to propagate the identity change to partitions. Identity is not
     * inherited in regular inheritance children.
     */
    if (generatedEl && recurse && ispartitioned)
    {
        List       *children;
        ListCell   *lc;
 
        children = find_inheritance_children(RelationGetRelid(rel), lockmode);
 
        foreach(lc, children)
        {
            Relation    childrel;
 
            childrel = table_open(lfirst_oid(lc), NoLock);
            ATExecSetIdentity(childrel, colName, def, lockmode, recurse, true);
            table_close(childrel, NoLock);
        }
    }
 
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN DROP IDENTITY
 *
 * Return the address of the affected column.
 */
static ObjectAddress
ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode,
                   bool recurse, bool recursing)
{
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    Relation    attrelation;
    ObjectAddress address;
    Oid         seqid;
    ObjectAddress seqaddress;
    bool        ispartitioned;
 
    ispartitioned = (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
    if (ispartitioned && !recurse)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot drop identity from a column of only the partitioned table"),
                 errhint("Do not specify the ONLY keyword.")));
 
    if (rel->rd_rel->relispartition && !recursing)
        ereport(ERROR,
                errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                errmsg("cannot drop identity from a column of a partition"));
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
 
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    if (!attTup->attidentity)
    {
        if (!missing_ok)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("column \"%s\" of relation \"%s\" is not an identity column",
                            colName, RelationGetRelationName(rel))));
        else
        {
            ereport(NOTICE,
                    (errmsg("column \"%s\" of relation \"%s\" is not an identity column, skipping",
                            colName, RelationGetRelationName(rel))));
            heap_freetuple(tuple);
            table_close(attrelation, RowExclusiveLock);
            return InvalidObjectAddress;
        }
    }
 
    attTup->attidentity = '\0';
    CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              attTup->attnum);
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    heap_freetuple(tuple);
 
    table_close(attrelation, RowExclusiveLock);
 
    /*
     * Recurse to drop the identity from column in partitions.  Identity is
     * not inherited in regular inheritance children so ignore them.
     */
    if (recurse && ispartitioned)
    {
        List       *children;
        ListCell   *lc;
 
        children = find_inheritance_children(RelationGetRelid(rel), lockmode);
 
        foreach(lc, children)
        {
            Relation    childrel;
 
            childrel = table_open(lfirst_oid(lc), NoLock);
            ATExecDropIdentity(childrel, colName, false, lockmode, recurse, true);
            table_close(childrel, NoLock);
        }
    }
 
    if (!recursing)
    {
        /* drop the internal sequence */
        seqid = getIdentitySequence(rel, attnum, false);
        deleteDependencyRecordsForClass(RelationRelationId, seqid,
                                        RelationRelationId, DEPENDENCY_INTERNAL);
        CommandCounterIncrement();
        seqaddress.classId = RelationRelationId;
        seqaddress.objectId = seqid;
        seqaddress.objectSubId = 0;
        performDeletion(&seqaddress, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
    }
 
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN SET EXPRESSION
 *
 * Return the address of the affected column.
 */
static ObjectAddress
ATExecSetExpression(AlteredTableInfo *tab, Relation rel, const char *colName,
                    Node *newExpr, LOCKMODE lockmode)
{
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    Oid         attrdefoid;
    ObjectAddress address;
    Expr       *defval;
    NewColumnValue *newval;
    RawColumnDefault *rawEnt;
 
    tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
 
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    if (attTup->attgenerated != ATTRIBUTE_GENERATED_STORED)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("column \"%s\" of relation \"%s\" is not a generated column",
                        colName, RelationGetRelationName(rel))));
    ReleaseSysCache(tuple);
 
    /*
     * Clear all the missing values if we're rewriting the table, since this
     * renders them pointless.
     */
    RelationClearMissing(rel);
 
    /* make sure we don't conflict with later attribute modifications */
    CommandCounterIncrement();
 
    /*
     * Find everything that depends on the column (constraints, indexes, etc),
     * and record enough information to let us recreate the objects after
     * rewrite.
     */
    RememberAllDependentForRebuilding(tab, AT_SetExpression, rel, attnum, colName);
 
    /*
     * Drop the dependency records of the GENERATED expression, in particular
     * its INTERNAL dependency on the column, which would otherwise cause
     * dependency.c to refuse to perform the deletion.
     */
    attrdefoid = GetAttrDefaultOid(RelationGetRelid(rel), attnum);
    if (!OidIsValid(attrdefoid))
        elog(ERROR, "could not find attrdef tuple for relation %u attnum %d",
             RelationGetRelid(rel), attnum);
    (void) deleteDependencyRecordsFor(AttrDefaultRelationId, attrdefoid, false);
 
    /* Make above changes visible */
    CommandCounterIncrement();
 
    /*
     * Get rid of the GENERATED expression itself.  We use RESTRICT here for
     * safety, but at present we do not expect anything to depend on the
     * expression.
     */
    RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT,
                      false, false);
 
    /* Prepare to store the new expression, in the catalogs */
    rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
    rawEnt->attnum = attnum;
    rawEnt->raw_default = newExpr;
    rawEnt->missingMode = false;
    rawEnt->generated = ATTRIBUTE_GENERATED_STORED;
 
    /* Store the generated expression */
    AddRelationNewConstraints(rel, list_make1(rawEnt), NIL,
                              false, true, false, NULL);
 
    /* Make above new expression visible */
    CommandCounterIncrement();
 
    /* Prepare for table rewrite */
    defval = (Expr *) build_column_default(rel, attnum);
 
    newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
    newval->attnum = attnum;
    newval->expr = expression_planner(defval);
    newval->is_generated = true;
 
    tab->newvals = lappend(tab->newvals, newval);
    tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 
    /* Drop any pg_statistic entry for the column */
    RemoveStatistics(RelationGetRelid(rel), attnum);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), attnum);
 
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN DROP EXPRESSION
 */
static void
ATPrepDropExpression(Relation rel, AlterTableCmd *cmd, bool recurse, bool recursing, LOCKMODE lockmode)
{
    /*
     * Reject ONLY if there are child tables.  We could implement this, but it
     * is a bit complicated.  GENERATED clauses must be attached to the column
     * definition and cannot be added later like DEFAULT, so if a child table
     * has a generation expression that the parent does not have, the child
     * column will necessarily be an attislocal column.  So to implement ONLY
     * here, we'd need extra code to update attislocal of the direct child
     * tables, somewhat similar to how DROP COLUMN does it, so that the
     * resulting state can be properly dumped and restored.
     */
    if (!recurse &&
        find_inheritance_children(RelationGetRelid(rel), lockmode))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("ALTER TABLE / DROP EXPRESSION must be applied to child tables too")));
 
    /*
     * Cannot drop generation expression from inherited columns.
     */
    if (!recursing)
    {
        HeapTuple   tuple;
        Form_pg_attribute attTup;
 
        tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), cmd->name);
        if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" of relation \"%s\" does not exist",
                            cmd->name, RelationGetRelationName(rel))));
 
        attTup = (Form_pg_attribute) GETSTRUCT(tuple);
 
        if (attTup->attinhcount > 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("cannot drop generation expression from inherited column")));
    }
}
 
/*
 * Return the address of the affected column.
 */
static ObjectAddress
ATExecDropExpression(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode)
{
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    Relation    attrelation;
    Oid         attrdefoid;
    ObjectAddress address;
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
 
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    if (attTup->attgenerated != ATTRIBUTE_GENERATED_STORED)
    {
        if (!missing_ok)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("column \"%s\" of relation \"%s\" is not a stored generated column",
                            colName, RelationGetRelationName(rel))));
        else
        {
            ereport(NOTICE,
                    (errmsg("column \"%s\" of relation \"%s\" is not a stored generated column, skipping",
                            colName, RelationGetRelationName(rel))));
            heap_freetuple(tuple);
            table_close(attrelation, RowExclusiveLock);
            return InvalidObjectAddress;
        }
    }
 
    /*
     * Mark the column as no longer generated.  (The atthasdef flag needs to
     * get cleared too, but RemoveAttrDefault will handle that.)
     */
    attTup->attgenerated = '\0';
    CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              attnum);
    heap_freetuple(tuple);
 
    table_close(attrelation, RowExclusiveLock);
 
    /*
     * Drop the dependency records of the GENERATED expression, in particular
     * its INTERNAL dependency on the column, which would otherwise cause
     * dependency.c to refuse to perform the deletion.
     */
    attrdefoid = GetAttrDefaultOid(RelationGetRelid(rel), attnum);
    if (!OidIsValid(attrdefoid))
        elog(ERROR, "could not find attrdef tuple for relation %u attnum %d",
             RelationGetRelid(rel), attnum);
    (void) deleteDependencyRecordsFor(AttrDefaultRelationId, attrdefoid, false);
 
    /* Make above changes visible */
    CommandCounterIncrement();
 
    /*
     * Get rid of the GENERATED expression itself.  We use RESTRICT here for
     * safety, but at present we do not expect anything to depend on the
     * default.
     */
    RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT,
                      false, false);
 
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    return address;
}
 
/*
 * ALTER TABLE ALTER COLUMN SET STATISTICS
 *
 * Return value is the address of the modified column
 */
static ObjectAddress
ATExecSetStatistics(Relation rel, const char *colName, int16 colNum, Node *newValue, LOCKMODE lockmode)
{
    int         newtarget = 0;
    bool        newtarget_default;
    Relation    attrelation;
    HeapTuple   tuple,
                newtuple;
    Form_pg_attribute attrtuple;
    AttrNumber  attnum;
    ObjectAddress address;
    Datum       repl_val[Natts_pg_attribute];
    bool        repl_null[Natts_pg_attribute];
    bool        repl_repl[Natts_pg_attribute];
 
    /*
     * We allow referencing columns by numbers only for indexes, since table
     * column numbers could contain gaps if columns are later dropped.
     */
    if (rel->rd_rel->relkind != RELKIND_INDEX &&
        rel->rd_rel->relkind != RELKIND_PARTITIONED_INDEX &&
        !colName)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot refer to non-index column by number")));
 
    /* -1 was used in previous versions for the default setting */
    if (newValue && intVal(newValue) != -1)
    {
        newtarget = intVal(newValue);
        newtarget_default = false;
    }
    else
        newtarget_default = true;
 
    if (!newtarget_default)
    {
        /*
         * Limit target to a sane range
         */
        if (newtarget < 0)
        {
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("statistics target %d is too low",
                            newtarget)));
        }
        else if (newtarget > MAX_STATISTICS_TARGET)
        {
            newtarget = MAX_STATISTICS_TARGET;
            ereport(WARNING,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("lowering statistics target to %d",
                            newtarget)));
        }
    }
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
 
    if (colName)
    {
        tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
 
        if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" of relation \"%s\" does not exist",
                            colName, RelationGetRelationName(rel))));
    }
    else
    {
        tuple = SearchSysCacheAttNum(RelationGetRelid(rel), colNum);
 
        if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column number %d of relation \"%s\" does not exist",
                            colNum, RelationGetRelationName(rel))));
    }
 
    attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
 
    attnum = attrtuple->attnum;
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    if (rel->rd_rel->relkind == RELKIND_INDEX ||
        rel->rd_rel->relkind == RELKIND_PARTITIONED_INDEX)
    {
        if (attnum > rel->rd_index->indnkeyatts)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot alter statistics on included column \"%s\" of index \"%s\"",
                            NameStr(attrtuple->attname), RelationGetRelationName(rel))));
        else if (rel->rd_index->indkey.values[attnum - 1] != 0)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot alter statistics on non-expression column \"%s\" of index \"%s\"",
                            NameStr(attrtuple->attname), RelationGetRelationName(rel)),
                     errhint("Alter statistics on table column instead.")));
    }
 
    /* Build new tuple. */
    memset(repl_null, false, sizeof(repl_null));
    memset(repl_repl, false, sizeof(repl_repl));
    if (!newtarget_default)
        repl_val[Anum_pg_attribute_attstattarget - 1] = newtarget;
    else
        repl_null[Anum_pg_attribute_attstattarget - 1] = true;
    repl_repl[Anum_pg_attribute_attstattarget - 1] = true;
    newtuple = heap_modify_tuple(tuple, RelationGetDescr(attrelation),
                                 repl_val, repl_null, repl_repl);
    CatalogTupleUpdate(attrelation, &tuple->t_self, newtuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              attrtuple->attnum);
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
 
    heap_freetuple(newtuple);
 
    ReleaseSysCache(tuple);
 
    table_close(attrelation, RowExclusiveLock);
 
    return address;
}
 
/*
 * Return value is the address of the modified column
 */
static ObjectAddress
ATExecSetOptions(Relation rel, const char *colName, Node *options,
                 bool isReset, LOCKMODE lockmode)
{
    Relation    attrelation;
    HeapTuple   tuple,
                newtuple;
    Form_pg_attribute attrtuple;
    AttrNumber  attnum;
    Datum       datum,
                newOptions;
    bool        isnull;
    ObjectAddress address;
    Datum       repl_val[Natts_pg_attribute];
    bool        repl_null[Natts_pg_attribute];
    bool        repl_repl[Natts_pg_attribute];
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
 
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
    attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
 
    attnum = attrtuple->attnum;
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    /* Generate new proposed attoptions (text array) */
    datum = SysCacheGetAttr(ATTNAME, tuple, Anum_pg_attribute_attoptions,
                            &isnull);
    newOptions = transformRelOptions(isnull ? (Datum) 0 : datum,
                                     castNode(List, options), NULL, NULL,
                                     false, isReset);
    /* Validate new options */
    (void) attribute_reloptions(newOptions, true);
 
    /* Build new tuple. */
    memset(repl_null, false, sizeof(repl_null));
    memset(repl_repl, false, sizeof(repl_repl));
    if (newOptions != (Datum) 0)
        repl_val[Anum_pg_attribute_attoptions - 1] = newOptions;
    else
        repl_null[Anum_pg_attribute_attoptions - 1] = true;
    repl_repl[Anum_pg_attribute_attoptions - 1] = true;
    newtuple = heap_modify_tuple(tuple, RelationGetDescr(attrelation),
                                 repl_val, repl_null, repl_repl);
 
    /* Update system catalog. */
    CatalogTupleUpdate(attrelation, &newtuple->t_self, newtuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              attrtuple->attnum);
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
 
    heap_freetuple(newtuple);
 
    ReleaseSysCache(tuple);
 
    table_close(attrelation, RowExclusiveLock);
 
    return address;
}
 
/*
 * Helper function for ATExecSetStorage and ATExecSetCompression
 *
 * Set the attstorage and/or attcompression fields for index columns
 * associated with the specified table column.
 */
static void
SetIndexStorageProperties(Relation rel, Relation attrelation,
                          AttrNumber attnum,
                          bool setstorage, char newstorage,
                          bool setcompression, char newcompression,
                          LOCKMODE lockmode)
{
    ListCell   *lc;
 
    foreach(lc, RelationGetIndexList(rel))
    {
        Oid         indexoid = lfirst_oid(lc);
        Relation    indrel;
        AttrNumber  indattnum = 0;
        HeapTuple   tuple;
 
        indrel = index_open(indexoid, lockmode);
 
        for (int i = 0; i < indrel->rd_index->indnatts; i++)
        {
            if (indrel->rd_index->indkey.values[i] == attnum)
            {
                indattnum = i + 1;
                break;
            }
        }
 
        if (indattnum == 0)
        {
            index_close(indrel, lockmode);
            continue;
        }
 
        tuple = SearchSysCacheCopyAttNum(RelationGetRelid(indrel), indattnum);
 
        if (HeapTupleIsValid(tuple))
        {
            Form_pg_attribute attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
 
            if (setstorage)
                attrtuple->attstorage = newstorage;
 
            if (setcompression)
                attrtuple->attcompression = newcompression;
 
            CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
 
            InvokeObjectPostAlterHook(RelationRelationId,
                                      RelationGetRelid(rel),
                                      attrtuple->attnum);
 
            heap_freetuple(tuple);
        }
 
        index_close(indrel, lockmode);
    }
}
 
/*
 * ALTER TABLE ALTER COLUMN SET STORAGE
 *
 * Return value is the address of the modified column
 */
static ObjectAddress
ATExecSetStorage(Relation rel, const char *colName, Node *newValue, LOCKMODE lockmode)
{
    Relation    attrelation;
    HeapTuple   tuple;
    Form_pg_attribute attrtuple;
    AttrNumber  attnum;
    ObjectAddress address;
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
 
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
    attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
 
    attnum = attrtuple->attnum;
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    attrtuple->attstorage = GetAttributeStorage(attrtuple->atttypid, strVal(newValue));
 
    CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              attrtuple->attnum);
 
    /*
     * Apply the change to indexes as well (only for simple index columns,
     * matching behavior of index.c ConstructTupleDescriptor()).
     */
    SetIndexStorageProperties(rel, attrelation, attnum,
                              true, attrtuple->attstorage,
                              false, 0,
                              lockmode);
 
    heap_freetuple(tuple);
 
    table_close(attrelation, RowExclusiveLock);
 
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    return address;
}
 
 
/*
 * ALTER TABLE DROP COLUMN
 *
 * DROP COLUMN cannot use the normal ALTER TABLE recursion mechanism,
 * because we have to decide at runtime whether to recurse or not depending
 * on whether attinhcount goes to zero or not.  (We can't check this in a
 * static pre-pass because it won't handle multiple inheritance situations
 * correctly.)
 */
static void
ATPrepDropColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
                 AlterTableCmd *cmd, LOCKMODE lockmode,
                 AlterTableUtilityContext *context)
{
    if (rel->rd_rel->reloftype && !recursing)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot drop column from typed table")));
 
    if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
        ATTypedTableRecursion(wqueue, rel, cmd, lockmode, context);
 
    if (recurse)
        cmd->recurse = true;
}
 
/*
 * Drops column 'colName' from relation 'rel' and returns the address of the
 * dropped column.  The column is also dropped (or marked as no longer
 * inherited from relation) from the relation's inheritance children, if any.
 *
 * In the recursive invocations for inheritance child relations, instead of
 * dropping the column directly (if to be dropped at all), its object address
 * is added to 'addrs', which must be non-NULL in such invocations.  All
 * columns are dropped at the same time after all the children have been
 * checked recursively.
 */
static ObjectAddress
ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
                 DropBehavior behavior,
                 bool recurse, bool recursing,
                 bool missing_ok, LOCKMODE lockmode,
                 ObjectAddresses *addrs)
{
    HeapTuple   tuple;
    Form_pg_attribute targetatt;
    AttrNumber  attnum;
    List       *children;
    ObjectAddress object;
    bool        is_expr;
 
    /* At top level, permission check was done in ATPrepCmd, else do it */
    if (recursing)
        ATSimplePermissions(AT_DropColumn, rel,
                            ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
 
    /* Initialize addrs on the first invocation */
    Assert(!recursing || addrs != NULL);
 
    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();
 
    if (!recursing)
        addrs = new_object_addresses();
 
    /*
     * get the number of the attribute
     */
    tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
    {
        if (!missing_ok)
        {
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" of relation \"%s\" does not exist",
                            colName, RelationGetRelationName(rel))));
        }
        else
        {
            ereport(NOTICE,
                    (errmsg("column \"%s\" of relation \"%s\" does not exist, skipping",
                            colName, RelationGetRelationName(rel))));
            return InvalidObjectAddress;
        }
    }
    targetatt = (Form_pg_attribute) GETSTRUCT(tuple);
 
    attnum = targetatt->attnum;
 
    /* Can't drop a system attribute */
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot drop system column \"%s\"",
                        colName)));
 
    /*
     * Don't drop inherited columns, unless recursing (presumably from a drop
     * of the parent column)
     */
    if (targetatt->attinhcount > 0 && !recursing)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot drop inherited column \"%s\"",
                        colName)));
 
    /*
     * Don't drop columns used in the partition key, either.  (If we let this
     * go through, the key column's dependencies would cause a cascaded drop
     * of the whole table, which is surely not what the user expected.)
     */
    if (has_partition_attrs(rel,
                            bms_make_singleton(attnum - FirstLowInvalidHeapAttributeNumber),
                            &is_expr))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot drop column \"%s\" because it is part of the partition key of relation \"%s\"",
                        colName, RelationGetRelationName(rel))));
 
    ReleaseSysCache(tuple);
 
    /*
     * Propagate to children as appropriate.  Unlike most other ALTER
     * routines, we have to do this one level of recursion at a time; we can't
     * use find_all_inheritors to do it in one pass.
     */
    children =
        find_inheritance_children(RelationGetRelid(rel), lockmode);
 
    if (children)
    {
        Relation    attr_rel;
        ListCell   *child;
 
        /*
         * In case of a partitioned table, the column must be dropped from the
         * partitions as well.
         */
        if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE && !recurse)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("cannot drop column from only the partitioned table when partitions exist"),
                     errhint("Do not specify the ONLY keyword.")));
 
        attr_rel = table_open(AttributeRelationId, RowExclusiveLock);
        foreach(child, children)
        {
            Oid         childrelid = lfirst_oid(child);
            Relation    childrel;
            Form_pg_attribute childatt;
 
            /* find_inheritance_children already got lock */
            childrel = table_open(childrelid, NoLock);
            CheckAlterTableIsSafe(childrel);
 
            tuple = SearchSysCacheCopyAttName(childrelid, colName);
            if (!HeapTupleIsValid(tuple))   /* shouldn't happen */
                elog(ERROR, "cache lookup failed for attribute \"%s\" of relation %u",
                     colName, childrelid);
            childatt = (Form_pg_attribute) GETSTRUCT(tuple);
 
            if (childatt->attinhcount <= 0) /* shouldn't happen */
                elog(ERROR, "relation %u has non-inherited attribute \"%s\"",
                     childrelid, colName);
 
            if (recurse)
            {
                /*
                 * If the child column has other definition sources, just
                 * decrement its inheritance count; if not, recurse to delete
                 * it.
                 */
                if (childatt->attinhcount == 1 && !childatt->attislocal)
                {
                    /* Time to delete this child column, too */
                    ATExecDropColumn(wqueue, childrel, colName,
                                     behavior, true, true,
                                     false, lockmode, addrs);
                }
                else
                {
                    /* Child column must survive my deletion */
                    childatt->attinhcount--;
 
                    CatalogTupleUpdate(attr_rel, &tuple->t_self, tuple);
 
                    /* Make update visible */
                    CommandCounterIncrement();
                }
            }
            else
            {
                /*
                 * If we were told to drop ONLY in this table (no recursion),
                 * we need to mark the inheritors' attributes as locally
                 * defined rather than inherited.
                 */
                childatt->attinhcount--;
                childatt->attislocal = true;
 
                CatalogTupleUpdate(attr_rel, &tuple->t_self, tuple);
 
                /* Make update visible */
                CommandCounterIncrement();
            }
 
            heap_freetuple(tuple);
 
            table_close(childrel, NoLock);
        }
        table_close(attr_rel, RowExclusiveLock);
    }
 
    /* Add object to delete */
    object.classId = RelationRelationId;
    object.objectId = RelationGetRelid(rel);
    object.objectSubId = attnum;
    add_exact_object_address(&object, addrs);
 
    if (!recursing)
    {
        /* Recursion has ended, drop everything that was collected */
        performMultipleDeletions(addrs, behavior, 0);
        free_object_addresses(addrs);
    }
 
    return object;
}
 
/*
 * ALTER TABLE ADD INDEX
 *
 * There is no such command in the grammar, but parse_utilcmd.c converts
 * UNIQUE and PRIMARY KEY constraints into AT_AddIndex subcommands.  This lets
 * us schedule creation of the index at the appropriate time during ALTER.
 *
 * Return value is the address of the new index.
 */
static ObjectAddress
ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
               IndexStmt *stmt, bool is_rebuild, LOCKMODE lockmode)
{
    bool        check_rights;
    bool        skip_build;
    bool        quiet;
    ObjectAddress address;
 
    Assert(IsA(stmt, IndexStmt));
    Assert(!stmt->concurrent);
 
    /* The IndexStmt has already been through transformIndexStmt */
    Assert(stmt->transformed);
 
    /* suppress schema rights check when rebuilding existing index */
    check_rights = !is_rebuild;
    /* skip index build if phase 3 will do it or we're reusing an old one */
    skip_build = tab->rewrite > 0 || RelFileNumberIsValid(stmt->oldNumber);
    /* suppress notices when rebuilding existing index */
    quiet = is_rebuild;
 
    address = DefineIndex(RelationGetRelid(rel),
                          stmt,
                          InvalidOid,   /* no predefined OID */
                          InvalidOid,   /* no parent index */
                          InvalidOid,   /* no parent constraint */
                          -1,   /* total_parts unknown */
                          true, /* is_alter_table */
                          check_rights,
                          false,    /* check_not_in_use - we did it already */
                          skip_build,
                          quiet);
 
    /*
     * If TryReuseIndex() stashed a relfilenumber for us, we used it for the
     * new index instead of building from scratch.  Restore associated fields.
     * This may store InvalidSubTransactionId in both fields, in which case
     * relcache.c will assume it can rebuild the relcache entry.  Hence, do
     * this after the CCI that made catalog rows visible to any rebuild.  The
     * DROP of the old edition of this index will have scheduled the storage
     * for deletion at commit, so cancel that pending deletion.
     */
    if (RelFileNumberIsValid(stmt->oldNumber))
    {
        Relation    irel = index_open(address.objectId, NoLock);
 
        irel->rd_createSubid = stmt->oldCreateSubid;
        irel->rd_firstRelfilelocatorSubid = stmt->oldFirstRelfilelocatorSubid;
        RelationPreserveStorage(irel->rd_locator, true);
        index_close(irel, NoLock);
    }
 
    return address;
}
 
/*
 * ALTER TABLE ADD STATISTICS
 *
 * This is no such command in the grammar, but we use this internally to add
 * AT_ReAddStatistics subcommands to rebuild extended statistics after a table
 * column type change.
 */
static ObjectAddress
ATExecAddStatistics(AlteredTableInfo *tab, Relation rel,
                    CreateStatsStmt *stmt, bool is_rebuild, LOCKMODE lockmode)
{
    ObjectAddress address;
 
    Assert(IsA(stmt, CreateStatsStmt));
 
    /* The CreateStatsStmt has already been through transformStatsStmt */
    Assert(stmt->transformed);
 
    address = CreateStatistics(stmt);
 
    return address;
}
 
/*
 * ALTER TABLE ADD CONSTRAINT USING INDEX
 *
 * Returns the address of the new constraint.
 */
static ObjectAddress
ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
                         IndexStmt *stmt, LOCKMODE lockmode)
{
    Oid         index_oid = stmt->indexOid;
    Relation    indexRel;
    char       *indexName;
    IndexInfo  *indexInfo;
    char       *constraintName;
    char        constraintType;
    ObjectAddress address;
    bits16      flags;
 
    Assert(IsA(stmt, IndexStmt));
    Assert(OidIsValid(index_oid));
    Assert(stmt->isconstraint);
 
    /*
     * Doing this on partitioned tables is not a simple feature to implement,
     * so let's punt for now.
     */
    if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("ALTER TABLE / ADD CONSTRAINT USING INDEX is not supported on partitioned tables")));
 
    indexRel = index_open(index_oid, AccessShareLock);
 
    indexName = pstrdup(RelationGetRelationName(indexRel));
 
    indexInfo = BuildIndexInfo(indexRel);
 
    /* this should have been checked at parse time */
    if (!indexInfo->ii_Unique)
        elog(ERROR, "index \"%s\" is not unique", indexName);
 
    /*
     * Determine name to assign to constraint.  We require a constraint to
     * have the same name as the underlying index; therefore, use the index's
     * existing name as the default constraint name, and if the user
     * explicitly gives some other name for the constraint, rename the index
     * to match.
     */
    constraintName = stmt->idxname;
    if (constraintName == NULL)
        constraintName = indexName;
    else if (strcmp(constraintName, indexName) != 0)
    {
        ereport(NOTICE,
                (errmsg("ALTER TABLE / ADD CONSTRAINT USING INDEX will rename index \"%s\" to \"%s\"",
                        indexName, constraintName)));
        RenameRelationInternal(index_oid, constraintName, false, true);
    }
 
    /* Extra checks needed if making primary key */
    if (stmt->primary)
        index_check_primary_key(rel, indexInfo, true, stmt);
 
    /* Note we currently don't support EXCLUSION constraints here */
    if (stmt->primary)
        constraintType = CONSTRAINT_PRIMARY;
    else
        constraintType = CONSTRAINT_UNIQUE;
 
    /* Create the catalog entries for the constraint */
    flags = INDEX_CONSTR_CREATE_UPDATE_INDEX |
        INDEX_CONSTR_CREATE_REMOVE_OLD_DEPS |
        (stmt->initdeferred ? INDEX_CONSTR_CREATE_INIT_DEFERRED : 0) |
        (stmt->deferrable ? INDEX_CONSTR_CREATE_DEFERRABLE : 0) |
        (stmt->primary ? INDEX_CONSTR_CREATE_MARK_AS_PRIMARY : 0);
 
    address = index_constraint_create(rel,
                                      index_oid,
                                      InvalidOid,
                                      indexInfo,
                                      constraintName,
                                      constraintType,
                                      flags,
                                      allowSystemTableMods,
                                      false);   /* is_internal */
 
    index_close(indexRel, NoLock);
 
    return address;
}
 
/*
 * ALTER TABLE ADD CONSTRAINT
 *
 * Return value is the address of the new constraint; if no constraint was
 * added, InvalidObjectAddress is returned.
 */
static ObjectAddress
ATExecAddConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
                    Constraint *newConstraint, bool recurse, bool is_readd,
                    LOCKMODE lockmode)
{
    ObjectAddress address = InvalidObjectAddress;
 
    Assert(IsA(newConstraint, Constraint));
 
    /*
     * Currently, we only expect to see CONSTR_CHECK and CONSTR_FOREIGN nodes
     * arriving here (see the preprocessing done in parse_utilcmd.c).  Use a
     * switch anyway to make it easier to add more code later.
     */
    switch (newConstraint->contype)
    {
        case CONSTR_CHECK:
            address =
                ATAddCheckConstraint(wqueue, tab, rel,
                                     newConstraint, recurse, false, is_readd,
                                     lockmode);
            break;
 
        case CONSTR_FOREIGN:
 
            /*
             * Assign or validate constraint name
             */
            if (newConstraint->conname)
            {
                if (ConstraintNameIsUsed(CONSTRAINT_RELATION,
                                         RelationGetRelid(rel),
                                         newConstraint->conname))
                    ereport(ERROR,
                            (errcode(ERRCODE_DUPLICATE_OBJECT),
                             errmsg("constraint \"%s\" for relation \"%s\" already exists",
                                    newConstraint->conname,
                                    RelationGetRelationName(rel))));
            }
            else
                newConstraint->conname =
                    ChooseConstraintName(RelationGetRelationName(rel),
                                         ChooseForeignKeyConstraintNameAddition(newConstraint->fk_attrs),
                                         "fkey",
                                         RelationGetNamespace(rel),
                                         NIL);
 
            address = ATAddForeignKeyConstraint(wqueue, tab, rel,
                                                newConstraint,
                                                recurse, false,
                                                lockmode);
            break;
 
        default:
            elog(ERROR, "unrecognized constraint type: %d",
                 (int) newConstraint->contype);
    }
 
    return address;
}
 
/*
 * Generate the column-name portion of the constraint name for a new foreign
 * key given the list of column names that reference the referenced
 * table.  This will be passed to ChooseConstraintName along with the parent
 * table name and the "fkey" suffix.
 *
 * We know that less than NAMEDATALEN characters will actually be used, so we
 * can truncate the result once we've generated that many.
 *
 * XXX see also ChooseExtendedStatisticNameAddition and
 * ChooseIndexNameAddition.
 */
static char *
ChooseForeignKeyConstraintNameAddition(List *colnames)
{
    char        buf[NAMEDATALEN * 2];
    int         buflen = 0;
    ListCell   *lc;
 
    buf[0] = '\0';
    foreach(lc, colnames)
    {
        const char *name = strVal(lfirst(lc));
 
        if (buflen > 0)
            buf[buflen++] = '_';    /* insert _ between names */
 
        /*
         * At this point we have buflen <= NAMEDATALEN.  name should be less
         * than NAMEDATALEN already, but use strlcpy for paranoia.
         */
        strlcpy(buf + buflen, name, NAMEDATALEN);
        buflen += strlen(buf + buflen);
        if (buflen >= NAMEDATALEN)
            break;
    }
    return pstrdup(buf);
}
 
/*
 * Add a check constraint to a single table and its children.  Returns the
 * address of the constraint added to the parent relation, if one gets added,
 * or InvalidObjectAddress otherwise.
 *
 * Subroutine for ATExecAddConstraint.
 *
 * We must recurse to child tables during execution, rather than using
 * ALTER TABLE's normal prep-time recursion.  The reason is that all the
 * constraints *must* be given the same name, else they won't be seen as
 * related later.  If the user didn't explicitly specify a name, then
 * AddRelationNewConstraints would normally assign different names to the
 * child constraints.  To fix that, we must capture the name assigned at
 * the parent table and pass that down.
 */
static ObjectAddress
ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
                     Constraint *constr, bool recurse, bool recursing,
                     bool is_readd, LOCKMODE lockmode)
{
    List       *newcons;
    ListCell   *lcon;
    List       *children;
    ListCell   *child;
    ObjectAddress address = InvalidObjectAddress;
 
    /* At top level, permission check was done in ATPrepCmd, else do it */
    if (recursing)
        ATSimplePermissions(AT_AddConstraint, rel,
                            ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
 
    /*
     * Call AddRelationNewConstraints to do the work, making sure it works on
     * a copy of the Constraint so transformExpr can't modify the original. It
     * returns a list of cooked constraints.
     *
     * If the constraint ends up getting merged with a pre-existing one, it's
     * omitted from the returned list, which is what we want: we do not need
     * to do any validation work.  That can only happen at child tables,
     * though, since we disallow merging at the top level.
     */
    newcons = AddRelationNewConstraints(rel, NIL,
                                        list_make1(copyObject(constr)),
                                        recursing || is_readd,  /* allow_merge */
                                        !recursing, /* is_local */
                                        is_readd,   /* is_internal */
                                        NULL);  /* queryString not available
                                                 * here */
 
    /* we don't expect more than one constraint here */
    Assert(list_length(newcons) <= 1);
 
    /* Add each to-be-validated constraint to Phase 3's queue */
    foreach(lcon, newcons)
    {
        CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon);
 
        if (!ccon->skip_validation)
        {
            NewConstraint *newcon;
 
            newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
            newcon->name = ccon->name;
            newcon->contype = ccon->contype;
            newcon->qual = ccon->expr;
 
            tab->constraints = lappend(tab->constraints, newcon);
        }
 
        /* Save the actually assigned name if it was defaulted */
        if (constr->conname == NULL)
            constr->conname = ccon->name;
 
        ObjectAddressSet(address, ConstraintRelationId, ccon->conoid);
    }
 
    /* At this point we must have a locked-down name to use */
    Assert(constr->conname != NULL);
 
    /* Advance command counter in case same table is visited multiple times */
    CommandCounterIncrement();
 
    /*
     * If the constraint got merged with an existing constraint, we're done.
     * We mustn't recurse to child tables in this case, because they've
     * already got the constraint, and visiting them again would lead to an
     * incorrect value for coninhcount.
     */
    if (newcons == NIL)
        return address;
 
    /*
     * If adding a NO INHERIT constraint, no need to find our children.
     */
    if (constr->is_no_inherit)
        return address;
 
    /*
     * Propagate to children as appropriate.  Unlike most other ALTER
     * routines, we have to do this one level of recursion at a time; we can't
     * use find_all_inheritors to do it in one pass.
     */
    children =
        find_inheritance_children(RelationGetRelid(rel), lockmode);
 
    /*
     * Check if ONLY was specified with ALTER TABLE.  If so, allow the
     * constraint creation only if there are no children currently.  Error out
     * otherwise.
     */
    if (!recurse && children != NIL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("constraint must be added to child tables too")));
 
    foreach(child, children)
    {
        Oid         childrelid = lfirst_oid(child);
        Relation    childrel;
        AlteredTableInfo *childtab;
 
        /* find_inheritance_children already got lock */
        childrel = table_open(childrelid, NoLock);
        CheckAlterTableIsSafe(childrel);
 
        /* Find or create work queue entry for this table */
        childtab = ATGetQueueEntry(wqueue, childrel);
 
        /* Recurse to child */
        ATAddCheckConstraint(wqueue, childtab, childrel,
                             constr, recurse, true, is_readd, lockmode);
 
        table_close(childrel, NoLock);
    }
 
    return address;
}
 
/*
 * Add a foreign-key constraint to a single table; return the new constraint's
 * address.
 *
 * Subroutine for ATExecAddConstraint.  Must already hold exclusive
 * lock on the rel, and have done appropriate validity checks for it.
 * We do permissions checks here, however.
 *
 * When the referenced or referencing tables (or both) are partitioned,
 * multiple pg_constraint rows are required -- one for each partitioned table
 * and each partition on each side (fortunately, not one for every combination
 * thereof).  We also need action triggers on each leaf partition on the
 * referenced side, and check triggers on each leaf partition on the
 * referencing side.
 */
static ObjectAddress
ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
                          Constraint *fkconstraint,
                          bool recurse, bool recursing, LOCKMODE lockmode)
{
    Relation    pkrel;
    int16       pkattnum[INDEX_MAX_KEYS] = {0};
    int16       fkattnum[INDEX_MAX_KEYS] = {0};
    Oid         pktypoid[INDEX_MAX_KEYS] = {0};
    Oid         fktypoid[INDEX_MAX_KEYS] = {0};
    Oid         opclasses[INDEX_MAX_KEYS] = {0};
    Oid         pfeqoperators[INDEX_MAX_KEYS] = {0};
    Oid         ppeqoperators[INDEX_MAX_KEYS] = {0};
    Oid         ffeqoperators[INDEX_MAX_KEYS] = {0};
    int16       fkdelsetcols[INDEX_MAX_KEYS] = {0};
    bool        with_period;
    bool        pk_has_without_overlaps;
    int         i;
    int         numfks,
                numpks,
                numfkdelsetcols;
    Oid         indexOid;
    bool        old_check_ok;
    ObjectAddress address;
    ListCell   *old_pfeqop_item = list_head(fkconstraint->old_conpfeqop);
 
    /*
     * Grab ShareRowExclusiveLock on the pk table, so that someone doesn't
     * delete rows out from under us.
     */
    if (OidIsValid(fkconstraint->old_pktable_oid))
        pkrel = table_open(fkconstraint->old_pktable_oid, ShareRowExclusiveLock);
    else
        pkrel = table_openrv(fkconstraint->pktable, ShareRowExclusiveLock);
 
    /*
     * Validity checks (permission checks wait till we have the column
     * numbers)
     */
    if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        if (!recurse)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot use ONLY for foreign key on partitioned table \"%s\" referencing relation \"%s\"",
                            RelationGetRelationName(rel),
                            RelationGetRelationName(pkrel))));
        if (fkconstraint->skip_validation && !fkconstraint->initially_valid)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot add NOT VALID foreign key on partitioned table \"%s\" referencing relation \"%s\"",
                            RelationGetRelationName(rel),
                            RelationGetRelationName(pkrel)),
                     errdetail("This feature is not yet supported on partitioned tables.")));
    }
 
    if (pkrel->rd_rel->relkind != RELKIND_RELATION &&
        pkrel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("referenced relation \"%s\" is not a table",
                        RelationGetRelationName(pkrel))));
 
    if (!allowSystemTableMods && IsSystemRelation(pkrel))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: \"%s\" is a system catalog",
                        RelationGetRelationName(pkrel))));
 
    /*
     * References from permanent or unlogged tables to temp tables, and from
     * permanent tables to unlogged tables, are disallowed because the
     * referenced data can vanish out from under us.  References from temp
     * tables to any other table type are also disallowed, because other
     * backends might need to run the RI triggers on the perm table, but they
     * can't reliably see tuples in the local buffers of other backends.
     */
    switch (rel->rd_rel->relpersistence)
    {
        case RELPERSISTENCE_PERMANENT:
            if (!RelationIsPermanent(pkrel))
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("constraints on permanent tables may reference only permanent tables")));
            break;
        case RELPERSISTENCE_UNLOGGED:
            if (!RelationIsPermanent(pkrel)
                && pkrel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("constraints on unlogged tables may reference only permanent or unlogged tables")));
            break;
        case RELPERSISTENCE_TEMP:
            if (pkrel->rd_rel->relpersistence != RELPERSISTENCE_TEMP)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("constraints on temporary tables may reference only temporary tables")));
            if (!pkrel->rd_islocaltemp || !rel->rd_islocaltemp)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("constraints on temporary tables must involve temporary tables of this session")));
            break;
    }
 
    /*
     * Look up the referencing attributes to make sure they exist, and record
     * their attnums and type OIDs.
     */
    numfks = transformColumnNameList(RelationGetRelid(rel),
                                     fkconstraint->fk_attrs,
                                     fkattnum, fktypoid);
    with_period = fkconstraint->fk_with_period || fkconstraint->pk_with_period;
    if (with_period && !fkconstraint->fk_with_period)
        ereport(ERROR,
                errcode(ERRCODE_INVALID_FOREIGN_KEY),
                errmsg("foreign key uses PERIOD on the referenced table but not the referencing table"));
 
    numfkdelsetcols = transformColumnNameList(RelationGetRelid(rel),
                                              fkconstraint->fk_del_set_cols,
                                              fkdelsetcols, NULL);
    validateFkOnDeleteSetColumns(numfks, fkattnum,
                                 numfkdelsetcols, fkdelsetcols,
                                 fkconstraint->fk_del_set_cols);
 
    /*
     * If the attribute list for the referenced table was omitted, lookup the
     * definition of the primary key and use it.  Otherwise, validate the
     * supplied attribute list.  In either case, discover the index OID and
     * index opclasses, and the attnums and type OIDs of the attributes.
     */
    if (fkconstraint->pk_attrs == NIL)
    {
        numpks = transformFkeyGetPrimaryKey(pkrel, &indexOid,
                                            &fkconstraint->pk_attrs,
                                            pkattnum, pktypoid,
                                            opclasses, &pk_has_without_overlaps);
 
        /* If the primary key uses WITHOUT OVERLAPS, the fk must use PERIOD */
        if (pk_has_without_overlaps && !fkconstraint->fk_with_period)
            ereport(ERROR,
                    errcode(ERRCODE_INVALID_FOREIGN_KEY),
                    errmsg("foreign key uses PERIOD on the referenced table but not the referencing table"));
    }
    else
    {
        numpks = transformColumnNameList(RelationGetRelid(pkrel),
                                         fkconstraint->pk_attrs,
                                         pkattnum, pktypoid);
 
        /* Since we got pk_attrs, one should be a period. */
        if (with_period && !fkconstraint->pk_with_period)
            ereport(ERROR,
                    errcode(ERRCODE_INVALID_FOREIGN_KEY),
                    errmsg("foreign key uses PERIOD on the referencing table but not the referenced table"));
 
        /* Look for an index matching the column list */
        indexOid = transformFkeyCheckAttrs(pkrel, numpks, pkattnum,
                                           with_period, opclasses, &pk_has_without_overlaps);
    }
 
    /*
     * If the referenced primary key has WITHOUT OVERLAPS, the foreign key
     * must use PERIOD.
     */
    if (pk_has_without_overlaps && !with_period)
        ereport(ERROR,
                errcode(ERRCODE_INVALID_FOREIGN_KEY),
                errmsg("foreign key must use PERIOD when referencing a primary using WITHOUT OVERLAPS"));
 
    /*
     * Now we can check permissions.
     */
    checkFkeyPermissions(pkrel, pkattnum, numpks);
 
    /*
     * Check some things for generated columns.
     */
    for (i = 0; i < numfks; i++)
    {
        char        attgenerated = TupleDescAttr(RelationGetDescr(rel), fkattnum[i] - 1)->attgenerated;
 
        if (attgenerated)
        {
            /*
             * Check restrictions on UPDATE/DELETE actions, per SQL standard
             */
            if (fkconstraint->fk_upd_action == FKCONSTR_ACTION_SETNULL ||
                fkconstraint->fk_upd_action == FKCONSTR_ACTION_SETDEFAULT ||
                fkconstraint->fk_upd_action == FKCONSTR_ACTION_CASCADE)
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                         errmsg("invalid %s action for foreign key constraint containing generated column",
                                "ON UPDATE")));
            if (fkconstraint->fk_del_action == FKCONSTR_ACTION_SETNULL ||
                fkconstraint->fk_del_action == FKCONSTR_ACTION_SETDEFAULT)
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                         errmsg("invalid %s action for foreign key constraint containing generated column",
                                "ON DELETE")));
        }
    }
 
    /*
     * Some actions are currently unsupported for foreign keys using PERIOD.
     */
    if (fkconstraint->fk_with_period)
    {
        if (fkconstraint->fk_upd_action == FKCONSTR_ACTION_CASCADE ||
            fkconstraint->fk_upd_action == FKCONSTR_ACTION_SETNULL ||
            fkconstraint->fk_upd_action == FKCONSTR_ACTION_SETDEFAULT)
            ereport(ERROR,
                    errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                    errmsg("unsupported %s action for foreign key constraint using PERIOD",
                           "ON UPDATE"));
 
        if (fkconstraint->fk_del_action == FKCONSTR_ACTION_CASCADE ||
            fkconstraint->fk_del_action == FKCONSTR_ACTION_SETNULL ||
            fkconstraint->fk_del_action == FKCONSTR_ACTION_SETDEFAULT)
            ereport(ERROR,
                    errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                    errmsg("unsupported %s action for foreign key constraint using PERIOD",
                           "ON DELETE"));
    }
 
    /*
     * Look up the equality operators to use in the constraint.
     *
     * Note that we have to be careful about the difference between the actual
     * PK column type and the opclass' declared input type, which might be
     * only binary-compatible with it.  The declared opcintype is the right
     * thing to probe pg_amop with.
     */
    if (numfks != numpks)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_FOREIGN_KEY),
                 errmsg("number of referencing and referenced columns for foreign key disagree")));
 
    /*
     * On the strength of a previous constraint, we might avoid scanning
     * tables to validate this one.  See below.
     */
    old_check_ok = (fkconstraint->old_conpfeqop != NIL);
    Assert(!old_check_ok || numfks == list_length(fkconstraint->old_conpfeqop));
 
    for (i = 0; i < numpks; i++)
    {
        Oid         pktype = pktypoid[i];
        Oid         fktype = fktypoid[i];
        Oid         fktyped;
        HeapTuple   cla_ht;
        Form_pg_opclass cla_tup;
        Oid         amid;
        Oid         opfamily;
        Oid         opcintype;
        Oid         pfeqop;
        Oid         ppeqop;
        Oid         ffeqop;
        int16       eqstrategy;
        Oid         pfeqop_right;
 
        /* We need several fields out of the pg_opclass entry */
        cla_ht = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclasses[i]));
        if (!HeapTupleIsValid(cla_ht))
            elog(ERROR, "cache lookup failed for opclass %u", opclasses[i]);
        cla_tup = (Form_pg_opclass) GETSTRUCT(cla_ht);
        amid = cla_tup->opcmethod;
        opfamily = cla_tup->opcfamily;
        opcintype = cla_tup->opcintype;
        ReleaseSysCache(cla_ht);
 
        if (with_period)
        {
            StrategyNumber rtstrategy;
            bool        for_overlaps = with_period && i == numpks - 1;
 
            /*
             * GiST indexes are required to support temporal foreign keys
             * because they combine equals and overlaps.
             */
            if (amid != GIST_AM_OID)
                elog(ERROR, "only GiST indexes are supported for temporal foreign keys");
 
            rtstrategy = for_overlaps ? RTOverlapStrategyNumber : RTEqualStrategyNumber;
 
            /*
             * An opclass can use whatever strategy numbers it wants, so we
             * ask the opclass what number it actually uses instead of our RT*
             * constants.
             */
            eqstrategy = GistTranslateStratnum(opclasses[i], rtstrategy);
            if (eqstrategy == InvalidStrategy)
            {
                HeapTuple   tuple;
 
                tuple = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclasses[i]));
                if (!HeapTupleIsValid(tuple))
                    elog(ERROR, "cache lookup failed for operator class %u", opclasses[i]);
 
                ereport(ERROR,
                        errcode(ERRCODE_UNDEFINED_OBJECT),
                        for_overlaps
                        ? errmsg("could not identify an overlaps operator for foreign key")
                        : errmsg("could not identify an equality operator for foreign key"),
                        errdetail("Could not translate strategy number %d for operator class \"%s\" for access method \"%s\".",
                                  rtstrategy, NameStr(((Form_pg_opclass) GETSTRUCT(tuple))->opcname), "gist"));
            }
        }
        else
        {
            /*
             * Check it's a btree; currently this can never fail since no
             * other index AMs support unique indexes.  If we ever did have
             * other types of unique indexes, we'd need a way to determine
             * which operator strategy number is equality.  (We could use
             * something like GistTranslateStratnum.)
             */
            if (amid != BTREE_AM_OID)
                elog(ERROR, "only b-tree indexes are supported for foreign keys");
            eqstrategy = BTEqualStrategyNumber;
        }
 
        /*
         * There had better be a primary equality operator for the index.
         * We'll use it for PK = PK comparisons.
         */
        ppeqop = get_opfamily_member(opfamily, opcintype, opcintype,
                                     eqstrategy);
 
        if (!OidIsValid(ppeqop))
            elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
                 eqstrategy, opcintype, opcintype, opfamily);
 
        /*
         * Are there equality operators that take exactly the FK type? Assume
         * we should look through any domain here.
         */
        fktyped = getBaseType(fktype);
 
        pfeqop = get_opfamily_member(opfamily, opcintype, fktyped,
                                     eqstrategy);
        if (OidIsValid(pfeqop))
        {
            pfeqop_right = fktyped;
            ffeqop = get_opfamily_member(opfamily, fktyped, fktyped,
                                         eqstrategy);
        }
        else
        {
            /* keep compiler quiet */
            pfeqop_right = InvalidOid;
            ffeqop = InvalidOid;
        }
 
        if (!(OidIsValid(pfeqop) && OidIsValid(ffeqop)))
        {
            /*
             * Otherwise, look for an implicit cast from the FK type to the
             * opcintype, and if found, use the primary equality operator.
             * This is a bit tricky because opcintype might be a polymorphic
             * type such as ANYARRAY or ANYENUM; so what we have to test is
             * whether the two actual column types can be concurrently cast to
             * that type.  (Otherwise, we'd fail to reject combinations such
             * as int[] and point[].)
             */
            Oid         input_typeids[2];
            Oid         target_typeids[2];
 
            input_typeids[0] = pktype;
            input_typeids[1] = fktype;
            target_typeids[0] = opcintype;
            target_typeids[1] = opcintype;
            if (can_coerce_type(2, input_typeids, target_typeids,
                                COERCION_IMPLICIT))
            {
                pfeqop = ffeqop = ppeqop;
                pfeqop_right = opcintype;
            }
        }
 
        if (!(OidIsValid(pfeqop) && OidIsValid(ffeqop)))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("foreign key constraint \"%s\" cannot be implemented",
                            fkconstraint->conname),
                     errdetail("Key columns \"%s\" and \"%s\" "
                               "are of incompatible types: %s and %s.",
                               strVal(list_nth(fkconstraint->fk_attrs, i)),
                               strVal(list_nth(fkconstraint->pk_attrs, i)),
                               format_type_be(fktype),
                               format_type_be(pktype))));
 
        if (old_check_ok)
        {
            /*
             * When a pfeqop changes, revalidate the constraint.  We could
             * permit intra-opfamily changes, but that adds subtle complexity
             * without any concrete benefit for core types.  We need not
             * assess ppeqop or ffeqop, which RI_Initial_Check() does not use.
             */
            old_check_ok = (pfeqop == lfirst_oid(old_pfeqop_item));
            old_pfeqop_item = lnext(fkconstraint->old_conpfeqop,
                                    old_pfeqop_item);
        }
        if (old_check_ok)
        {
            Oid         old_fktype;
            Oid         new_fktype;
            CoercionPathType old_pathtype;
            CoercionPathType new_pathtype;
            Oid         old_castfunc;
            Oid         new_castfunc;
            Form_pg_attribute attr = TupleDescAttr(tab->oldDesc,
                                                   fkattnum[i] - 1);
 
            /*
             * Identify coercion pathways from each of the old and new FK-side
             * column types to the right (foreign) operand type of the pfeqop.
             * We may assume that pg_constraint.conkey is not changing.
             */
            old_fktype = attr->atttypid;
            new_fktype = fktype;
            old_pathtype = findFkeyCast(pfeqop_right, old_fktype,
                                        &old_castfunc);
            new_pathtype = findFkeyCast(pfeqop_right, new_fktype,
                                        &new_castfunc);
 
            /*
             * Upon a change to the cast from the FK column to its pfeqop
             * operand, revalidate the constraint.  For this evaluation, a
             * binary coercion cast is equivalent to no cast at all.  While
             * type implementors should design implicit casts with an eye
             * toward consistency of operations like equality, we cannot
             * assume here that they have done so.
             *
             * A function with a polymorphic argument could change behavior
             * arbitrarily in response to get_fn_expr_argtype().  Therefore,
             * when the cast destination is polymorphic, we only avoid
             * revalidation if the input type has not changed at all.  Given
             * just the core data types and operator classes, this requirement
             * prevents no would-be optimizations.
             *
             * If the cast converts from a base type to a domain thereon, then
             * that domain type must be the opcintype of the unique index.
             * Necessarily, the primary key column must then be of the domain
             * type.  Since the constraint was previously valid, all values on
             * the foreign side necessarily exist on the primary side and in
             * turn conform to the domain.  Consequently, we need not treat
             * domains specially here.
             *
             * Since we require that all collations share the same notion of
             * equality (which they do, because texteq reduces to bitwise
             * equality), we don't compare collation here.
             *
             * We need not directly consider the PK type.  It's necessarily
             * binary coercible to the opcintype of the unique index column,
             * and ri_triggers.c will only deal with PK datums in terms of
             * that opcintype.  Changing the opcintype also changes pfeqop.
             */
            old_check_ok = (new_pathtype == old_pathtype &&
                            new_castfunc == old_castfunc &&
                            (!IsPolymorphicType(pfeqop_right) ||
                             new_fktype == old_fktype));
        }
 
        pfeqoperators[i] = pfeqop;
        ppeqoperators[i] = ppeqop;
        ffeqoperators[i] = ffeqop;
    }
 
    /*
     * For FKs with PERIOD we need additional operators to check whether the
     * referencing row's range is contained by the aggregated ranges of the
     * referenced row(s). For rangetypes and multirangetypes this is
     * fk.periodatt <@ range_agg(pk.periodatt). Those are the only types we
     * support for now. FKs will look these up at "runtime", but we should
     * make sure the lookup works here, even if we don't use the values.
     */
    if (with_period)
    {
        Oid         periodoperoid;
        Oid         aggedperiodoperoid;
 
        FindFKPeriodOpers(opclasses[numpks - 1], &periodoperoid, &aggedperiodoperoid);
    }
 
    /* First, create the constraint catalog entry itself. */
    address = addFkConstraint(addFkBothSides,
                              fkconstraint->conname, fkconstraint, rel, pkrel,
                              indexOid,
                              InvalidOid,   /* no parent constraint */
                              numfks,
                              pkattnum,
                              fkattnum,
                              pfeqoperators,
                              ppeqoperators,
                              ffeqoperators,
                              numfkdelsetcols,
                              fkdelsetcols,
                              false,
                              with_period);
 
    /* Next process the action triggers at the referenced side and recurse */
    addFkRecurseReferenced(fkconstraint, rel, pkrel,
                           indexOid,
                           address.objectId,
                           numfks,
                           pkattnum,
                           fkattnum,
                           pfeqoperators,
                           ppeqoperators,
                           ffeqoperators,
                           numfkdelsetcols,
                           fkdelsetcols,
                           old_check_ok,
                           InvalidOid, InvalidOid,
                           with_period);
 
    /* Lastly create the check triggers at the referencing side and recurse */
    addFkRecurseReferencing(wqueue, fkconstraint, rel, pkrel,
                            indexOid,
                            address.objectId,
                            numfks,
                            pkattnum,
                            fkattnum,
                            pfeqoperators,
                            ppeqoperators,
                            ffeqoperators,
                            numfkdelsetcols,
                            fkdelsetcols,
                            old_check_ok,
                            lockmode,
                            InvalidOid, InvalidOid,
                            with_period);
 
    /*
     * Done.  Close pk table, but keep lock until we've committed.
     */
    table_close(pkrel, NoLock);
 
    return address;
}
 
/*
 * validateFkOnDeleteSetColumns
 *      Verifies that columns used in ON DELETE SET NULL/DEFAULT (...)
 *      column lists are valid.
 */
void
validateFkOnDeleteSetColumns(int numfks, const int16 *fkattnums,
                             int numfksetcols, const int16 *fksetcolsattnums,
                             List *fksetcols)
{
    for (int i = 0; i < numfksetcols; i++)
    {
        int16       setcol_attnum = fksetcolsattnums[i];
        bool        seen = false;
 
        for (int j = 0; j < numfks; j++)
        {
            if (fkattnums[j] == setcol_attnum)
            {
                seen = true;
                break;
            }
        }
 
        if (!seen)
        {
            char       *col = strVal(list_nth(fksetcols, i));
 
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
                     errmsg("column \"%s\" referenced in ON DELETE SET action must be part of foreign key", col)));
        }
    }
}
 
/*
 * addFkConstraint
 *      Install pg_constraint entries to implement a foreign key constraint.
 *      Caller must separately invoke addFkRecurseReferenced and
 *      addFkRecurseReferencing, as appropriate, to install pg_trigger entries
 *      and (for partitioned tables) recurse to partitions.
 *
 * fkside: the side of the FK (or both) to create.  Caller should
 *      call addFkRecurseReferenced if this is addFkReferencedSide,
 *      addFkRecurseReferencing if it's addFkReferencingSide, or both if it's
 *      addFkBothSides.
 * constraintname: the base name for the constraint being added,
 *      copied to fkconstraint->conname if the latter is not set
 * fkconstraint: the constraint being added
 * rel: the root referencing relation
 * pkrel: the referenced relation; might be a partition, if recursing
 * indexOid: the OID of the index (on pkrel) implementing this constraint
 * parentConstr: the OID of a parent constraint; InvalidOid if this is a
 *      top-level constraint
 * numfks: the number of columns in the foreign key
 * pkattnum: the attnum array of referenced attributes
 * fkattnum: the attnum array of referencing attributes
 * pf/pp/ffeqoperators: OID array of operators between columns
 * numfkdelsetcols: the number of columns in the ON DELETE SET NULL/DEFAULT
 *      (...) clause
 * fkdelsetcols: the attnum array of the columns in the ON DELETE SET
 *      NULL/DEFAULT clause
 * with_period: true if this is a temporal FK
 */
static ObjectAddress
addFkConstraint(addFkConstraintSides fkside,
                char *constraintname, Constraint *fkconstraint,
                Relation rel, Relation pkrel, Oid indexOid, Oid parentConstr,
                int numfks, int16 *pkattnum,
                int16 *fkattnum, Oid *pfeqoperators, Oid *ppeqoperators,
                Oid *ffeqoperators, int numfkdelsetcols, int16 *fkdelsetcols,
                bool is_internal, bool with_period)
{
    ObjectAddress address;
    Oid         constrOid;
    char       *conname;
    bool        conislocal;
    int16       coninhcount;
    bool        connoinherit;
 
    /*
     * Verify relkind for each referenced partition.  At the top level, this
     * is redundant with a previous check, but we need it when recursing.
     */
    if (pkrel->rd_rel->relkind != RELKIND_RELATION &&
        pkrel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("referenced relation \"%s\" is not a table",
                        RelationGetRelationName(pkrel))));
 
    /*
     * Caller supplies us with a constraint name; however, it may be used in
     * this partition, so come up with a different one in that case.
     */
    if (ConstraintNameIsUsed(CONSTRAINT_RELATION,
                             RelationGetRelid(rel),
                             constraintname))
        conname = ChooseConstraintName(RelationGetRelationName(rel),
                                       ChooseForeignKeyConstraintNameAddition(fkconstraint->fk_attrs),
                                       "fkey",
                                       RelationGetNamespace(rel), NIL);
    else
        conname = constraintname;
 
    if (fkconstraint->conname == NULL)
        fkconstraint->conname = pstrdup(conname);
 
    if (OidIsValid(parentConstr))
    {
        conislocal = false;
        coninhcount = 1;
        connoinherit = false;
    }
    else
    {
        conislocal = true;
        coninhcount = 0;
 
        /*
         * always inherit for partitioned tables, never for legacy inheritance
         */
        connoinherit = rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE;
    }
 
    /*
     * Record the FK constraint in pg_constraint.
     */
    constrOid = CreateConstraintEntry(conname,
                                      RelationGetNamespace(rel),
                                      CONSTRAINT_FOREIGN,
                                      fkconstraint->deferrable,
                                      fkconstraint->initdeferred,
                                      fkconstraint->initially_valid,
                                      parentConstr,
                                      RelationGetRelid(rel),
                                      fkattnum,
                                      numfks,
                                      numfks,
                                      InvalidOid,   /* not a domain constraint */
                                      indexOid,
                                      RelationGetRelid(pkrel),
                                      pkattnum,
                                      pfeqoperators,
                                      ppeqoperators,
                                      ffeqoperators,
                                      numfks,
                                      fkconstraint->fk_upd_action,
                                      fkconstraint->fk_del_action,
                                      fkdelsetcols,
                                      numfkdelsetcols,
                                      fkconstraint->fk_matchtype,
                                      NULL, /* no exclusion constraint */
                                      NULL, /* no check constraint */
                                      NULL,
                                      conislocal,   /* islocal */
                                      coninhcount,  /* inhcount */
                                      connoinherit, /* conNoInherit */
                                      with_period,  /* conPeriod */
                                      is_internal); /* is_internal */
 
    ObjectAddressSet(address, ConstraintRelationId, constrOid);
 
    /*
     * In partitioning cases, create the dependency entries for this
     * constraint.  (For non-partitioned cases, relevant entries were created
     * by CreateConstraintEntry.)
     *
     * On the referenced side, we need the constraint to have an internal
     * dependency on its parent constraint; this means that this constraint
     * cannot be dropped on its own -- only through the parent constraint. It
     * also means the containing partition cannot be dropped on its own, but
     * it can be detached, at which point this dependency is removed (after
     * verifying that no rows are referenced via this FK.)
     *
     * When processing the referencing side, we link the constraint via the
     * special partitioning dependencies: the parent constraint is the primary
     * dependent, and the partition on which the foreign key exists is the
     * secondary dependency.  That way, this constraint is dropped if either
     * of these objects is.
     *
     * Note that this is only necessary for the subsidiary pg_constraint rows
     * in partitions; the topmost row doesn't need any of this.
     */
    if (OidIsValid(parentConstr))
    {
        ObjectAddress referenced;
 
        ObjectAddressSet(referenced, ConstraintRelationId, parentConstr);
 
        Assert(fkside != addFkBothSides);
        if (fkside == addFkReferencedSide)
            recordDependencyOn(&address, &referenced, DEPENDENCY_INTERNAL);
        else
        {
            recordDependencyOn(&address, &referenced, DEPENDENCY_PARTITION_PRI);
            ObjectAddressSet(referenced, RelationRelationId, RelationGetRelid(rel));
            recordDependencyOn(&address, &referenced, DEPENDENCY_PARTITION_SEC);
        }
    }
 
    /* make new constraint visible, in case we add more */
    CommandCounterIncrement();
 
    return address;
}
 
/*
 * addFkRecurseReferenced
 *      Recursive helper for the referenced side of foreign key creation,
 *      which creates the action triggers and recurses
 *
 * If the referenced relation is a plain relation, create the necessary action
 * triggers that implement the constraint.  If the referenced relation is a
 * partitioned table, then we create a pg_constraint row referencing the parent
 * of the referencing side for it and recurse on this routine for each
 * partition.
 *
 * fkconstraint: the constraint being added
 * rel: the root referencing relation
 * pkrel: the referenced relation; might be a partition, if recursing
 * indexOid: the OID of the index (on pkrel) implementing this constraint
 * parentConstr: the OID of a parent constraint; InvalidOid if this is a
 *      top-level constraint
 * numfks: the number of columns in the foreign key
 * pkattnum: the attnum array of referenced attributes
 * fkattnum: the attnum array of referencing attributes
 * numfkdelsetcols: the number of columns in the ON DELETE SET
 *      NULL/DEFAULT (...) clause
 * fkdelsetcols: the attnum array of the columns in the ON DELETE SET
 *      NULL/DEFAULT clause
 * pf/pp/ffeqoperators: OID array of operators between columns
 * old_check_ok: true if this constraint replaces an existing one that
 *      was already validated (thus this one doesn't need validation)
 * parentDelTrigger and parentUpdTrigger: when recursively called on a
 *      partition, the OIDs of the parent action triggers for DELETE and
 *      UPDATE respectively.
 * with_period: true if this is a temporal FK
 */
static void
addFkRecurseReferenced(Constraint *fkconstraint, Relation rel,
                       Relation pkrel, Oid indexOid, Oid parentConstr,
                       int numfks,
                       int16 *pkattnum, int16 *fkattnum, Oid *pfeqoperators,
                       Oid *ppeqoperators, Oid *ffeqoperators,
                       int numfkdelsetcols, int16 *fkdelsetcols,
                       bool old_check_ok,
                       Oid parentDelTrigger, Oid parentUpdTrigger,
                       bool with_period)
{
    Oid         deleteTriggerOid,
                updateTriggerOid;
 
    /*
     * Create the action triggers that enforce the constraint.
     */
    createForeignKeyActionTriggers(rel, RelationGetRelid(pkrel),
                                   fkconstraint,
                                   parentConstr, indexOid,
                                   parentDelTrigger, parentUpdTrigger,
                                   &deleteTriggerOid, &updateTriggerOid);
 
    /*
     * If the referenced table is partitioned, recurse on ourselves to handle
     * each partition.  We need one pg_constraint row created for each
     * partition in addition to the pg_constraint row for the parent table.
     */
    if (pkrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        PartitionDesc pd = RelationGetPartitionDesc(pkrel, true);
 
        for (int i = 0; i < pd->nparts; i++)
        {
            Relation    partRel;
            AttrMap    *map;
            AttrNumber *mapped_pkattnum;
            Oid         partIndexId;
            ObjectAddress address;
 
            partRel = table_open(pd->oids[i], ShareRowExclusiveLock);
 
            /*
             * Map the attribute numbers in the referenced side of the FK
             * definition to match the partition's column layout.
             */
            map = build_attrmap_by_name_if_req(RelationGetDescr(partRel),
                                               RelationGetDescr(pkrel),
                                               false);
            if (map)
            {
                mapped_pkattnum = palloc(sizeof(AttrNumber) * numfks);
                for (int j = 0; j < numfks; j++)
                    mapped_pkattnum[j] = map->attnums[pkattnum[j] - 1];
            }
            else
                mapped_pkattnum = pkattnum;
 
            /* Determine the index to use at this level */
            partIndexId = index_get_partition(partRel, indexOid);
            if (!OidIsValid(partIndexId))
                elog(ERROR, "index for %u not found in partition %s",
                     indexOid, RelationGetRelationName(partRel));
 
            /* Create entry at this level ... */
            address = addFkConstraint(addFkReferencedSide,
                                      fkconstraint->conname, fkconstraint, rel,
                                      partRel, partIndexId, parentConstr,
                                      numfks, mapped_pkattnum,
                                      fkattnum, pfeqoperators, ppeqoperators,
                                      ffeqoperators, numfkdelsetcols,
                                      fkdelsetcols, true, with_period);
            /* ... and recurse to our children */
            addFkRecurseReferenced(fkconstraint, rel, partRel,
                                   partIndexId, address.objectId, numfks,
                                   mapped_pkattnum, fkattnum,
                                   pfeqoperators, ppeqoperators, ffeqoperators,
                                   numfkdelsetcols, fkdelsetcols,
                                   old_check_ok,
                                   deleteTriggerOid, updateTriggerOid,
                                   with_period);
 
            /* Done -- clean up (but keep the lock) */
            table_close(partRel, NoLock);
            if (map)
            {
                pfree(mapped_pkattnum);
                free_attrmap(map);
            }
        }
    }
}
 
/*
 * addFkRecurseReferencing
 *      Recursive helper for the referencing side of foreign key creation,
 *      which creates the check triggers and recurses
 *
 * If the referencing relation is a plain relation, create the necessary check
 * triggers that implement the constraint, and set up for Phase 3 constraint
 * verification.  If the referencing relation is a partitioned table, then
 * we create a pg_constraint row for it and recurse on this routine for each
 * partition.
 *
 * We assume that the referenced relation is locked against concurrent
 * deletions.  If it's a partitioned relation, every partition must be so
 * locked.
 *
 * wqueue: the ALTER TABLE work queue; NULL when not running as part
 *      of an ALTER TABLE sequence.
 * fkconstraint: the constraint being added
 * rel: the referencing relation; might be a partition, if recursing
 * pkrel: the root referenced relation
 * indexOid: the OID of the index (on pkrel) implementing this constraint
 * parentConstr: the OID of the parent constraint (there is always one)
 * numfks: the number of columns in the foreign key
 * pkattnum: the attnum array of referenced attributes
 * fkattnum: the attnum array of referencing attributes
 * pf/pp/ffeqoperators: OID array of operators between columns
 * numfkdelsetcols: the number of columns in the ON DELETE SET NULL/DEFAULT
 *      (...) clause
 * fkdelsetcols: the attnum array of the columns in the ON DELETE SET
 *      NULL/DEFAULT clause
 * old_check_ok: true if this constraint replaces an existing one that
 *      was already validated (thus this one doesn't need validation)
 * lockmode: the lockmode to acquire on partitions when recursing
 * parentInsTrigger and parentUpdTrigger: when being recursively called on
 *      a partition, the OIDs of the parent check triggers for INSERT and
 *      UPDATE respectively.
 * with_period: true if this is a temporal FK
 */
static void
addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
                        Relation pkrel, Oid indexOid, Oid parentConstr,
                        int numfks, int16 *pkattnum, int16 *fkattnum,
                        Oid *pfeqoperators, Oid *ppeqoperators, Oid *ffeqoperators,
                        int numfkdelsetcols, int16 *fkdelsetcols,
                        bool old_check_ok, LOCKMODE lockmode,
                        Oid parentInsTrigger, Oid parentUpdTrigger,
                        bool with_period)
{
    Oid         insertTriggerOid,
                updateTriggerOid;
 
    Assert(OidIsValid(parentConstr));
 
    if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("foreign key constraints are not supported on foreign tables")));
 
    /*
     * Add the check triggers to it and, if necessary, schedule it to be
     * checked in Phase 3.
     *
     * If the relation is partitioned, drill down to do it to its partitions.
     */
    createForeignKeyCheckTriggers(RelationGetRelid(rel),
                                  RelationGetRelid(pkrel),
                                  fkconstraint,
                                  parentConstr,
                                  indexOid,
                                  parentInsTrigger, parentUpdTrigger,
                                  &insertTriggerOid, &updateTriggerOid);
 
    if (rel->rd_rel->relkind == RELKIND_RELATION)
    {
        /*
         * Tell Phase 3 to check that the constraint is satisfied by existing
         * rows. We can skip this during table creation, when requested
         * explicitly by specifying NOT VALID in an ADD FOREIGN KEY command,
         * and when we're recreating a constraint following a SET DATA TYPE
         * operation that did not impugn its validity.
         */
        if (wqueue && !old_check_ok && !fkconstraint->skip_validation)
        {
            NewConstraint *newcon;
            AlteredTableInfo *tab;
 
            tab = ATGetQueueEntry(wqueue, rel);
 
            newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
            newcon->name = get_constraint_name(parentConstr);
            newcon->contype = CONSTR_FOREIGN;
            newcon->refrelid = RelationGetRelid(pkrel);
            newcon->refindid = indexOid;
            newcon->conid = parentConstr;
            newcon->conwithperiod = fkconstraint->fk_with_period;
            newcon->qual = (Node *) fkconstraint;
 
            tab->constraints = lappend(tab->constraints, newcon);
        }
    }
    else if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        PartitionDesc pd = RelationGetPartitionDesc(rel, true);
        Relation    trigrel;
 
        /*
         * Triggers of the foreign keys will be manipulated a bunch of times
         * in the loop below.  To avoid repeatedly opening/closing the trigger
         * catalog relation, we open it here and pass it to the subroutines
         * called below.
         */
        trigrel = table_open(TriggerRelationId, RowExclusiveLock);
 
        /*
         * Recurse to take appropriate action on each partition; either we
         * find an existing constraint to reparent to ours, or we create a new
         * one.
         */
        for (int i = 0; i < pd->nparts; i++)
        {
            Oid         partitionId = pd->oids[i];
            Relation    partition = table_open(partitionId, lockmode);
            List       *partFKs;
            AttrMap    *attmap;
            AttrNumber  mapped_fkattnum[INDEX_MAX_KEYS];
            bool        attached;
            ObjectAddress address;
            ListCell   *cell;
 
            CheckAlterTableIsSafe(partition);
 
            attmap = build_attrmap_by_name(RelationGetDescr(partition),
                                           RelationGetDescr(rel),
                                           false);
            for (int j = 0; j < numfks; j++)
                mapped_fkattnum[j] = attmap->attnums[fkattnum[j] - 1];
 
            /* Check whether an existing constraint can be repurposed */
            partFKs = copyObject(RelationGetFKeyList(partition));
            attached = false;
            foreach(cell, partFKs)
            {
                ForeignKeyCacheInfo *fk;
 
                fk = lfirst_node(ForeignKeyCacheInfo, cell);
                if (tryAttachPartitionForeignKey(fk,
                                                 partitionId,
                                                 parentConstr,
                                                 numfks,
                                                 mapped_fkattnum,
                                                 pkattnum,
                                                 pfeqoperators,
                                                 insertTriggerOid,
                                                 updateTriggerOid,
                                                 trigrel))
                {
                    attached = true;
                    break;
                }
            }
            if (attached)
            {
                table_close(partition, NoLock);
                continue;
            }
 
            /*
             * No luck finding a good constraint to reuse; create our own.
             */
            address = addFkConstraint(addFkReferencingSide,
                                      fkconstraint->conname, fkconstraint,
                                      partition, pkrel, indexOid, parentConstr,
                                      numfks, pkattnum,
                                      mapped_fkattnum, pfeqoperators,
                                      ppeqoperators, ffeqoperators,
                                      numfkdelsetcols, fkdelsetcols, true,
                                      with_period);
 
            /* call ourselves to finalize the creation and we're done */
            addFkRecurseReferencing(wqueue, fkconstraint, partition, pkrel,
                                    indexOid,
                                    address.objectId,
                                    numfks,
                                    pkattnum,
                                    mapped_fkattnum,
                                    pfeqoperators,
                                    ppeqoperators,
                                    ffeqoperators,
                                    numfkdelsetcols,
                                    fkdelsetcols,
                                    old_check_ok,
                                    lockmode,
                                    insertTriggerOid,
                                    updateTriggerOid,
                                    with_period);
 
            table_close(partition, NoLock);
        }
 
        table_close(trigrel, RowExclusiveLock);
    }
}
 
/*
 * CloneForeignKeyConstraints
 *      Clone foreign keys from a partitioned table to a newly acquired
 *      partition.
 *
 * partitionRel is a partition of parentRel, so we can be certain that it has
 * the same columns with the same datatypes.  The columns may be in different
 * order, though.
 *
 * wqueue must be passed to set up phase 3 constraint checking, unless the
 * referencing-side partition is known to be empty (such as in CREATE TABLE /
 * PARTITION OF).
 */
static void
CloneForeignKeyConstraints(List **wqueue, Relation parentRel,
                           Relation partitionRel)
{
    /* This only works for declarative partitioning */
    Assert(parentRel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
    /*
     * Clone constraints for which the parent is on the referenced side.
     */
    CloneFkReferenced(parentRel, partitionRel);
 
    /*
     * Now clone constraints where the parent is on the referencing side.
     */
    CloneFkReferencing(wqueue, parentRel, partitionRel);
}
 
/*
 * CloneFkReferenced
 *      Subroutine for CloneForeignKeyConstraints
 *
 * Find all the FKs that have the parent relation on the referenced side;
 * clone those constraints to the given partition.  This is to be called
 * when the partition is being created or attached.
 *
 * This ignores self-referencing FKs; those are handled by CloneFkReferencing.
 *
 * This recurses to partitions, if the relation being attached is partitioned.
 * Recursion is done by calling addFkRecurseReferenced.
 */
static void
CloneFkReferenced(Relation parentRel, Relation partitionRel)
{
    Relation    pg_constraint;
    AttrMap    *attmap;
    ListCell   *cell;
    SysScanDesc scan;
    ScanKeyData key[2];
    HeapTuple   tuple;
    List       *clone = NIL;
    Relation    trigrel;
 
    /*
     * Search for any constraints where this partition's parent is in the
     * referenced side.  However, we must not clone any constraint whose
     * parent constraint is also going to be cloned, to avoid duplicates.  So
     * do it in two steps: first construct the list of constraints to clone,
     * then go over that list cloning those whose parents are not in the list.
     * (We must not rely on the parent being seen first, since the catalog
     * scan could return children first.)
     */
    pg_constraint = table_open(ConstraintRelationId, RowShareLock);
    ScanKeyInit(&key[0],
                Anum_pg_constraint_confrelid, BTEqualStrategyNumber,
                F_OIDEQ, ObjectIdGetDatum(RelationGetRelid(parentRel)));
    ScanKeyInit(&key[1],
                Anum_pg_constraint_contype, BTEqualStrategyNumber,
                F_CHAREQ, CharGetDatum(CONSTRAINT_FOREIGN));
    /* This is a seqscan, as we don't have a usable index ... */
    scan = systable_beginscan(pg_constraint, InvalidOid, true,
                              NULL, 2, key);
    while ((tuple = systable_getnext(scan)) != NULL)
    {
        Form_pg_constraint constrForm = (Form_pg_constraint) GETSTRUCT(tuple);
 
        clone = lappend_oid(clone, constrForm->oid);
    }
    systable_endscan(scan);
    table_close(pg_constraint, RowShareLock);
 
    /*
     * Triggers of the foreign keys will be manipulated a bunch of times in
     * the loop below.  To avoid repeatedly opening/closing the trigger
     * catalog relation, we open it here and pass it to the subroutines called
     * below.
     */
    trigrel = table_open(TriggerRelationId, RowExclusiveLock);
 
    attmap = build_attrmap_by_name(RelationGetDescr(partitionRel),
                                   RelationGetDescr(parentRel),
                                   false);
    foreach(cell, clone)
    {
        Oid         constrOid = lfirst_oid(cell);
        Form_pg_constraint constrForm;
        Relation    fkRel;
        Oid         indexOid;
        Oid         partIndexId;
        int         numfks;
        AttrNumber  conkey[INDEX_MAX_KEYS];
        AttrNumber  mapped_confkey[INDEX_MAX_KEYS];
        AttrNumber  confkey[INDEX_MAX_KEYS];
        Oid         conpfeqop[INDEX_MAX_KEYS];
        Oid         conppeqop[INDEX_MAX_KEYS];
        Oid         conffeqop[INDEX_MAX_KEYS];
        int         numfkdelsetcols;
        AttrNumber  confdelsetcols[INDEX_MAX_KEYS];
        Constraint *fkconstraint;
        ObjectAddress address;
        Oid         deleteTriggerOid,
                    updateTriggerOid;
 
        tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constrOid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for constraint %u", constrOid);
        constrForm = (Form_pg_constraint) GETSTRUCT(tuple);
 
        /*
         * As explained above: don't try to clone a constraint for which we're
         * going to clone the parent.
         */
        if (list_member_oid(clone, constrForm->conparentid))
        {
            ReleaseSysCache(tuple);
            continue;
        }
 
        /*
         * Don't clone self-referencing foreign keys, which can be in the
         * partitioned table or in the partition-to-be.
         */
        if (constrForm->conrelid == RelationGetRelid(parentRel) ||
            constrForm->conrelid == RelationGetRelid(partitionRel))
        {
            ReleaseSysCache(tuple);
            continue;
        }
 
        /*
         * Because we're only expanding the key space at the referenced side,
         * we don't need to prevent any operation in the referencing table, so
         * AccessShareLock suffices (assumes that dropping the constraint
         * acquires AccessExclusiveLock).
         */
        fkRel = table_open(constrForm->conrelid, AccessShareLock);
 
        indexOid = constrForm->conindid;
        DeconstructFkConstraintRow(tuple,
                                   &numfks,
                                   conkey,
                                   confkey,
                                   conpfeqop,
                                   conppeqop,
                                   conffeqop,
                                   &numfkdelsetcols,
                                   confdelsetcols);
 
        for (int i = 0; i < numfks; i++)
            mapped_confkey[i] = attmap->attnums[confkey[i] - 1];
 
        fkconstraint = makeNode(Constraint);
        fkconstraint->contype = CONSTRAINT_FOREIGN;
        fkconstraint->conname = NameStr(constrForm->conname);
        fkconstraint->deferrable = constrForm->condeferrable;
        fkconstraint->initdeferred = constrForm->condeferred;
        fkconstraint->location = -1;
        fkconstraint->pktable = NULL;
        /* ->fk_attrs determined below */
        fkconstraint->pk_attrs = NIL;
        fkconstraint->fk_matchtype = constrForm->confmatchtype;
        fkconstraint->fk_upd_action = constrForm->confupdtype;
        fkconstraint->fk_del_action = constrForm->confdeltype;
        fkconstraint->fk_del_set_cols = NIL;
        fkconstraint->old_conpfeqop = NIL;
        fkconstraint->old_pktable_oid = InvalidOid;
        fkconstraint->skip_validation = false;
        fkconstraint->initially_valid = true;
 
        /* set up colnames that are used to generate the constraint name */
        for (int i = 0; i < numfks; i++)
        {
            Form_pg_attribute att;
 
            att = TupleDescAttr(RelationGetDescr(fkRel),
                                conkey[i] - 1);
            fkconstraint->fk_attrs = lappend(fkconstraint->fk_attrs,
                                             makeString(NameStr(att->attname)));
        }
 
        /*
         * Add the new foreign key constraint pointing to the new partition.
         * Because this new partition appears in the referenced side of the
         * constraint, we don't need to set up for Phase 3 check.
         */
        partIndexId = index_get_partition(partitionRel, indexOid);
        if (!OidIsValid(partIndexId))
            elog(ERROR, "index for %u not found in partition %s",
                 indexOid, RelationGetRelationName(partitionRel));
 
        /*
         * Get the "action" triggers belonging to the constraint to pass as
         * parent OIDs for similar triggers that will be created on the
         * partition in addFkRecurseReferenced().
         */
        GetForeignKeyActionTriggers(trigrel, constrOid,
                                    constrForm->confrelid, constrForm->conrelid,
                                    &deleteTriggerOid, &updateTriggerOid);
 
        /* Add this constraint ... */
        address = addFkConstraint(addFkReferencedSide,
                                  fkconstraint->conname, fkconstraint, fkRel,
                                  partitionRel, partIndexId, constrOid,
                                  numfks, mapped_confkey,
                                  conkey, conpfeqop, conppeqop, conffeqop,
                                  numfkdelsetcols, confdelsetcols, false,
                                  constrForm->conperiod);
        /* ... and recurse */
        addFkRecurseReferenced(fkconstraint,
                               fkRel,
                               partitionRel,
                               partIndexId,
                               address.objectId,
                               numfks,
                               mapped_confkey,
                               conkey,
                               conpfeqop,
                               conppeqop,
                               conffeqop,
                               numfkdelsetcols,
                               confdelsetcols,
                               true,
                               deleteTriggerOid,
                               updateTriggerOid,
                               constrForm->conperiod);
 
        table_close(fkRel, NoLock);
        ReleaseSysCache(tuple);
    }
 
    table_close(trigrel, RowExclusiveLock);
}
 
/*
 * CloneFkReferencing
 *      Subroutine for CloneForeignKeyConstraints
 *
 * For each FK constraint of the parent relation in the given list, find an
 * equivalent constraint in its partition relation that can be reparented;
 * if one cannot be found, create a new constraint in the partition as its
 * child.
 *
 * If wqueue is given, it is used to set up phase-3 verification for each
 * cloned constraint; omit it if such verification is not needed
 * (example: the partition is being created anew).
 */
static void
CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
{
    AttrMap    *attmap;
    List       *partFKs;
    List       *clone = NIL;
    ListCell   *cell;
    Relation    trigrel;
 
    /* obtain a list of constraints that we need to clone */
    foreach(cell, RelationGetFKeyList(parentRel))
    {
        ForeignKeyCacheInfo *fk = lfirst(cell);
 
        /*
         * Refuse to attach a table as partition that this partitioned table
         * already has a foreign key to.  This isn't useful schema, which is
         * proven by the fact that there have been no user complaints that
         * it's already impossible to achieve this in the opposite direction,
         * i.e., creating a foreign key that references a partition.  This
         * restriction allows us to dodge some complexities around
         * pg_constraint and pg_trigger row creations that would be needed
         * during ATTACH/DETACH for this kind of relationship.
         */
        if (fk->confrelid == RelationGetRelid(partRel))
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot attach table \"%s\" as a partition because it is referenced by foreign key \"%s\"",
                            RelationGetRelationName(partRel),
                            get_constraint_name(fk->conoid))));
 
        clone = lappend_oid(clone, fk->conoid);
    }
 
    /*
     * Silently do nothing if there's nothing to do.  In particular, this
     * avoids throwing a spurious error for foreign tables.
     */
    if (clone == NIL)
        return;
 
    if (partRel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("foreign key constraints are not supported on foreign tables")));
 
    /*
     * Triggers of the foreign keys will be manipulated a bunch of times in
     * the loop below.  To avoid repeatedly opening/closing the trigger
     * catalog relation, we open it here and pass it to the subroutines called
     * below.
     */
    trigrel = table_open(TriggerRelationId, RowExclusiveLock);
 
    /*
     * The constraint key may differ, if the columns in the partition are
     * different.  This map is used to convert them.
     */
    attmap = build_attrmap_by_name(RelationGetDescr(partRel),
                                   RelationGetDescr(parentRel),
                                   false);
 
    partFKs = copyObject(RelationGetFKeyList(partRel));
 
    foreach(cell, clone)
    {
        Oid         parentConstrOid = lfirst_oid(cell);
        Form_pg_constraint constrForm;
        Relation    pkrel;
        HeapTuple   tuple;
        int         numfks;
        AttrNumber  conkey[INDEX_MAX_KEYS];
        AttrNumber  mapped_conkey[INDEX_MAX_KEYS];
        AttrNumber  confkey[INDEX_MAX_KEYS];
        Oid         conpfeqop[INDEX_MAX_KEYS];
        Oid         conppeqop[INDEX_MAX_KEYS];
        Oid         conffeqop[INDEX_MAX_KEYS];
        int         numfkdelsetcols;
        AttrNumber  confdelsetcols[INDEX_MAX_KEYS];
        Constraint *fkconstraint;
        bool        attached;
        Oid         indexOid;
        ObjectAddress address;
        ListCell   *lc;
        Oid         insertTriggerOid,
                    updateTriggerOid;
        bool        with_period;
 
        tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(parentConstrOid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for constraint %u",
                 parentConstrOid);
        constrForm = (Form_pg_constraint) GETSTRUCT(tuple);
 
        /* Don't clone constraints whose parents are being cloned */
        if (list_member_oid(clone, constrForm->conparentid))
        {
            ReleaseSysCache(tuple);
            continue;
        }
 
        /*
         * Need to prevent concurrent deletions.  If pkrel is a partitioned
         * relation, that means to lock all partitions.
         */
        pkrel = table_open(constrForm->confrelid, ShareRowExclusiveLock);
        if (pkrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
            (void) find_all_inheritors(RelationGetRelid(pkrel),
                                       ShareRowExclusiveLock, NULL);
 
        DeconstructFkConstraintRow(tuple, &numfks, conkey, confkey,
                                   conpfeqop, conppeqop, conffeqop,
                                   &numfkdelsetcols, confdelsetcols);
        for (int i = 0; i < numfks; i++)
            mapped_conkey[i] = attmap->attnums[conkey[i] - 1];
 
        /*
         * Get the "check" triggers belonging to the constraint to pass as
         * parent OIDs for similar triggers that will be created on the
         * partition in addFkRecurseReferencing().  They are also passed to
         * tryAttachPartitionForeignKey() below to simply assign as parents to
         * the partition's existing "check" triggers, that is, if the
         * corresponding constraints is deemed attachable to the parent
         * constraint.
         */
        GetForeignKeyCheckTriggers(trigrel, constrForm->oid,
                                   constrForm->confrelid, constrForm->conrelid,
                                   &insertTriggerOid, &updateTriggerOid);
 
        /*
         * Before creating a new constraint, see whether any existing FKs are
         * fit for the purpose.  If one is, attach the parent constraint to
         * it, and don't clone anything.  This way we avoid the expensive
         * verification step and don't end up with a duplicate FK, and we
         * don't need to recurse to partitions for this constraint.
         */
        attached = false;
        foreach(lc, partFKs)
        {
            ForeignKeyCacheInfo *fk = lfirst_node(ForeignKeyCacheInfo, lc);
 
            if (tryAttachPartitionForeignKey(fk,
                                             RelationGetRelid(partRel),
                                             parentConstrOid,
                                             numfks,
                                             mapped_conkey,
                                             confkey,
                                             conpfeqop,
                                             insertTriggerOid,
                                             updateTriggerOid,
                                             trigrel))
            {
                attached = true;
                table_close(pkrel, NoLock);
                break;
            }
        }
        if (attached)
        {
            ReleaseSysCache(tuple);
            continue;
        }
 
        /* No dice.  Set up to create our own constraint */
        fkconstraint = makeNode(Constraint);
        fkconstraint->contype = CONSTRAINT_FOREIGN;
        /* ->conname determined below */
        fkconstraint->deferrable = constrForm->condeferrable;
        fkconstraint->initdeferred = constrForm->condeferred;
        fkconstraint->location = -1;
        fkconstraint->pktable = NULL;
        /* ->fk_attrs determined below */
        fkconstraint->pk_attrs = NIL;
        fkconstraint->fk_matchtype = constrForm->confmatchtype;
        fkconstraint->fk_upd_action = constrForm->confupdtype;
        fkconstraint->fk_del_action = constrForm->confdeltype;
        fkconstraint->fk_del_set_cols = NIL;
        fkconstraint->old_conpfeqop = NIL;
        fkconstraint->old_pktable_oid = InvalidOid;
        fkconstraint->skip_validation = false;
        fkconstraint->initially_valid = constrForm->convalidated;
        for (int i = 0; i < numfks; i++)
        {
            Form_pg_attribute att;
 
            att = TupleDescAttr(RelationGetDescr(partRel),
                                mapped_conkey[i] - 1);
            fkconstraint->fk_attrs = lappend(fkconstraint->fk_attrs,
                                             makeString(NameStr(att->attname)));
        }
 
        indexOid = constrForm->conindid;
        with_period = constrForm->conperiod;
 
        /* Create the pg_constraint entry at this level */
        address = addFkConstraint(addFkReferencingSide,
                                  NameStr(constrForm->conname), fkconstraint,
                                  partRel, pkrel, indexOid, parentConstrOid,
                                  numfks, confkey,
                                  mapped_conkey, conpfeqop,
                                  conppeqop, conffeqop,
                                  numfkdelsetcols, confdelsetcols,
                                  false, with_period);
 
        /* Done with the cloned constraint's tuple */
        ReleaseSysCache(tuple);
 
        /* Create the check triggers, and recurse to partitions, if any */
        addFkRecurseReferencing(wqueue,
                                fkconstraint,
                                partRel,
                                pkrel,
                                indexOid,
                                address.objectId,
                                numfks,
                                confkey,
                                mapped_conkey,
                                conpfeqop,
                                conppeqop,
                                conffeqop,
                                numfkdelsetcols,
                                confdelsetcols,
                                false,  /* no old check exists */
                                AccessExclusiveLock,
                                insertTriggerOid,
                                updateTriggerOid,
                                with_period);
        table_close(pkrel, NoLock);
    }
 
    table_close(trigrel, RowExclusiveLock);
}
 
/*
 * When the parent of a partition receives [the referencing side of] a foreign
 * key, we must propagate that foreign key to the partition.  However, the
 * partition might already have an equivalent foreign key; this routine
 * compares the given ForeignKeyCacheInfo (in the partition) to the FK defined
 * by the other parameters.  If they are equivalent, create the link between
 * the two constraints and return true.
 *
 * If the given FK does not match the one defined by rest of the params,
 * return false.
 */
static bool
tryAttachPartitionForeignKey(ForeignKeyCacheInfo *fk,
                             Oid partRelid,
                             Oid parentConstrOid,
                             int numfks,
                             AttrNumber *mapped_conkey,
                             AttrNumber *confkey,
                             Oid *conpfeqop,
                             Oid parentInsTrigger,
                             Oid parentUpdTrigger,
                             Relation trigrel)
{
    HeapTuple   parentConstrTup;
    Form_pg_constraint parentConstr;
    HeapTuple   partcontup;
    Form_pg_constraint partConstr;
    ScanKeyData key;
    SysScanDesc scan;
    HeapTuple   trigtup;
    Oid         insertTriggerOid,
                updateTriggerOid;
 
    parentConstrTup = SearchSysCache1(CONSTROID,
                                      ObjectIdGetDatum(parentConstrOid));
    if (!HeapTupleIsValid(parentConstrTup))
        elog(ERROR, "cache lookup failed for constraint %u", parentConstrOid);
    parentConstr = (Form_pg_constraint) GETSTRUCT(parentConstrTup);
 
    /*
     * Do some quick & easy initial checks.  If any of these fail, we cannot
     * use this constraint.
     */
    if (fk->confrelid != parentConstr->confrelid || fk->nkeys != numfks)
    {
        ReleaseSysCache(parentConstrTup);
        return false;
    }
    for (int i = 0; i < numfks; i++)
    {
        if (fk->conkey[i] != mapped_conkey[i] ||
            fk->confkey[i] != confkey[i] ||
            fk->conpfeqop[i] != conpfeqop[i])
        {
            ReleaseSysCache(parentConstrTup);
            return false;
        }
    }
 
    /*
     * Looks good so far; do some more extensive checks.  Presumably the check
     * for 'convalidated' could be dropped, since we don't really care about
     * that, but let's be careful for now.
     */
    partcontup = SearchSysCache1(CONSTROID,
                                 ObjectIdGetDatum(fk->conoid));
    if (!HeapTupleIsValid(partcontup))
        elog(ERROR, "cache lookup failed for constraint %u", fk->conoid);
    partConstr = (Form_pg_constraint) GETSTRUCT(partcontup);
    if (OidIsValid(partConstr->conparentid) ||
        !partConstr->convalidated ||
        partConstr->condeferrable != parentConstr->condeferrable ||
        partConstr->condeferred != parentConstr->condeferred ||
        partConstr->confupdtype != parentConstr->confupdtype ||
        partConstr->confdeltype != parentConstr->confdeltype ||
        partConstr->confmatchtype != parentConstr->confmatchtype)
    {
        ReleaseSysCache(parentConstrTup);
        ReleaseSysCache(partcontup);
        return false;
    }
 
    ReleaseSysCache(partcontup);
    ReleaseSysCache(parentConstrTup);
 
    /*
     * Looks good!  Attach this constraint.  The action triggers in the new
     * partition become redundant -- the parent table already has equivalent
     * ones, and those will be able to reach the partition.  Remove the ones
     * in the partition.  We identify them because they have our constraint
     * OID, as well as being on the referenced rel.
     */
    ScanKeyInit(&key,
                Anum_pg_trigger_tgconstraint,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(fk->conoid));
    scan = systable_beginscan(trigrel, TriggerConstraintIndexId, true,
                              NULL, 1, &key);
    while ((trigtup = systable_getnext(scan)) != NULL)
    {
        Form_pg_trigger trgform = (Form_pg_trigger) GETSTRUCT(trigtup);
        ObjectAddress trigger;
 
        if (trgform->tgconstrrelid != fk->conrelid)
            continue;
        if (trgform->tgrelid != fk->confrelid)
            continue;
 
        /*
         * The constraint is originally set up to contain this trigger as an
         * implementation object, so there's a dependency record that links
         * the two; however, since the trigger is no longer needed, we remove
         * the dependency link in order to be able to drop the trigger while
         * keeping the constraint intact.
         */
        deleteDependencyRecordsFor(TriggerRelationId,
                                   trgform->oid,
                                   false);
        /* make dependency deletion visible to performDeletion */
        CommandCounterIncrement();
        ObjectAddressSet(trigger, TriggerRelationId,
                         trgform->oid);
        performDeletion(&trigger, DROP_RESTRICT, 0);
        /* make trigger drop visible, in case the loop iterates */
        CommandCounterIncrement();
    }
 
    systable_endscan(scan);
 
    ConstraintSetParentConstraint(fk->conoid, parentConstrOid, partRelid);
 
    /*
     * Like the constraint, attach partition's "check" triggers to the
     * corresponding parent triggers.
     */
    GetForeignKeyCheckTriggers(trigrel,
                               fk->conoid, fk->confrelid, fk->conrelid,
                               &insertTriggerOid, &updateTriggerOid);
    Assert(OidIsValid(insertTriggerOid) && OidIsValid(parentInsTrigger));
    TriggerSetParentTrigger(trigrel, insertTriggerOid, parentInsTrigger,
                            partRelid);
    Assert(OidIsValid(updateTriggerOid) && OidIsValid(parentUpdTrigger));
    TriggerSetParentTrigger(trigrel, updateTriggerOid, parentUpdTrigger,
                            partRelid);
 
    /*
     * If the referenced table is partitioned, then the partition we're
     * attaching now has extra pg_constraint rows and action triggers that are
     * no longer needed.  Remove those.
     */
    if (get_rel_relkind(fk->confrelid) == RELKIND_PARTITIONED_TABLE)
    {
        Relation    pg_constraint = table_open(ConstraintRelationId, RowShareLock);
        ObjectAddresses *objs;
        HeapTuple   consttup;
 
        ScanKeyInit(&key,
                    Anum_pg_constraint_conrelid,
                    BTEqualStrategyNumber, F_OIDEQ,
                    ObjectIdGetDatum(fk->conrelid));
 
        scan = systable_beginscan(pg_constraint,
                                  ConstraintRelidTypidNameIndexId,
                                  true, NULL, 1, &key);
        objs = new_object_addresses();
        while ((consttup = systable_getnext(scan)) != NULL)
        {
            Form_pg_constraint conform = (Form_pg_constraint) GETSTRUCT(consttup);
 
            if (conform->conparentid != fk->conoid)
                continue;
            else
            {
                ObjectAddress addr;
                SysScanDesc scan2;
                ScanKeyData key2;
                int         n PG_USED_FOR_ASSERTS_ONLY;
 
                ObjectAddressSet(addr, ConstraintRelationId, conform->oid);
                add_exact_object_address(&addr, objs);
 
                /*
                 * First we must delete the dependency record that binds the
                 * constraint records together.
                 */
                n = deleteDependencyRecordsForSpecific(ConstraintRelationId,
                                                       conform->oid,
                                                       DEPENDENCY_INTERNAL,
                                                       ConstraintRelationId,
                                                       fk->conoid);
                Assert(n == 1); /* actually only one is expected */
 
                /*
                 * Now search for the triggers for this constraint and set
                 * them up for deletion too
                 */
                ScanKeyInit(&key2,
                            Anum_pg_trigger_tgconstraint,
                            BTEqualStrategyNumber, F_OIDEQ,
                            ObjectIdGetDatum(conform->oid));
                scan2 = systable_beginscan(trigrel, TriggerConstraintIndexId,
                                           true, NULL, 1, &key2);
                while ((trigtup = systable_getnext(scan2)) != NULL)
                {
                    ObjectAddressSet(addr, TriggerRelationId,
                                     ((Form_pg_trigger) GETSTRUCT(trigtup))->oid);
                    add_exact_object_address(&addr, objs);
                }
                systable_endscan(scan2);
            }
        }
        /* make the dependency deletions visible */
        CommandCounterIncrement();
        performMultipleDeletions(objs, DROP_RESTRICT,
                                 PERFORM_DELETION_INTERNAL);
        systable_endscan(scan);
 
        table_close(pg_constraint, RowShareLock);
    }
 
    CommandCounterIncrement();
    return true;
}
 
/*
 * GetForeignKeyActionTriggers
 *      Returns delete and update "action" triggers of the given relation
 *      belonging to the given constraint
 */
static void
GetForeignKeyActionTriggers(Relation trigrel,
                            Oid conoid, Oid confrelid, Oid conrelid,
                            Oid *deleteTriggerOid,
                            Oid *updateTriggerOid)
{
    ScanKeyData key;
    SysScanDesc scan;
    HeapTuple   trigtup;
 
    *deleteTriggerOid = *updateTriggerOid = InvalidOid;
    ScanKeyInit(&key,
                Anum_pg_trigger_tgconstraint,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(conoid));
 
    scan = systable_beginscan(trigrel, TriggerConstraintIndexId, true,
                              NULL, 1, &key);
    while ((trigtup = systable_getnext(scan)) != NULL)
    {
        Form_pg_trigger trgform = (Form_pg_trigger) GETSTRUCT(trigtup);
 
        if (trgform->tgconstrrelid != conrelid)
            continue;
        if (trgform->tgrelid != confrelid)
            continue;
        /* Only ever look at "action" triggers on the PK side. */
        if (RI_FKey_trigger_type(trgform->tgfoid) != RI_TRIGGER_PK)
            continue;
        if (TRIGGER_FOR_DELETE(trgform->tgtype))
        {
            Assert(*deleteTriggerOid == InvalidOid);
            *deleteTriggerOid = trgform->oid;
        }
        else if (TRIGGER_FOR_UPDATE(trgform->tgtype))
        {
            Assert(*updateTriggerOid == InvalidOid);
            *updateTriggerOid = trgform->oid;
        }
#ifndef USE_ASSERT_CHECKING
        /* In an assert-enabled build, continue looking to find duplicates */
        if (OidIsValid(*deleteTriggerOid) && OidIsValid(*updateTriggerOid))
            break;
#endif
    }
 
    if (!OidIsValid(*deleteTriggerOid))
        elog(ERROR, "could not find ON DELETE action trigger of foreign key constraint %u",
             conoid);
    if (!OidIsValid(*updateTriggerOid))
        elog(ERROR, "could not find ON UPDATE action trigger of foreign key constraint %u",
             conoid);
 
    systable_endscan(scan);
}
 
/*
 * GetForeignKeyCheckTriggers
 *      Returns insert and update "check" triggers of the given relation
 *      belonging to the given constraint
 */
static void
GetForeignKeyCheckTriggers(Relation trigrel,
                           Oid conoid, Oid confrelid, Oid conrelid,
                           Oid *insertTriggerOid,
                           Oid *updateTriggerOid)
{
    ScanKeyData key;
    SysScanDesc scan;
    HeapTuple   trigtup;
 
    *insertTriggerOid = *updateTriggerOid = InvalidOid;
    ScanKeyInit(&key,
                Anum_pg_trigger_tgconstraint,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(conoid));
 
    scan = systable_beginscan(trigrel, TriggerConstraintIndexId, true,
                              NULL, 1, &key);
    while ((trigtup = systable_getnext(scan)) != NULL)
    {
        Form_pg_trigger trgform = (Form_pg_trigger) GETSTRUCT(trigtup);
 
        if (trgform->tgconstrrelid != confrelid)
            continue;
        if (trgform->tgrelid != conrelid)
            continue;
        /* Only ever look at "check" triggers on the FK side. */
        if (RI_FKey_trigger_type(trgform->tgfoid) != RI_TRIGGER_FK)
            continue;
        if (TRIGGER_FOR_INSERT(trgform->tgtype))
        {
            Assert(*insertTriggerOid == InvalidOid);
            *insertTriggerOid = trgform->oid;
        }
        else if (TRIGGER_FOR_UPDATE(trgform->tgtype))
        {
            Assert(*updateTriggerOid == InvalidOid);
            *updateTriggerOid = trgform->oid;
        }
#ifndef USE_ASSERT_CHECKING
        /* In an assert-enabled build, continue looking to find duplicates. */
        if (OidIsValid(*insertTriggerOid) && OidIsValid(*updateTriggerOid))
            break;
#endif
    }
 
    if (!OidIsValid(*insertTriggerOid))
        elog(ERROR, "could not find ON INSERT check triggers of foreign key constraint %u",
             conoid);
    if (!OidIsValid(*updateTriggerOid))
        elog(ERROR, "could not find ON UPDATE check triggers of foreign key constraint %u",
             conoid);
 
    systable_endscan(scan);
}
 
/*
 * ALTER TABLE ALTER CONSTRAINT
 *
 * Update the attributes of a constraint.
 *
 * Currently only works for Foreign Key constraints.
 *
 * If the constraint is modified, returns its address; otherwise, return
 * InvalidObjectAddress.
 */
static ObjectAddress
ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd, bool recurse,
                      bool recursing, LOCKMODE lockmode)
{
    Constraint *cmdcon;
    Relation    conrel;
    Relation    tgrel;
    SysScanDesc scan;
    ScanKeyData skey[3];
    HeapTuple   contuple;
    Form_pg_constraint currcon;
    ObjectAddress address;
    List       *otherrelids = NIL;
    ListCell   *lc;
 
    cmdcon = castNode(Constraint, cmd->def);
 
    conrel = table_open(ConstraintRelationId, RowExclusiveLock);
    tgrel = table_open(TriggerRelationId, RowExclusiveLock);
 
    /*
     * Find and check the target constraint
     */
    ScanKeyInit(&skey[0],
                Anum_pg_constraint_conrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(rel)));
    ScanKeyInit(&skey[1],
                Anum_pg_constraint_contypid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(InvalidOid));
    ScanKeyInit(&skey[2],
                Anum_pg_constraint_conname,
                BTEqualStrategyNumber, F_NAMEEQ,
                CStringGetDatum(cmdcon->conname));
    scan = systable_beginscan(conrel, ConstraintRelidTypidNameIndexId,
                              true, NULL, 3, skey);
 
    /* There can be at most one matching row */
    if (!HeapTupleIsValid(contuple = systable_getnext(scan)))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("constraint \"%s\" of relation \"%s\" does not exist",
                        cmdcon->conname, RelationGetRelationName(rel))));
 
    currcon = (Form_pg_constraint) GETSTRUCT(contuple);
    if (currcon->contype != CONSTRAINT_FOREIGN)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("constraint \"%s\" of relation \"%s\" is not a foreign key constraint",
                        cmdcon->conname, RelationGetRelationName(rel))));
 
    /*
     * If it's not the topmost constraint, raise an error.
     *
     * Altering a non-topmost constraint leaves some triggers untouched, since
     * they are not directly connected to this constraint; also, pg_dump would
     * ignore the deferrability status of the individual constraint, since it
     * only dumps topmost constraints.  Avoid these problems by refusing this
     * operation and telling the user to alter the parent constraint instead.
     */
    if (OidIsValid(currcon->conparentid))
    {
        HeapTuple   tp;
        Oid         parent = currcon->conparentid;
        char       *ancestorname = NULL;
        char       *ancestortable = NULL;
 
        /* Loop to find the topmost constraint */
        while (HeapTupleIsValid(tp = SearchSysCache1(CONSTROID, ObjectIdGetDatum(parent))))
        {
            Form_pg_constraint contup = (Form_pg_constraint) GETSTRUCT(tp);
 
            /* If no parent, this is the constraint we want */
            if (!OidIsValid(contup->conparentid))
            {
                ancestorname = pstrdup(NameStr(contup->conname));
                ancestortable = get_rel_name(contup->conrelid);
                ReleaseSysCache(tp);
                break;
            }
 
            parent = contup->conparentid;
            ReleaseSysCache(tp);
        }
 
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cannot alter constraint \"%s\" on relation \"%s\"",
                        cmdcon->conname, RelationGetRelationName(rel)),
                 ancestorname && ancestortable ?
                 errdetail("Constraint \"%s\" is derived from constraint \"%s\" of relation \"%s\".",
                           cmdcon->conname, ancestorname, ancestortable) : 0,
                 errhint("You may alter the constraint it derives from instead.")));
    }
 
    /*
     * Do the actual catalog work.  We can skip changing if already in the
     * desired state, but not if a partitioned table: partitions need to be
     * processed regardless, in case they had the constraint locally changed.
     */
    address = InvalidObjectAddress;
    if (currcon->condeferrable != cmdcon->deferrable ||
        currcon->condeferred != cmdcon->initdeferred ||
        rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        if (ATExecAlterConstrRecurse(cmdcon, conrel, tgrel, rel, contuple,
                                     &otherrelids, lockmode))
            ObjectAddressSet(address, ConstraintRelationId, currcon->oid);
    }
 
    /*
     * ATExecAlterConstrRecurse already invalidated relcache for the relations
     * having the constraint itself; here we also invalidate for relations
     * that have any triggers that are part of the constraint.
     */
    foreach(lc, otherrelids)
        CacheInvalidateRelcacheByRelid(lfirst_oid(lc));
 
    systable_endscan(scan);
 
    table_close(tgrel, RowExclusiveLock);
    table_close(conrel, RowExclusiveLock);
 
    return address;
}
 
/*
 * Recursive subroutine of ATExecAlterConstraint.  Returns true if the
 * constraint is altered.
 *
 * *otherrelids is appended OIDs of relations containing affected triggers.
 *
 * Note that we must recurse even when the values are correct, in case
 * indirect descendants have had their constraints altered locally.
 * (This could be avoided if we forbade altering constraints in partitions
 * but existing releases don't do that.)
 */
static bool
ATExecAlterConstrRecurse(Constraint *cmdcon, Relation conrel, Relation tgrel,
                         Relation rel, HeapTuple contuple, List **otherrelids,
                         LOCKMODE lockmode)
{
    Form_pg_constraint currcon;
    Oid         conoid;
    Oid         refrelid;
    bool        changed = false;
 
    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();
 
    currcon = (Form_pg_constraint) GETSTRUCT(contuple);
    conoid = currcon->oid;
    refrelid = currcon->confrelid;
 
    /*
     * Update pg_constraint with the flags from cmdcon.
     *
     * If called to modify a constraint that's already in the desired state,
     * silently do nothing.
     */
    if (currcon->condeferrable != cmdcon->deferrable ||
        currcon->condeferred != cmdcon->initdeferred)
    {
        HeapTuple   copyTuple;
        Form_pg_constraint copy_con;
        HeapTuple   tgtuple;
        ScanKeyData tgkey;
        SysScanDesc tgscan;
 
        copyTuple = heap_copytuple(contuple);
        copy_con = (Form_pg_constraint) GETSTRUCT(copyTuple);
        copy_con->condeferrable = cmdcon->deferrable;
        copy_con->condeferred = cmdcon->initdeferred;
        CatalogTupleUpdate(conrel, &copyTuple->t_self, copyTuple);
 
        InvokeObjectPostAlterHook(ConstraintRelationId,
                                  conoid, 0);
 
        heap_freetuple(copyTuple);
        changed = true;
 
        /* Make new constraint flags visible to others */
        CacheInvalidateRelcache(rel);
 
        /*
         * Now we need to update the multiple entries in pg_trigger that
         * implement the constraint.
         */
        ScanKeyInit(&tgkey,
                    Anum_pg_trigger_tgconstraint,
                    BTEqualStrategyNumber, F_OIDEQ,
                    ObjectIdGetDatum(conoid));
        tgscan = systable_beginscan(tgrel, TriggerConstraintIndexId, true,
                                    NULL, 1, &tgkey);
        while (HeapTupleIsValid(tgtuple = systable_getnext(tgscan)))
        {
            Form_pg_trigger tgform = (Form_pg_trigger) GETSTRUCT(tgtuple);
            Form_pg_trigger copy_tg;
            HeapTuple   tgCopyTuple;
 
            /*
             * Remember OIDs of other relation(s) involved in FK constraint.
             * (Note: it's likely that we could skip forcing a relcache inval
             * for other rels that don't have a trigger whose properties
             * change, but let's be conservative.)
             */
            if (tgform->tgrelid != RelationGetRelid(rel))
                *otherrelids = list_append_unique_oid(*otherrelids,
                                                      tgform->tgrelid);
 
            /*
             * Update deferrability of RI_FKey_noaction_del,
             * RI_FKey_noaction_upd, RI_FKey_check_ins and RI_FKey_check_upd
             * triggers, but not others; see createForeignKeyActionTriggers
             * and CreateFKCheckTrigger.
             */
            if (tgform->tgfoid != F_RI_FKEY_NOACTION_DEL &&
                tgform->tgfoid != F_RI_FKEY_NOACTION_UPD &&
                tgform->tgfoid != F_RI_FKEY_CHECK_INS &&
                tgform->tgfoid != F_RI_FKEY_CHECK_UPD)
                continue;
 
            tgCopyTuple = heap_copytuple(tgtuple);
            copy_tg = (Form_pg_trigger) GETSTRUCT(tgCopyTuple);
 
            copy_tg->tgdeferrable = cmdcon->deferrable;
            copy_tg->tginitdeferred = cmdcon->initdeferred;
            CatalogTupleUpdate(tgrel, &tgCopyTuple->t_self, tgCopyTuple);
 
            InvokeObjectPostAlterHook(TriggerRelationId, tgform->oid, 0);
 
            heap_freetuple(tgCopyTuple);
        }
 
        systable_endscan(tgscan);
    }
 
    /*
     * If the table at either end of the constraint is partitioned, we need to
     * recurse and handle every constraint that is a child of this one.
     *
     * (This assumes that the recurse flag is forcibly set for partitioned
     * tables, and not set for legacy inheritance, though we don't check for
     * that here.)
     */
    if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ||
        get_rel_relkind(refrelid) == RELKIND_PARTITIONED_TABLE)
    {
        ScanKeyData pkey;
        SysScanDesc pscan;
        HeapTuple   childtup;
 
        ScanKeyInit(&pkey,
                    Anum_pg_constraint_conparentid,
                    BTEqualStrategyNumber, F_OIDEQ,
                    ObjectIdGetDatum(conoid));
 
        pscan = systable_beginscan(conrel, ConstraintParentIndexId,
                                   true, NULL, 1, &pkey);
 
        while (HeapTupleIsValid(childtup = systable_getnext(pscan)))
        {
            Form_pg_constraint childcon = (Form_pg_constraint) GETSTRUCT(childtup);
            Relation    childrel;
 
            childrel = table_open(childcon->conrelid, lockmode);
            ATExecAlterConstrRecurse(cmdcon, conrel, tgrel, childrel, childtup,
                                     otherrelids, lockmode);
            table_close(childrel, NoLock);
        }
 
        systable_endscan(pscan);
    }
 
    return changed;
}
 
/*
 * ALTER TABLE VALIDATE CONSTRAINT
 *
 * XXX The reason we handle recursion here rather than at Phase 1 is because
 * there's no good way to skip recursing when handling foreign keys: there is
 * no need to lock children in that case, yet we wouldn't be able to avoid
 * doing so at that level.
 *
 * Return value is the address of the validated constraint.  If the constraint
 * was already validated, InvalidObjectAddress is returned.
 */
static ObjectAddress
ATExecValidateConstraint(List **wqueue, Relation rel, char *constrName,
                         bool recurse, bool recursing, LOCKMODE lockmode)
{
    Relation    conrel;
    SysScanDesc scan;
    ScanKeyData skey[3];
    HeapTuple   tuple;
    Form_pg_constraint con;
    ObjectAddress address;
 
    conrel = table_open(ConstraintRelationId, RowExclusiveLock);
 
    /*
     * Find and check the target constraint
     */
    ScanKeyInit(&skey[0],
                Anum_pg_constraint_conrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(rel)));
    ScanKeyInit(&skey[1],
                Anum_pg_constraint_contypid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(InvalidOid));
    ScanKeyInit(&skey[2],
                Anum_pg_constraint_conname,
                BTEqualStrategyNumber, F_NAMEEQ,
                CStringGetDatum(constrName));
    scan = systable_beginscan(conrel, ConstraintRelidTypidNameIndexId,
                              true, NULL, 3, skey);
 
    /* There can be at most one matching row */
    if (!HeapTupleIsValid(tuple = systable_getnext(scan)))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("constraint \"%s\" of relation \"%s\" does not exist",
                        constrName, RelationGetRelationName(rel))));
 
    con = (Form_pg_constraint) GETSTRUCT(tuple);
    if (con->contype != CONSTRAINT_FOREIGN &&
        con->contype != CONSTRAINT_CHECK)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("constraint \"%s\" of relation \"%s\" is not a foreign key or check constraint",
                        constrName, RelationGetRelationName(rel))));
 
    if (!con->convalidated)
    {
        AlteredTableInfo *tab;
        HeapTuple   copyTuple;
        Form_pg_constraint copy_con;
 
        if (con->contype == CONSTRAINT_FOREIGN)
        {
            NewConstraint *newcon;
            Constraint *fkconstraint;
 
            /* Queue validation for phase 3 */
            fkconstraint = makeNode(Constraint);
            /* for now this is all we need */
            fkconstraint->conname = constrName;
 
            newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
            newcon->name = constrName;
            newcon->contype = CONSTR_FOREIGN;
            newcon->refrelid = con->confrelid;
            newcon->refindid = con->conindid;
            newcon->conid = con->oid;
            newcon->qual = (Node *) fkconstraint;
 
            /* Find or create work queue entry for this table */
            tab = ATGetQueueEntry(wqueue, rel);
            tab->constraints = lappend(tab->constraints, newcon);
 
            /*
             * We disallow creating invalid foreign keys to or from
             * partitioned tables, so ignoring the recursion bit is okay.
             */
        }
        else if (con->contype == CONSTRAINT_CHECK)
        {
            List       *children = NIL;
            ListCell   *child;
            NewConstraint *newcon;
            Datum       val;
            char       *conbin;
 
            /*
             * If we're recursing, the parent has already done this, so skip
             * it.  Also, if the constraint is a NO INHERIT constraint, we
             * shouldn't try to look for it in the children.
             */
            if (!recursing && !con->connoinherit)
                children = find_all_inheritors(RelationGetRelid(rel),
                                               lockmode, NULL);
 
            /*
             * For CHECK constraints, we must ensure that we only mark the
             * constraint as validated on the parent if it's already validated
             * on the children.
             *
             * We recurse before validating on the parent, to reduce risk of
             * deadlocks.
             */
            foreach(child, children)
            {
                Oid         childoid = lfirst_oid(child);
                Relation    childrel;
 
                if (childoid == RelationGetRelid(rel))
                    continue;
 
                /*
                 * If we are told not to recurse, there had better not be any
                 * child tables, because we can't mark the constraint on the
                 * parent valid unless it is valid for all child tables.
                 */
                if (!recurse)
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                             errmsg("constraint must be validated on child tables too")));
 
                /* find_all_inheritors already got lock */
                childrel = table_open(childoid, NoLock);
 
                ATExecValidateConstraint(wqueue, childrel, constrName, false,
                                         true, lockmode);
                table_close(childrel, NoLock);
            }
 
            /* Queue validation for phase 3 */
            newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
            newcon->name = constrName;
            newcon->contype = CONSTR_CHECK;
            newcon->refrelid = InvalidOid;
            newcon->refindid = InvalidOid;
            newcon->conid = con->oid;
 
            val = SysCacheGetAttrNotNull(CONSTROID, tuple,
                                         Anum_pg_constraint_conbin);
            conbin = TextDatumGetCString(val);
            newcon->qual = (Node *) stringToNode(conbin);
 
            /* Find or create work queue entry for this table */
            tab = ATGetQueueEntry(wqueue, rel);
            tab->constraints = lappend(tab->constraints, newcon);
 
            /*
             * Invalidate relcache so that others see the new validated
             * constraint.
             */
            CacheInvalidateRelcache(rel);
        }
 
        /*
         * Now update the catalog, while we have the door open.
         */
        copyTuple = heap_copytuple(tuple);
        copy_con = (Form_pg_constraint) GETSTRUCT(copyTuple);
        copy_con->convalidated = true;
        CatalogTupleUpdate(conrel, &copyTuple->t_self, copyTuple);
 
        InvokeObjectPostAlterHook(ConstraintRelationId, con->oid, 0);
 
        heap_freetuple(copyTuple);
 
        ObjectAddressSet(address, ConstraintRelationId, con->oid);
    }
    else
        address = InvalidObjectAddress; /* already validated */
 
    systable_endscan(scan);
 
    table_close(conrel, RowExclusiveLock);
 
    return address;
}
 
 
/*
 * transformColumnNameList - transform list of column names
 *
 * Lookup each name and return its attnum and, optionally, type OID
 *
 * Note: the name of this function suggests that it's general-purpose,
 * but actually it's only used to look up names appearing in foreign-key
 * clauses.  The error messages would need work to use it in other cases,
 * and perhaps the validity checks as well.
 */
static int
transformColumnNameList(Oid relId, List *colList,
                        int16 *attnums, Oid *atttypids)
{
    ListCell   *l;
    int         attnum;
 
    attnum = 0;
    foreach(l, colList)
    {
        char       *attname = strVal(lfirst(l));
        HeapTuple   atttuple;
        Form_pg_attribute attform;
 
        atttuple = SearchSysCacheAttName(relId, attname);
        if (!HeapTupleIsValid(atttuple))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" referenced in foreign key constraint does not exist",
                            attname)));
        attform = (Form_pg_attribute) GETSTRUCT(atttuple);
        if (attform->attnum < 0)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("system columns cannot be used in foreign keys")));
        if (attnum >= INDEX_MAX_KEYS)
            ereport(ERROR,
                    (errcode(ERRCODE_TOO_MANY_COLUMNS),
                     errmsg("cannot have more than %d keys in a foreign key",
                            INDEX_MAX_KEYS)));
        attnums[attnum] = attform->attnum;
        if (atttypids != NULL)
            atttypids[attnum] = attform->atttypid;
        ReleaseSysCache(atttuple);
        attnum++;
    }
 
    return attnum;
}
 
/*
 * transformFkeyGetPrimaryKey -
 *
 *  Look up the names, attnums, and types of the primary key attributes
 *  for the pkrel.  Also return the index OID and index opclasses of the
 *  index supporting the primary key.  Also return whether the index has
 *  WITHOUT OVERLAPS.
 *
 *  All parameters except pkrel are output parameters.  Also, the function
 *  return value is the number of attributes in the primary key.
 *
 *  Used when the column list in the REFERENCES specification is omitted.
 */
static int
transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
                           List **attnamelist,
                           int16 *attnums, Oid *atttypids,
                           Oid *opclasses, bool *pk_has_without_overlaps)
{
    List       *indexoidlist;
    ListCell   *indexoidscan;
    HeapTuple   indexTuple = NULL;
    Form_pg_index indexStruct = NULL;
    Datum       indclassDatum;
    oidvector  *indclass;
    int         i;
 
    /*
     * Get the list of index OIDs for the table from the relcache, and look up
     * each one in the pg_index syscache until we find one marked primary key
     * (hopefully there isn't more than one such).  Insist it's valid, too.
     */
    *indexOid = InvalidOid;
 
    indexoidlist = RelationGetIndexList(pkrel);
 
    foreach(indexoidscan, indexoidlist)
    {
        Oid         indexoid = lfirst_oid(indexoidscan);
 
        indexTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexoid));
        if (!HeapTupleIsValid(indexTuple))
            elog(ERROR, "cache lookup failed for index %u", indexoid);
        indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);
        if (indexStruct->indisprimary && indexStruct->indisvalid)
        {
            /*
             * Refuse to use a deferrable primary key.  This is per SQL spec,
             * and there would be a lot of interesting semantic problems if we
             * tried to allow it.
             */
            if (!indexStruct->indimmediate)
                ereport(ERROR,
                        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                         errmsg("cannot use a deferrable primary key for referenced table \"%s\"",
                                RelationGetRelationName(pkrel))));
 
            *indexOid = indexoid;
            break;
        }
        ReleaseSysCache(indexTuple);
    }
 
    list_free(indexoidlist);
 
    /*
     * Check that we found it
     */
    if (!OidIsValid(*indexOid))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("there is no primary key for referenced table \"%s\"",
                        RelationGetRelationName(pkrel))));
 
    /* Must get indclass the hard way */
    indclassDatum = SysCacheGetAttrNotNull(INDEXRELID, indexTuple,
                                           Anum_pg_index_indclass);
    indclass = (oidvector *) DatumGetPointer(indclassDatum);
 
    /*
     * Now build the list of PK attributes from the indkey definition (we
     * assume a primary key cannot have expressional elements)
     */
    *attnamelist = NIL;
    for (i = 0; i < indexStruct->indnkeyatts; i++)
    {
        int         pkattno = indexStruct->indkey.values[i];
 
        attnums[i] = pkattno;
        atttypids[i] = attnumTypeId(pkrel, pkattno);
        opclasses[i] = indclass->values[i];
        *attnamelist = lappend(*attnamelist,
                               makeString(pstrdup(NameStr(*attnumAttName(pkrel, pkattno)))));
    }
 
    *pk_has_without_overlaps = indexStruct->indisexclusion;
 
    ReleaseSysCache(indexTuple);
 
    return i;
}
 
/*
 * transformFkeyCheckAttrs -
 *
 *  Validate that the 'attnums' columns in the 'pkrel' relation are valid to
 *  reference as part of a foreign key constraint.
 *
 *  Returns the OID of the unique index supporting the constraint and
 *  populates the caller-provided 'opclasses' array with the opclasses
 *  associated with the index columns.  Also sets whether the index
 *  uses WITHOUT OVERLAPS.
 *
 *  Raises an ERROR on validation failure.
 */
static Oid
transformFkeyCheckAttrs(Relation pkrel,
                        int numattrs, int16 *attnums,
                        bool with_period, Oid *opclasses,
                        bool *pk_has_without_overlaps)
{
    Oid         indexoid = InvalidOid;
    bool        found = false;
    bool        found_deferrable = false;
    List       *indexoidlist;
    ListCell   *indexoidscan;
    int         i,
                j;
 
    /*
     * Reject duplicate appearances of columns in the referenced-columns list.
     * Such a case is forbidden by the SQL standard, and even if we thought it
     * useful to allow it, there would be ambiguity about how to match the
     * list to unique indexes (in particular, it'd be unclear which index
     * opclass goes with which FK column).
     */
    for (i = 0; i < numattrs; i++)
    {
        for (j = i + 1; j < numattrs; j++)
        {
            if (attnums[i] == attnums[j])
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_FOREIGN_KEY),
                         errmsg("foreign key referenced-columns list must not contain duplicates")));
        }
    }
 
    /*
     * Get the list of index OIDs for the table from the relcache, and look up
     * each one in the pg_index syscache, and match unique indexes to the list
     * of attnums we are given.
     */
    indexoidlist = RelationGetIndexList(pkrel);
 
    foreach(indexoidscan, indexoidlist)
    {
        HeapTuple   indexTuple;
        Form_pg_index indexStruct;
 
        indexoid = lfirst_oid(indexoidscan);
        indexTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexoid));
        if (!HeapTupleIsValid(indexTuple))
            elog(ERROR, "cache lookup failed for index %u", indexoid);
        indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);
 
        /*
         * Must have the right number of columns; must be unique (or if
         * temporal then exclusion instead) and not a partial index; forget it
         * if there are any expressions, too. Invalid indexes are out as well.
         */
        if (indexStruct->indnkeyatts == numattrs &&
            (with_period ? indexStruct->indisexclusion : indexStruct->indisunique) &&
            indexStruct->indisvalid &&
            heap_attisnull(indexTuple, Anum_pg_index_indpred, NULL) &&
            heap_attisnull(indexTuple, Anum_pg_index_indexprs, NULL))
        {
            Datum       indclassDatum;
            oidvector  *indclass;
 
            /* Must get indclass the hard way */
            indclassDatum = SysCacheGetAttrNotNull(INDEXRELID, indexTuple,
                                                   Anum_pg_index_indclass);
            indclass = (oidvector *) DatumGetPointer(indclassDatum);
 
            /*
             * The given attnum list may match the index columns in any order.
             * Check for a match, and extract the appropriate opclasses while
             * we're at it.
             *
             * We know that attnums[] is duplicate-free per the test at the
             * start of this function, and we checked above that the number of
             * index columns agrees, so if we find a match for each attnums[]
             * entry then we must have a one-to-one match in some order.
             */
            for (i = 0; i < numattrs; i++)
            {
                found = false;
                for (j = 0; j < numattrs; j++)
                {
                    if (attnums[i] == indexStruct->indkey.values[j])
                    {
                        opclasses[i] = indclass->values[j];
                        found = true;
                        break;
                    }
                }
                if (!found)
                    break;
            }
            /* The last attribute in the index must be the PERIOD FK part */
            if (found && with_period)
            {
                int16       periodattnum = attnums[numattrs - 1];
 
                found = (periodattnum == indexStruct->indkey.values[numattrs - 1]);
            }
 
            /*
             * Refuse to use a deferrable unique/primary key.  This is per SQL
             * spec, and there would be a lot of interesting semantic problems
             * if we tried to allow it.
             */
            if (found && !indexStruct->indimmediate)
            {
                /*
                 * Remember that we found an otherwise matching index, so that
                 * we can generate a more appropriate error message.
                 */
                found_deferrable = true;
                found = false;
            }
 
            /* We need to know whether the index has WITHOUT OVERLAPS */
            if (found)
                *pk_has_without_overlaps = indexStruct->indisexclusion;
        }
        ReleaseSysCache(indexTuple);
        if (found)
            break;
    }
 
    if (!found)
    {
        if (found_deferrable)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("cannot use a deferrable unique constraint for referenced table \"%s\"",
                            RelationGetRelationName(pkrel))));
        else
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FOREIGN_KEY),
                     errmsg("there is no unique constraint matching given keys for referenced table \"%s\"",
                            RelationGetRelationName(pkrel))));
    }
 
    list_free(indexoidlist);
 
    return indexoid;
}
 
/*
 * findFkeyCast -
 *
 *  Wrapper around find_coercion_pathway() for ATAddForeignKeyConstraint().
 *  Caller has equal regard for binary coercibility and for an exact match.
*/
static CoercionPathType
findFkeyCast(Oid targetTypeId, Oid sourceTypeId, Oid *funcid)
{
    CoercionPathType ret;
 
    if (targetTypeId == sourceTypeId)
    {
        ret = COERCION_PATH_RELABELTYPE;
        *funcid = InvalidOid;
    }
    else
    {
        ret = find_coercion_pathway(targetTypeId, sourceTypeId,
                                    COERCION_IMPLICIT, funcid);
        if (ret == COERCION_PATH_NONE)
            /* A previously-relied-upon cast is now gone. */
            elog(ERROR, "could not find cast from %u to %u",
                 sourceTypeId, targetTypeId);
    }
 
    return ret;
}
 
/*
 * Permissions checks on the referenced table for ADD FOREIGN KEY
 *
 * Note: we have already checked that the user owns the referencing table,
 * else we'd have failed much earlier; no additional checks are needed for it.
 */
static void
checkFkeyPermissions(Relation rel, int16 *attnums, int natts)
{
    Oid         roleid = GetUserId();
    AclResult   aclresult;
    int         i;
 
    /* Okay if we have relation-level REFERENCES permission */
    aclresult = pg_class_aclcheck(RelationGetRelid(rel), roleid,
                                  ACL_REFERENCES);
    if (aclresult == ACLCHECK_OK)
        return;
    /* Else we must have REFERENCES on each column */
    for (i = 0; i < natts; i++)
    {
        aclresult = pg_attribute_aclcheck(RelationGetRelid(rel), attnums[i],
                                          roleid, ACL_REFERENCES);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind),
                           RelationGetRelationName(rel));
    }
}
 
/*
 * Scan the existing rows in a table to verify they meet a proposed FK
 * constraint.
 *
 * Caller must have opened and locked both relations appropriately.
 */
static void
validateForeignKeyConstraint(char *conname,
                             Relation rel,
                             Relation pkrel,
                             Oid pkindOid,
                             Oid constraintOid,
                             bool hasperiod)
{
    TupleTableSlot *slot;
    TableScanDesc scan;
    Trigger     trig = {0};
    Snapshot    snapshot;
    MemoryContext oldcxt;
    MemoryContext perTupCxt;
 
    ereport(DEBUG1,
            (errmsg_internal("validating foreign key constraint \"%s\"", conname)));
 
    /*
     * Build a trigger call structure; we'll need it either way.
     */
    trig.tgoid = InvalidOid;
    trig.tgname = conname;
    trig.tgenabled = TRIGGER_FIRES_ON_ORIGIN;
    trig.tgisinternal = true;
    trig.tgconstrrelid = RelationGetRelid(pkrel);
    trig.tgconstrindid = pkindOid;
    trig.tgconstraint = constraintOid;
    trig.tgdeferrable = false;
    trig.tginitdeferred = false;
    /* we needn't fill in remaining fields */
 
    /*
     * See if we can do it with a single LEFT JOIN query.  A false result
     * indicates we must proceed with the fire-the-trigger method. We can't do
     * a LEFT JOIN for temporal FKs yet, but we can once we support temporal
     * left joins.
     */
    if (!hasperiod && RI_Initial_Check(&trig, rel, pkrel))
        return;
 
    /*
     * Scan through each tuple, calling RI_FKey_check_ins (insert trigger) as
     * if that tuple had just been inserted.  If any of those fail, it should
     * ereport(ERROR) and that's that.
     */
    snapshot = RegisterSnapshot(GetLatestSnapshot());
    slot = table_slot_create(rel, NULL);
    scan = table_beginscan(rel, snapshot, 0, NULL);
 
    perTupCxt = AllocSetContextCreate(CurrentMemoryContext,
                                      "validateForeignKeyConstraint",
                                      ALLOCSET_SMALL_SIZES);
    oldcxt = MemoryContextSwitchTo(perTupCxt);
 
    while (table_scan_getnextslot(scan, ForwardScanDirection, slot))
    {
        LOCAL_FCINFO(fcinfo, 0);
        TriggerData trigdata = {0};
 
        CHECK_FOR_INTERRUPTS();
 
        /*
         * Make a call to the trigger function
         *
         * No parameters are passed, but we do set a context
         */
        MemSet(fcinfo, 0, SizeForFunctionCallInfo(0));
 
        /*
         * We assume RI_FKey_check_ins won't look at flinfo...
         */
        trigdata.type = T_TriggerData;
        trigdata.tg_event = TRIGGER_EVENT_INSERT | TRIGGER_EVENT_ROW;
        trigdata.tg_relation = rel;
        trigdata.tg_trigtuple = ExecFetchSlotHeapTuple(slot, false, NULL);
        trigdata.tg_trigslot = slot;
        trigdata.tg_trigger = &trig;
 
        fcinfo->context = (Node *) &trigdata;
 
        RI_FKey_check_ins(fcinfo);
 
        MemoryContextReset(perTupCxt);
    }
 
    MemoryContextSwitchTo(oldcxt);
    MemoryContextDelete(perTupCxt);
    table_endscan(scan);
    UnregisterSnapshot(snapshot);
    ExecDropSingleTupleTableSlot(slot);
}
 
/*
 * CreateFKCheckTrigger
 *      Creates the insert (on_insert=true) or update "check" trigger that
 *      implements a given foreign key
 *
 * Returns the OID of the so created trigger.
 */
static Oid
CreateFKCheckTrigger(Oid myRelOid, Oid refRelOid, Constraint *fkconstraint,
                     Oid constraintOid, Oid indexOid, Oid parentTrigOid,
                     bool on_insert)
{
    ObjectAddress trigAddress;
    CreateTrigStmt *fk_trigger;
 
    /*
     * Note: for a self-referential FK (referencing and referenced tables are
     * the same), it is important that the ON UPDATE action fires before the
     * CHECK action, since both triggers will fire on the same row during an
     * UPDATE event; otherwise the CHECK trigger will be checking a non-final
     * state of the row.  Triggers fire in name order, so we ensure this by
     * using names like "RI_ConstraintTrigger_a_NNNN" for the action triggers
     * and "RI_ConstraintTrigger_c_NNNN" for the check triggers.
     */
    fk_trigger = makeNode(CreateTrigStmt);
    fk_trigger->replace = false;
    fk_trigger->isconstraint = true;
    fk_trigger->trigname = "RI_ConstraintTrigger_c";
    fk_trigger->relation = NULL;
 
    /* Either ON INSERT or ON UPDATE */
    if (on_insert)
    {
        fk_trigger->funcname = SystemFuncName("RI_FKey_check_ins");
        fk_trigger->events = TRIGGER_TYPE_INSERT;
    }
    else
    {
        fk_trigger->funcname = SystemFuncName("RI_FKey_check_upd");
        fk_trigger->events = TRIGGER_TYPE_UPDATE;
    }
 
    fk_trigger->args = NIL;
    fk_trigger->row = true;
    fk_trigger->timing = TRIGGER_TYPE_AFTER;
    fk_trigger->columns = NIL;
    fk_trigger->whenClause = NULL;
    fk_trigger->transitionRels = NIL;
    fk_trigger->deferrable = fkconstraint->deferrable;
    fk_trigger->initdeferred = fkconstraint->initdeferred;
    fk_trigger->constrrel = NULL;
 
    trigAddress = CreateTrigger(fk_trigger, NULL, myRelOid, refRelOid,
                                constraintOid, indexOid, InvalidOid,
                                parentTrigOid, NULL, true, false);
 
    /* Make changes-so-far visible */
    CommandCounterIncrement();
 
    return trigAddress.objectId;
}
 
/*
 * createForeignKeyActionTriggers
 *      Create the referenced-side "action" triggers that implement a foreign
 *      key.
 *
 * Returns the OIDs of the so created triggers in *deleteTrigOid and
 * *updateTrigOid.
 */
static void
createForeignKeyActionTriggers(Relation rel, Oid refRelOid, Constraint *fkconstraint,
                               Oid constraintOid, Oid indexOid,
                               Oid parentDelTrigger, Oid parentUpdTrigger,
                               Oid *deleteTrigOid, Oid *updateTrigOid)
{
    CreateTrigStmt *fk_trigger;
    ObjectAddress trigAddress;
 
    /*
     * Build and execute a CREATE CONSTRAINT TRIGGER statement for the ON
     * DELETE action on the referenced table.
     */
    fk_trigger = makeNode(CreateTrigStmt);
    fk_trigger->replace = false;
    fk_trigger->isconstraint = true;
    fk_trigger->trigname = "RI_ConstraintTrigger_a";
    fk_trigger->relation = NULL;
    fk_trigger->args = NIL;
    fk_trigger->row = true;
    fk_trigger->timing = TRIGGER_TYPE_AFTER;
    fk_trigger->events = TRIGGER_TYPE_DELETE;
    fk_trigger->columns = NIL;
    fk_trigger->whenClause = NULL;
    fk_trigger->transitionRels = NIL;
    fk_trigger->constrrel = NULL;
 
    switch (fkconstraint->fk_del_action)
    {
        case FKCONSTR_ACTION_NOACTION:
            fk_trigger->deferrable = fkconstraint->deferrable;
            fk_trigger->initdeferred = fkconstraint->initdeferred;
            fk_trigger->funcname = SystemFuncName("RI_FKey_noaction_del");
            break;
        case FKCONSTR_ACTION_RESTRICT:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_restrict_del");
            break;
        case FKCONSTR_ACTION_CASCADE:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_cascade_del");
            break;
        case FKCONSTR_ACTION_SETNULL:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_setnull_del");
            break;
        case FKCONSTR_ACTION_SETDEFAULT:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_setdefault_del");
            break;
        default:
            elog(ERROR, "unrecognized FK action type: %d",
                 (int) fkconstraint->fk_del_action);
            break;
    }
 
    trigAddress = CreateTrigger(fk_trigger, NULL, refRelOid,
                                RelationGetRelid(rel),
                                constraintOid, indexOid, InvalidOid,
                                parentDelTrigger, NULL, true, false);
    if (deleteTrigOid)
        *deleteTrigOid = trigAddress.objectId;
 
    /* Make changes-so-far visible */
    CommandCounterIncrement();
 
    /*
     * Build and execute a CREATE CONSTRAINT TRIGGER statement for the ON
     * UPDATE action on the referenced table.
     */
    fk_trigger = makeNode(CreateTrigStmt);
    fk_trigger->replace = false;
    fk_trigger->isconstraint = true;
    fk_trigger->trigname = "RI_ConstraintTrigger_a";
    fk_trigger->relation = NULL;
    fk_trigger->args = NIL;
    fk_trigger->row = true;
    fk_trigger->timing = TRIGGER_TYPE_AFTER;
    fk_trigger->events = TRIGGER_TYPE_UPDATE;
    fk_trigger->columns = NIL;
    fk_trigger->whenClause = NULL;
    fk_trigger->transitionRels = NIL;
    fk_trigger->constrrel = NULL;
 
    switch (fkconstraint->fk_upd_action)
    {
        case FKCONSTR_ACTION_NOACTION:
            fk_trigger->deferrable = fkconstraint->deferrable;
            fk_trigger->initdeferred = fkconstraint->initdeferred;
            fk_trigger->funcname = SystemFuncName("RI_FKey_noaction_upd");
            break;
        case FKCONSTR_ACTION_RESTRICT:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_restrict_upd");
            break;
        case FKCONSTR_ACTION_CASCADE:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_cascade_upd");
            break;
        case FKCONSTR_ACTION_SETNULL:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_setnull_upd");
            break;
        case FKCONSTR_ACTION_SETDEFAULT:
            fk_trigger->deferrable = false;
            fk_trigger->initdeferred = false;
            fk_trigger->funcname = SystemFuncName("RI_FKey_setdefault_upd");
            break;
        default:
            elog(ERROR, "unrecognized FK action type: %d",
                 (int) fkconstraint->fk_upd_action);
            break;
    }
 
    trigAddress = CreateTrigger(fk_trigger, NULL, refRelOid,
                                RelationGetRelid(rel),
                                constraintOid, indexOid, InvalidOid,
                                parentUpdTrigger, NULL, true, false);
    if (updateTrigOid)
        *updateTrigOid = trigAddress.objectId;
}
 
/*
 * createForeignKeyCheckTriggers
 *      Create the referencing-side "check" triggers that implement a foreign
 *      key.
 *
 * Returns the OIDs of the so created triggers in *insertTrigOid and
 * *updateTrigOid.
 */
static void
createForeignKeyCheckTriggers(Oid myRelOid, Oid refRelOid,
                              Constraint *fkconstraint, Oid constraintOid,
                              Oid indexOid,
                              Oid parentInsTrigger, Oid parentUpdTrigger,
                              Oid *insertTrigOid, Oid *updateTrigOid)
{
    *insertTrigOid = CreateFKCheckTrigger(myRelOid, refRelOid, fkconstraint,
                                          constraintOid, indexOid,
                                          parentInsTrigger, true);
    *updateTrigOid = CreateFKCheckTrigger(myRelOid, refRelOid, fkconstraint,
                                          constraintOid, indexOid,
                                          parentUpdTrigger, false);
}
 
/*
 * ALTER TABLE DROP CONSTRAINT
 *
 * Like DROP COLUMN, we can't use the normal ALTER TABLE recursion mechanism.
 */
static void
ATExecDropConstraint(Relation rel, const char *constrName,
                     DropBehavior behavior,
                     bool recurse, bool recursing,
                     bool missing_ok, LOCKMODE lockmode)
{
    List       *children;
    Relation    conrel;
    Form_pg_constraint con;
    SysScanDesc scan;
    ScanKeyData skey[3];
    HeapTuple   tuple;
    bool        found = false;
    bool        is_no_inherit_constraint = false;
    char        contype;
 
    /* At top level, permission check was done in ATPrepCmd, else do it */
    if (recursing)
        ATSimplePermissions(AT_DropConstraint, rel,
                            ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
 
    conrel = table_open(ConstraintRelationId, RowExclusiveLock);
 
    /*
     * Find and drop the target constraint
     */
    ScanKeyInit(&skey[0],
                Anum_pg_constraint_conrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(rel)));
    ScanKeyInit(&skey[1],
                Anum_pg_constraint_contypid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(InvalidOid));
    ScanKeyInit(&skey[2],
                Anum_pg_constraint_conname,
                BTEqualStrategyNumber, F_NAMEEQ,
                CStringGetDatum(constrName));
    scan = systable_beginscan(conrel, ConstraintRelidTypidNameIndexId,
                              true, NULL, 3, skey);
 
    /* There can be at most one matching row */
    if (HeapTupleIsValid(tuple = systable_getnext(scan)))
    {
        ObjectAddress conobj;
 
        con = (Form_pg_constraint) GETSTRUCT(tuple);
 
        /* Don't drop inherited constraints */
        if (con->coninhcount > 0 && !recursing)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("cannot drop inherited constraint \"%s\" of relation \"%s\"",
                            constrName, RelationGetRelationName(rel))));
 
        is_no_inherit_constraint = con->connoinherit;
        contype = con->contype;
 
        /*
         * If it's a foreign-key constraint, we'd better lock the referenced
         * table and check that that's not in use, just as we've already done
         * for the constrained table (else we might, eg, be dropping a trigger
         * that has unfired events).  But we can/must skip that in the
         * self-referential case.
         */
        if (contype == CONSTRAINT_FOREIGN &&
            con->confrelid != RelationGetRelid(rel))
        {
            Relation    frel;
 
            /* Must match lock taken by RemoveTriggerById: */
            frel = table_open(con->confrelid, AccessExclusiveLock);
            CheckAlterTableIsSafe(frel);
            table_close(frel, NoLock);
        }
 
        /*
         * Perform the actual constraint deletion
         */
        conobj.classId = ConstraintRelationId;
        conobj.objectId = con->oid;
        conobj.objectSubId = 0;
 
        performDeletion(&conobj, behavior, 0);
 
        found = true;
    }
 
    systable_endscan(scan);
 
    if (!found)
    {
        if (!missing_ok)
        {
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("constraint \"%s\" of relation \"%s\" does not exist",
                            constrName, RelationGetRelationName(rel))));
        }
        else
        {
            ereport(NOTICE,
                    (errmsg("constraint \"%s\" of relation \"%s\" does not exist, skipping",
                            constrName, RelationGetRelationName(rel))));
            table_close(conrel, RowExclusiveLock);
            return;
        }
    }
 
    /*
     * For partitioned tables, non-CHECK inherited constraints are dropped via
     * the dependency mechanism, so we're done here.
     */
    if (contype != CONSTRAINT_CHECK &&
        rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        table_close(conrel, RowExclusiveLock);
        return;
    }
 
    /*
     * Propagate to children as appropriate.  Unlike most other ALTER
     * routines, we have to do this one level of recursion at a time; we can't
     * use find_all_inheritors to do it in one pass.
     */
    if (!is_no_inherit_constraint)
        children = find_inheritance_children(RelationGetRelid(rel), lockmode);
    else
        children = NIL;
 
    foreach_oid(childrelid, children)
    {
        Relation    childrel;
        HeapTuple   copy_tuple;
 
        /* find_inheritance_children already got lock */
        childrel = table_open(childrelid, NoLock);
        CheckAlterTableIsSafe(childrel);
 
        ScanKeyInit(&skey[0],
                    Anum_pg_constraint_conrelid,
                    BTEqualStrategyNumber, F_OIDEQ,
                    ObjectIdGetDatum(childrelid));
        ScanKeyInit(&skey[1],
                    Anum_pg_constraint_contypid,
                    BTEqualStrategyNumber, F_OIDEQ,
                    ObjectIdGetDatum(InvalidOid));
        ScanKeyInit(&skey[2],
                    Anum_pg_constraint_conname,
                    BTEqualStrategyNumber, F_NAMEEQ,
                    CStringGetDatum(constrName));
        scan = systable_beginscan(conrel, ConstraintRelidTypidNameIndexId,
                                  true, NULL, 3, skey);
 
        /* There can be at most one matching row */
        if (!HeapTupleIsValid(tuple = systable_getnext(scan)))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("constraint \"%s\" of relation \"%s\" does not exist",
                            constrName,
                            RelationGetRelationName(childrel))));
 
        copy_tuple = heap_copytuple(tuple);
 
        systable_endscan(scan);
 
        con = (Form_pg_constraint) GETSTRUCT(copy_tuple);
 
        /* Right now only CHECK constraints can be inherited */
        if (con->contype != CONSTRAINT_CHECK)
            elog(ERROR, "inherited constraint is not a CHECK constraint");
 
        if (con->coninhcount <= 0)  /* shouldn't happen */
            elog(ERROR, "relation %u has non-inherited constraint \"%s\"",
                 childrelid, constrName);
 
        if (recurse)
        {
            /*
             * If the child constraint has other definition sources, just
             * decrement its inheritance count; if not, recurse to delete it.
             */
            if (con->coninhcount == 1 && !con->conislocal)
            {
                /* Time to delete this child constraint, too */
                ATExecDropConstraint(childrel, constrName, behavior,
                                     true, true,
                                     false, lockmode);
            }
            else
            {
                /* Child constraint must survive my deletion */
                con->coninhcount--;
                CatalogTupleUpdate(conrel, &copy_tuple->t_self, copy_tuple);
 
                /* Make update visible */
                CommandCounterIncrement();
            }
        }
        else
        {
            /*
             * If we were told to drop ONLY in this table (no recursion), we
             * need to mark the inheritors' constraints as locally defined
             * rather than inherited.
             */
            con->coninhcount--;
            con->conislocal = true;
 
            CatalogTupleUpdate(conrel, &copy_tuple->t_self, copy_tuple);
 
            /* Make update visible */
            CommandCounterIncrement();
        }
 
        heap_freetuple(copy_tuple);
 
        table_close(childrel, NoLock);
    }
 
    table_close(conrel, RowExclusiveLock);
}
 
/*
 * ALTER COLUMN TYPE
 *
 * Unlike other subcommand types, we do parse transformation for ALTER COLUMN
 * TYPE during phase 1 --- the AlterTableCmd passed in here is already
 * transformed (and must be, because we rely on some transformed fields).
 *
 * The point of this is that the execution of all ALTER COLUMN TYPEs for a
 * table will be done "in parallel" during phase 3, so all the USING
 * expressions should be parsed assuming the original column types.  Also,
 * this allows a USING expression to refer to a field that will be dropped.
 *
 * To make this work safely, AT_PASS_DROP then AT_PASS_ALTER_TYPE must be
 * the first two execution steps in phase 2; they must not see the effects
 * of any other subcommand types, since the USING expressions are parsed
 * against the unmodified table's state.
 */
static void
ATPrepAlterColumnType(List **wqueue,
                      AlteredTableInfo *tab, Relation rel,
                      bool recurse, bool recursing,
                      AlterTableCmd *cmd, LOCKMODE lockmode,
                      AlterTableUtilityContext *context)
{
    char       *colName = cmd->name;
    ColumnDef  *def = (ColumnDef *) cmd->def;
    TypeName   *typeName = def->typeName;
    Node       *transform = def->cooked_default;
    HeapTuple   tuple;
    Form_pg_attribute attTup;
    AttrNumber  attnum;
    Oid         targettype;
    int32       targettypmod;
    Oid         targetcollid;
    NewColumnValue *newval;
    ParseState *pstate = make_parsestate(NULL);
    AclResult   aclresult;
    bool        is_expr;
 
    if (rel->rd_rel->reloftype && !recursing)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot alter column type of typed table")));
 
    /* lookup the attribute so we can check inheritance status */
    tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
    attTup = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = attTup->attnum;
 
    /* Can't alter a system attribute */
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"",
                        colName)));
 
    /*
     * Cannot specify USING when altering type of a generated column, because
     * that would violate the generation expression.
     */
    if (attTup->attgenerated && def->cooked_default)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                 errmsg("cannot specify USING when altering type of generated column"),
                 errdetail("Column \"%s\" is a generated column.", colName)));
 
    /*
     * Don't alter inherited columns.  At outer level, there had better not be
     * any inherited definition; when recursing, we assume this was checked at
     * the parent level (see below).
     */
    if (attTup->attinhcount > 0 && !recursing)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot alter inherited column \"%s\"",
                        colName)));
 
    /* Don't alter columns used in the partition key */
    if (has_partition_attrs(rel,
                            bms_make_singleton(attnum - FirstLowInvalidHeapAttributeNumber),
                            &is_expr))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("cannot alter column \"%s\" because it is part of the partition key of relation \"%s\"",
                        colName, RelationGetRelationName(rel))));
 
    /* Look up the target type */
    typenameTypeIdAndMod(NULL, typeName, &targettype, &targettypmod);
 
    aclresult = object_aclcheck(TypeRelationId, targettype, GetUserId(), ACL_USAGE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error_type(aclresult, targettype);
 
    /* And the collation */
    targetcollid = GetColumnDefCollation(NULL, def, targettype);
 
    /* make sure datatype is legal for a column */
    CheckAttributeType(colName, targettype, targetcollid,
                       list_make1_oid(rel->rd_rel->reltype),
                       0);
 
    if (tab->relkind == RELKIND_RELATION ||
        tab->relkind == RELKIND_PARTITIONED_TABLE)
    {
        /*
         * Set up an expression to transform the old data value to the new
         * type. If a USING option was given, use the expression as
         * transformed by transformAlterTableStmt, else just take the old
         * value and try to coerce it.  We do this first so that type
         * incompatibility can be detected before we waste effort, and because
         * we need the expression to be parsed against the original table row
         * type.
         */
        if (!transform)
        {
            transform = (Node *) makeVar(1, attnum,
                                         attTup->atttypid, attTup->atttypmod,
                                         attTup->attcollation,
                                         0);
        }
 
        transform = coerce_to_target_type(pstate,
                                          transform, exprType(transform),
                                          targettype, targettypmod,
                                          COERCION_ASSIGNMENT,
                                          COERCE_IMPLICIT_CAST,
                                          -1);
        if (transform == NULL)
        {
            /* error text depends on whether USING was specified or not */
            if (def->cooked_default != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("result of USING clause for column \"%s\""
                                " cannot be cast automatically to type %s",
                                colName, format_type_be(targettype)),
                         errhint("You might need to add an explicit cast.")));
            else
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("column \"%s\" cannot be cast automatically to type %s",
                                colName, format_type_be(targettype)),
                         !attTup->attgenerated ?
                /* translator: USING is SQL, don't translate it */
                         errhint("You might need to specify \"USING %s::%s\".",
                                 quote_identifier(colName),
                                 format_type_with_typemod(targettype,
                                                          targettypmod)) : 0));
        }
 
        /* Fix collations after all else */
        assign_expr_collations(pstate, transform);
 
        /* Plan the expr now so we can accurately assess the need to rewrite. */
        transform = (Node *) expression_planner((Expr *) transform);
 
        /*
         * Add a work queue item to make ATRewriteTable update the column
         * contents.
         */
        newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
        newval->attnum = attnum;
        newval->expr = (Expr *) transform;
        newval->is_generated = false;
 
        tab->newvals = lappend(tab->newvals, newval);
        if (ATColumnChangeRequiresRewrite(transform, attnum))
            tab->rewrite |= AT_REWRITE_COLUMN_REWRITE;
    }
    else if (transform)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a table",
                        RelationGetRelationName(rel))));
 
    if (!RELKIND_HAS_STORAGE(tab->relkind))
    {
        /*
         * For relations without storage, do this check now.  Regular tables
         * will check it later when the table is being rewritten.
         */
        find_composite_type_dependencies(rel->rd_rel->reltype, rel, NULL);
    }
 
    ReleaseSysCache(tuple);
 
    /*
     * Recurse manually by queueing a new command for each child, if
     * necessary. We cannot apply ATSimpleRecursion here because we need to
     * remap attribute numbers in the USING expression, if any.
     *
     * If we are told not to recurse, there had better not be any child
     * tables; else the alter would put them out of step.
     */
    if (recurse)
    {
        Oid         relid = RelationGetRelid(rel);
        List       *child_oids,
                   *child_numparents;
        ListCell   *lo,
                   *li;
 
        child_oids = find_all_inheritors(relid, lockmode,
                                         &child_numparents);
 
        /*
         * find_all_inheritors does the recursive search of the inheritance
         * hierarchy, so all we have to do is process all of the relids in the
         * list that it returns.
         */
        forboth(lo, child_oids, li, child_numparents)
        {
            Oid         childrelid = lfirst_oid(lo);
            int         numparents = lfirst_int(li);
            Relation    childrel;
            HeapTuple   childtuple;
            Form_pg_attribute childattTup;
 
            if (childrelid == relid)
                continue;
 
            /* find_all_inheritors already got lock */
            childrel = relation_open(childrelid, NoLock);
            CheckAlterTableIsSafe(childrel);
 
            /*
             * Verify that the child doesn't have any inherited definitions of
             * this column that came from outside this inheritance hierarchy.
             * (renameatt makes a similar test, though in a different way
             * because of its different recursion mechanism.)
             */
            childtuple = SearchSysCacheAttName(RelationGetRelid(childrel),
                                               colName);
            if (!HeapTupleIsValid(childtuple))
                ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                colName, RelationGetRelationName(childrel))));
            childattTup = (Form_pg_attribute) GETSTRUCT(childtuple);
 
            if (childattTup->attinhcount > numparents)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("cannot alter inherited column \"%s\" of relation \"%s\"",
                                colName, RelationGetRelationName(childrel))));
 
            ReleaseSysCache(childtuple);
 
            /*
             * Remap the attribute numbers.  If no USING expression was
             * specified, there is no need for this step.
             */
            if (def->cooked_default)
            {
                AttrMap    *attmap;
                bool        found_whole_row;
 
                /* create a copy to scribble on */
                cmd = copyObject(cmd);
 
                attmap = build_attrmap_by_name(RelationGetDescr(childrel),
                                               RelationGetDescr(rel),
                                               false);
                ((ColumnDef *) cmd->def)->cooked_default =
                    map_variable_attnos(def->cooked_default,
                                        1, 0,
                                        attmap,
                                        InvalidOid, &found_whole_row);
                if (found_whole_row)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot convert whole-row table reference"),
                             errdetail("USING expression contains a whole-row table reference.")));
                pfree(attmap);
            }
            ATPrepCmd(wqueue, childrel, cmd, false, true, lockmode, context);
            relation_close(childrel, NoLock);
        }
    }
    else if (!recursing &&
             find_inheritance_children(RelationGetRelid(rel), NoLock) != NIL)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("type of inherited column \"%s\" must be changed in child tables too",
                        colName)));
 
    if (tab->relkind == RELKIND_COMPOSITE_TYPE)
        ATTypedTableRecursion(wqueue, rel, cmd, lockmode, context);
}
 
/*
 * When the data type of a column is changed, a rewrite might not be required
 * if the new type is sufficiently identical to the old one, and the USING
 * clause isn't trying to insert some other value.  It's safe to skip the
 * rewrite in these cases:
 *
 * - the old type is binary coercible to the new type
 * - the new type is an unconstrained domain over the old type
 * - {NEW,OLD} or {OLD,NEW} is {timestamptz,timestamp} and the timezone is UTC
 *
 * In the case of a constrained domain, we could get by with scanning the
 * table and checking the constraint rather than actually rewriting it, but we
 * don't currently try to do that.
 */
static bool
ATColumnChangeRequiresRewrite(Node *expr, AttrNumber varattno)
{
    Assert(expr != NULL);
 
    for (;;)
    {
        /* only one varno, so no need to check that */
        if (IsA(expr, Var) && ((Var *) expr)->varattno == varattno)
            return false;
        else if (IsA(expr, RelabelType))
            expr = (Node *) ((RelabelType *) expr)->arg;
        else if (IsA(expr, CoerceToDomain))
        {
            CoerceToDomain *d = (CoerceToDomain *) expr;
 
            if (DomainHasConstraints(d->resulttype))
                return true;
            expr = (Node *) d->arg;
        }
        else if (IsA(expr, FuncExpr))
        {
            FuncExpr   *f = (FuncExpr *) expr;
 
            switch (f->funcid)
            {
                case F_TIMESTAMPTZ_TIMESTAMP:
                case F_TIMESTAMP_TIMESTAMPTZ:
                    if (TimestampTimestampTzRequiresRewrite())
                        return true;
                    else
                        expr = linitial(f->args);
                    break;
                default:
                    return true;
            }
        }
        else
            return true;
    }
}
 
/*
 * ALTER COLUMN .. SET DATA TYPE
 *
 * Return the address of the modified column.
 */
static ObjectAddress
ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
                      AlterTableCmd *cmd, LOCKMODE lockmode)
{
    char       *colName = cmd->name;
    ColumnDef  *def = (ColumnDef *) cmd->def;
    TypeName   *typeName = def->typeName;
    HeapTuple   heapTup;
    Form_pg_attribute attTup,
                attOldTup;
    AttrNumber  attnum;
    HeapTuple   typeTuple;
    Form_pg_type tform;
    Oid         targettype;
    int32       targettypmod;
    Oid         targetcollid;
    Node       *defaultexpr;
    Relation    attrelation;
    Relation    depRel;
    ScanKeyData key[3];
    SysScanDesc scan;
    HeapTuple   depTup;
    ObjectAddress address;
 
    /*
     * Clear all the missing values if we're rewriting the table, since this
     * renders them pointless.
     */
    if (tab->rewrite)
    {
        Relation    newrel;
 
        newrel = table_open(RelationGetRelid(rel), NoLock);
        RelationClearMissing(newrel);
        relation_close(newrel, NoLock);
        /* make sure we don't conflict with later attribute modifications */
        CommandCounterIncrement();
    }
 
    attrelation = table_open(AttributeRelationId, RowExclusiveLock);
 
    /* Look up the target column */
    heapTup = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(heapTup)) /* shouldn't happen */
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
    attTup = (Form_pg_attribute) GETSTRUCT(heapTup);
    attnum = attTup->attnum;
    attOldTup = TupleDescAttr(tab->oldDesc, attnum - 1);
 
    /* Check for multiple ALTER TYPE on same column --- can't cope */
    if (attTup->atttypid != attOldTup->atttypid ||
        attTup->atttypmod != attOldTup->atttypmod)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter type of column \"%s\" twice",
                        colName)));
 
    /* Look up the target type (should not fail, since prep found it) */
    typeTuple = typenameType(NULL, typeName, &targettypmod);
    tform = (Form_pg_type) GETSTRUCT(typeTuple);
    targettype = tform->oid;
    /* And the collation */
    targetcollid = GetColumnDefCollation(NULL, def, targettype);
 
    /*
     * If there is a default expression for the column, get it and ensure we
     * can coerce it to the new datatype.  (We must do this before changing
     * the column type, because build_column_default itself will try to
     * coerce, and will not issue the error message we want if it fails.)
     *
     * We remove any implicit coercion steps at the top level of the old
     * default expression; this has been agreed to satisfy the principle of
     * least surprise.  (The conversion to the new column type should act like
     * it started from what the user sees as the stored expression, and the
     * implicit coercions aren't going to be shown.)
     */
    if (attTup->atthasdef)
    {
        defaultexpr = build_column_default(rel, attnum);
        Assert(defaultexpr);
        defaultexpr = strip_implicit_coercions(defaultexpr);
        defaultexpr = coerce_to_target_type(NULL,   /* no UNKNOWN params */
                                            defaultexpr, exprType(defaultexpr),
                                            targettype, targettypmod,
                                            COERCION_ASSIGNMENT,
                                            COERCE_IMPLICIT_CAST,
                                            -1);
        if (defaultexpr == NULL)
        {
            if (attTup->attgenerated)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("generation expression for column \"%s\" cannot be cast automatically to type %s",
                                colName, format_type_be(targettype))));
            else
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("default for column \"%s\" cannot be cast automatically to type %s",
                                colName, format_type_be(targettype))));
        }
    }
    else
        defaultexpr = NULL;
 
    /*
     * Find everything that depends on the column (constraints, indexes, etc),
     * and record enough information to let us recreate the objects.
     *
     * The actual recreation does not happen here, but only after we have
     * performed all the individual ALTER TYPE operations.  We have to save
     * the info before executing ALTER TYPE, though, else the deparser will
     * get confused.
     */
    RememberAllDependentForRebuilding(tab, AT_AlterColumnType, rel, attnum, colName);
 
    /*
     * Now scan for dependencies of this column on other things.  The only
     * things we should find are the dependency on the column datatype and
     * possibly a collation dependency.  Those can be removed.
     */
    depRel = table_open(DependRelationId, RowExclusiveLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_depend_classid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationRelationId));
    ScanKeyInit(&key[1],
                Anum_pg_depend_objid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(rel)));
    ScanKeyInit(&key[2],
                Anum_pg_depend_objsubid,
                BTEqualStrategyNumber, F_INT4EQ,
                Int32GetDatum((int32) attnum));
 
    scan = systable_beginscan(depRel, DependDependerIndexId, true,
                              NULL, 3, key);
 
    while (HeapTupleIsValid(depTup = systable_getnext(scan)))
    {
        Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(depTup);
        ObjectAddress foundObject;
 
        foundObject.classId = foundDep->refclassid;
        foundObject.objectId = foundDep->refobjid;
        foundObject.objectSubId = foundDep->refobjsubid;
 
        if (foundDep->deptype != DEPENDENCY_NORMAL)
            elog(ERROR, "found unexpected dependency type '%c'",
                 foundDep->deptype);
        if (!(foundDep->refclassid == TypeRelationId &&
              foundDep->refobjid == attTup->atttypid) &&
            !(foundDep->refclassid == CollationRelationId &&
              foundDep->refobjid == attTup->attcollation))
            elog(ERROR, "found unexpected dependency for column: %s",
                 getObjectDescription(&foundObject, false));
 
        CatalogTupleDelete(depRel, &depTup->t_self);
    }
 
    systable_endscan(scan);
 
    table_close(depRel, RowExclusiveLock);
 
    /*
     * Here we go --- change the recorded column type and collation.  (Note
     * heapTup is a copy of the syscache entry, so okay to scribble on.) First
     * fix up the missing value if any.
     */
    if (attTup->atthasmissing)
    {
        Datum       missingval;
        bool        missingNull;
 
        /* if rewrite is true the missing value should already be cleared */
        Assert(tab->rewrite == 0);
 
        /* Get the missing value datum */
        missingval = heap_getattr(heapTup,
                                  Anum_pg_attribute_attmissingval,
                                  attrelation->rd_att,
                                  &missingNull);
 
        /* if it's a null array there is nothing to do */
 
        if (!missingNull)
        {
            /*
             * Get the datum out of the array and repack it in a new array
             * built with the new type data. We assume that since the table
             * doesn't need rewriting, the actual Datum doesn't need to be
             * changed, only the array metadata.
             */
 
            int         one = 1;
            bool        isNull;
            Datum       valuesAtt[Natts_pg_attribute] = {0};
            bool        nullsAtt[Natts_pg_attribute] = {0};
            bool        replacesAtt[Natts_pg_attribute] = {0};
            HeapTuple   newTup;
 
            missingval = array_get_element(missingval,
                                           1,
                                           &one,
                                           0,
                                           attTup->attlen,
                                           attTup->attbyval,
                                           attTup->attalign,
                                           &isNull);
            missingval = PointerGetDatum(construct_array(&missingval,
                                                         1,
                                                         targettype,
                                                         tform->typlen,
                                                         tform->typbyval,
                                                         tform->typalign));
 
            valuesAtt[Anum_pg_attribute_attmissingval - 1] = missingval;
            replacesAtt[Anum_pg_attribute_attmissingval - 1] = true;
            nullsAtt[Anum_pg_attribute_attmissingval - 1] = false;
 
            newTup = heap_modify_tuple(heapTup, RelationGetDescr(attrelation),
                                       valuesAtt, nullsAtt, replacesAtt);
            heap_freetuple(heapTup);
            heapTup = newTup;
            attTup = (Form_pg_attribute) GETSTRUCT(heapTup);
        }
    }
 
    attTup->atttypid = targettype;
    attTup->atttypmod = targettypmod;
    attTup->attcollation = targetcollid;
    if (list_length(typeName->arrayBounds) > PG_INT16_MAX)
        ereport(ERROR,
                errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                errmsg("too many array dimensions"));
    attTup->attndims = list_length(typeName->arrayBounds);
    attTup->attlen = tform->typlen;
    attTup->attbyval = tform->typbyval;
    attTup->attalign = tform->typalign;
    attTup->attstorage = tform->typstorage;
    attTup->attcompression = InvalidCompressionMethod;
 
    ReleaseSysCache(typeTuple);
 
    CatalogTupleUpdate(attrelation, &heapTup->t_self, heapTup);
 
    table_close(attrelation, RowExclusiveLock);
 
    /* Install dependencies on new datatype and collation */
    add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype);
    add_column_collation_dependency(RelationGetRelid(rel), attnum, targetcollid);
 
    /*
     * Drop any pg_statistic entry for the column, since it's now wrong type
     */
    RemoveStatistics(RelationGetRelid(rel), attnum);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), attnum);
 
    /*
     * Update the default, if present, by brute force --- remove and re-add
     * the default.  Probably unsafe to take shortcuts, since the new version
     * may well have additional dependencies.  (It's okay to do this now,
     * rather than after other ALTER TYPE commands, since the default won't
     * depend on other column types.)
     */
    if (defaultexpr)
    {
        /*
         * If it's a GENERATED default, drop its dependency records, in
         * particular its INTERNAL dependency on the column, which would
         * otherwise cause dependency.c to refuse to perform the deletion.
         */
        if (attTup->attgenerated)
        {
            Oid         attrdefoid = GetAttrDefaultOid(RelationGetRelid(rel), attnum);
 
            if (!OidIsValid(attrdefoid))
                elog(ERROR, "could not find attrdef tuple for relation %u attnum %d",
                     RelationGetRelid(rel), attnum);
            (void) deleteDependencyRecordsFor(AttrDefaultRelationId, attrdefoid, false);
        }
 
        /*
         * Make updates-so-far visible, particularly the new pg_attribute row
         * which will be updated again.
         */
        CommandCounterIncrement();
 
        /*
         * We use RESTRICT here for safety, but at present we do not expect
         * anything to depend on the default.
         */
        RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, true,
                          true);
 
        StoreAttrDefault(rel, attnum, defaultexpr, true, false);
    }
 
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
 
    /* Cleanup */
    heap_freetuple(heapTup);
 
    return address;
}
 
/*
 * Subroutine for ATExecAlterColumnType and ATExecSetExpression: Find everything
 * that depends on the column (constraints, indexes, etc), and record enough
 * information to let us recreate the objects.
 */
static void
RememberAllDependentForRebuilding(AlteredTableInfo *tab, AlterTableType subtype,
                                  Relation rel, AttrNumber attnum, const char *colName)
{
    Relation    depRel;
    ScanKeyData key[3];
    SysScanDesc scan;
    HeapTuple   depTup;
 
    Assert(subtype == AT_AlterColumnType || subtype == AT_SetExpression);
 
    depRel = table_open(DependRelationId, RowExclusiveLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_depend_refclassid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationRelationId));
    ScanKeyInit(&key[1],
                Anum_pg_depend_refobjid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(rel)));
    ScanKeyInit(&key[2],
                Anum_pg_depend_refobjsubid,
                BTEqualStrategyNumber, F_INT4EQ,
                Int32GetDatum((int32) attnum));
 
    scan = systable_beginscan(depRel, DependReferenceIndexId, true,
                              NULL, 3, key);
 
    while (HeapTupleIsValid(depTup = systable_getnext(scan)))
    {
        Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(depTup);
        ObjectAddress foundObject;
 
        foundObject.classId = foundDep->classid;
        foundObject.objectId = foundDep->objid;
        foundObject.objectSubId = foundDep->objsubid;
 
        switch (foundObject.classId)
        {
            case RelationRelationId:
                {
                    char        relKind = get_rel_relkind(foundObject.objectId);
 
                    if (relKind == RELKIND_INDEX ||
                        relKind == RELKIND_PARTITIONED_INDEX)
                    {
                        Assert(foundObject.objectSubId == 0);
                        RememberIndexForRebuilding(foundObject.objectId, tab);
                    }
                    else if (relKind == RELKIND_SEQUENCE)
                    {
                        /*
                         * This must be a SERIAL column's sequence.  We need
                         * not do anything to it.
                         */
                        Assert(foundObject.objectSubId == 0);
                    }
                    else
                    {
                        /* Not expecting any other direct dependencies... */
                        elog(ERROR, "unexpected object depending on column: %s",
                             getObjectDescription(&foundObject, false));
                    }
                    break;
                }
 
            case ConstraintRelationId:
                Assert(foundObject.objectSubId == 0);
                RememberConstraintForRebuilding(foundObject.objectId, tab);
                break;
 
            case ProcedureRelationId:
 
                /*
                 * A new-style SQL function can depend on a column, if that
                 * column is referenced in the parsed function body.  Ideally
                 * we'd automatically update the function by deparsing and
                 * reparsing it, but that's risky and might well fail anyhow.
                 * FIXME someday.
                 *
                 * This is only a problem for AT_AlterColumnType, not
                 * AT_SetExpression.
                 */
                if (subtype == AT_AlterColumnType)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot alter type of a column used by a function or procedure"),
                             errdetail("%s depends on column \"%s\"",
                                       getObjectDescription(&foundObject, false),
                                       colName)));
                break;
 
            case RewriteRelationId:
 
                /*
                 * View/rule bodies have pretty much the same issues as
                 * function bodies.  FIXME someday.
                 */
                if (subtype == AT_AlterColumnType)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot alter type of a column used by a view or rule"),
                             errdetail("%s depends on column \"%s\"",
                                       getObjectDescription(&foundObject, false),
                                       colName)));
                break;
 
            case TriggerRelationId:
 
                /*
                 * A trigger can depend on a column because the column is
                 * specified as an update target, or because the column is
                 * used in the trigger's WHEN condition.  The first case would
                 * not require any extra work, but the second case would
                 * require updating the WHEN expression, which has the same
                 * issues as above.  Since we can't easily tell which case
                 * applies, we punt for both.  FIXME someday.
                 */
                if (subtype == AT_AlterColumnType)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot alter type of a column used in a trigger definition"),
                             errdetail("%s depends on column \"%s\"",
                                       getObjectDescription(&foundObject, false),
                                       colName)));
                break;
 
            case PolicyRelationId:
 
                /*
                 * A policy can depend on a column because the column is
                 * specified in the policy's USING or WITH CHECK qual
                 * expressions.  It might be possible to rewrite and recheck
                 * the policy expression, but punt for now.  It's certainly
                 * easy enough to remove and recreate the policy; still, FIXME
                 * someday.
                 */
                if (subtype == AT_AlterColumnType)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot alter type of a column used in a policy definition"),
                             errdetail("%s depends on column \"%s\"",
                                       getObjectDescription(&foundObject, false),
                                       colName)));
                break;
 
            case AttrDefaultRelationId:
                {
                    ObjectAddress col = GetAttrDefaultColumnAddress(foundObject.objectId);
 
                    if (col.objectId == RelationGetRelid(rel) &&
                        col.objectSubId == attnum)
                    {
                        /*
                         * Ignore the column's own default expression.  The
                         * caller deals with it.
                         */
                    }
                    else
                    {
                        /*
                         * This must be a reference from the expression of a
                         * generated column elsewhere in the same table.
                         * Changing the type/generated expression of a column
                         * that is used by a generated column is not allowed
                         * by SQL standard, so just punt for now.  It might be
                         * doable with some thinking and effort.
                         */
                        if (subtype == AT_AlterColumnType)
                            ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("cannot alter type of a column used by a generated column"),
                                     errdetail("Column \"%s\" is used by generated column \"%s\".",
                                               colName,
                                               get_attname(col.objectId,
                                                           col.objectSubId,
                                                           false))));
                    }
                    break;
                }
 
            case StatisticExtRelationId:
 
                /*
                 * Give the extended-stats machinery a chance to fix anything
                 * that this column type change would break.
                 */
                RememberStatisticsForRebuilding(foundObject.objectId, tab);
                break;
 
            case PublicationRelRelationId:
 
                /*
                 * Column reference in a PUBLICATION ... FOR TABLE ... WHERE
                 * clause.  Same issues as above.  FIXME someday.
                 */
                if (subtype == AT_AlterColumnType)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot alter type of a column used by a publication WHERE clause"),
                             errdetail("%s depends on column \"%s\"",
                                       getObjectDescription(&foundObject, false),
                                       colName)));
                break;
 
            default:
 
                /*
                 * We don't expect any other sorts of objects to depend on a
                 * column.
                 */
                elog(ERROR, "unexpected object depending on column: %s",
                     getObjectDescription(&foundObject, false));
                break;
        }
    }
 
    systable_endscan(scan);
    table_close(depRel, NoLock);
}
 
/*
 * Subroutine for ATExecAlterColumnType: remember that a replica identity
 * needs to be reset.
 */
static void
RememberReplicaIdentityForRebuilding(Oid indoid, AlteredTableInfo *tab)
{
    if (!get_index_isreplident(indoid))
        return;
 
    if (tab->replicaIdentityIndex)
        elog(ERROR, "relation %u has multiple indexes marked as replica identity", tab->relid);
 
    tab->replicaIdentityIndex = get_rel_name(indoid);
}
 
/*
 * Subroutine for ATExecAlterColumnType: remember any clustered index.
 */
static void
RememberClusterOnForRebuilding(Oid indoid, AlteredTableInfo *tab)
{
    if (!get_index_isclustered(indoid))
        return;
 
    if (tab->clusterOnIndex)
        elog(ERROR, "relation %u has multiple clustered indexes", tab->relid);
 
    tab->clusterOnIndex = get_rel_name(indoid);
}
 
/*
 * Subroutine for ATExecAlterColumnType: remember that a constraint needs
 * to be rebuilt (which we might already know).
 */
static void
RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab)
{
    /*
     * This de-duplication check is critical for two independent reasons: we
     * mustn't try to recreate the same constraint twice, and if a constraint
     * depends on more than one column whose type is to be altered, we must
     * capture its definition string before applying any of the column type
     * changes.  ruleutils.c will get confused if we ask again later.
     */
    if (!list_member_oid(tab->changedConstraintOids, conoid))
    {
        /* OK, capture the constraint's existing definition string */
        char       *defstring = pg_get_constraintdef_command(conoid);
        Oid         indoid;
 
        tab->changedConstraintOids = lappend_oid(tab->changedConstraintOids,
                                                 conoid);
        tab->changedConstraintDefs = lappend(tab->changedConstraintDefs,
                                             defstring);
 
        /*
         * For the index of a constraint, if any, remember if it is used for
         * the table's replica identity or if it is a clustered index, so that
         * ATPostAlterTypeCleanup() can queue up commands necessary to restore
         * those properties.
         */
        indoid = get_constraint_index(conoid);
        if (OidIsValid(indoid))
        {
            RememberReplicaIdentityForRebuilding(indoid, tab);
            RememberClusterOnForRebuilding(indoid, tab);
        }
    }
}
 
/*
 * Subroutine for ATExecAlterColumnType: remember that an index needs
 * to be rebuilt (which we might already know).
 */
static void
RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab)
{
    /*
     * This de-duplication check is critical for two independent reasons: we
     * mustn't try to recreate the same index twice, and if an index depends
     * on more than one column whose type is to be altered, we must capture
     * its definition string before applying any of the column type changes.
     * ruleutils.c will get confused if we ask again later.
     */
    if (!list_member_oid(tab->changedIndexOids, indoid))
    {
        /*
         * Before adding it as an index-to-rebuild, we'd better see if it
         * belongs to a constraint, and if so rebuild the constraint instead.
         * Typically this check fails, because constraint indexes normally
         * have only dependencies on their constraint.  But it's possible for
         * such an index to also have direct dependencies on table columns,
         * for example with a partial exclusion constraint.
         */
        Oid         conoid = get_index_constraint(indoid);
 
        if (OidIsValid(conoid))
        {
            RememberConstraintForRebuilding(conoid, tab);
        }
        else
        {
            /* OK, capture the index's existing definition string */
            char       *defstring = pg_get_indexdef_string(indoid);
 
            tab->changedIndexOids = lappend_oid(tab->changedIndexOids,
                                                indoid);
            tab->changedIndexDefs = lappend(tab->changedIndexDefs,
                                            defstring);
 
            /*
             * Remember if this index is used for the table's replica identity
             * or if it is a clustered index, so that ATPostAlterTypeCleanup()
             * can queue up commands necessary to restore those properties.
             */
            RememberReplicaIdentityForRebuilding(indoid, tab);
            RememberClusterOnForRebuilding(indoid, tab);
        }
    }
}
 
/*
 * Subroutine for ATExecAlterColumnType: remember that a statistics object
 * needs to be rebuilt (which we might already know).
 */
static void
RememberStatisticsForRebuilding(Oid stxoid, AlteredTableInfo *tab)
{
    /*
     * This de-duplication check is critical for two independent reasons: we
     * mustn't try to recreate the same statistics object twice, and if the
     * statistics object depends on more than one column whose type is to be
     * altered, we must capture its definition string before applying any of
     * the type changes. ruleutils.c will get confused if we ask again later.
     */
    if (!list_member_oid(tab->changedStatisticsOids, stxoid))
    {
        /* OK, capture the statistics object's existing definition string */
        char       *defstring = pg_get_statisticsobjdef_string(stxoid);
 
        tab->changedStatisticsOids = lappend_oid(tab->changedStatisticsOids,
                                                 stxoid);
        tab->changedStatisticsDefs = lappend(tab->changedStatisticsDefs,
                                             defstring);
    }
}
 
/*
 * Cleanup after we've finished all the ALTER TYPE or SET EXPRESSION
 * operations for a particular relation.  We have to drop and recreate all the
 * indexes and constraints that depend on the altered columns.  We do the
 * actual dropping here, but re-creation is managed by adding work queue
 * entries to do those steps later.
 */
static void
ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode)
{
    ObjectAddress obj;
    ObjectAddresses *objects;
    ListCell   *def_item;
    ListCell   *oid_item;
 
    /*
     * Collect all the constraints and indexes to drop so we can process them
     * in a single call.  That way we don't have to worry about dependencies
     * among them.
     */
    objects = new_object_addresses();
 
    /*
     * Re-parse the index and constraint definitions, and attach them to the
     * appropriate work queue entries.  We do this before dropping because in
     * the case of a FOREIGN KEY constraint, we might not yet have exclusive
     * lock on the table the constraint is attached to, and we need to get
     * that before reparsing/dropping.
     *
     * We can't rely on the output of deparsing to tell us which relation to
     * operate on, because concurrent activity might have made the name
     * resolve differently.  Instead, we've got to use the OID of the
     * constraint or index we're processing to figure out which relation to
     * operate on.
     */
    forboth(oid_item, tab->changedConstraintOids,
            def_item, tab->changedConstraintDefs)
    {
        Oid         oldId = lfirst_oid(oid_item);
        HeapTuple   tup;
        Form_pg_constraint con;
        Oid         relid;
        Oid         confrelid;
        char        contype;
        bool        conislocal;
 
        tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(oldId));
        if (!HeapTupleIsValid(tup)) /* should not happen */
            elog(ERROR, "cache lookup failed for constraint %u", oldId);
        con = (Form_pg_constraint) GETSTRUCT(tup);
        if (OidIsValid(con->conrelid))
            relid = con->conrelid;
        else
        {
            /* must be a domain constraint */
            relid = get_typ_typrelid(getBaseType(con->contypid));
            if (!OidIsValid(relid))
                elog(ERROR, "could not identify relation associated with constraint %u", oldId);
        }
        confrelid = con->confrelid;
        contype = con->contype;
        conislocal = con->conislocal;
        ReleaseSysCache(tup);
 
        ObjectAddressSet(obj, ConstraintRelationId, oldId);
        add_exact_object_address(&obj, objects);
 
        /*
         * If the constraint is inherited (only), we don't want to inject a
         * new definition here; it'll get recreated when ATAddCheckConstraint
         * recurses from adding the parent table's constraint.  But we had to
         * carry the info this far so that we can drop the constraint below.
         */
        if (!conislocal)
            continue;
 
        /*
         * When rebuilding an FK constraint that references the table we're
         * modifying, we might not yet have any lock on the FK's table, so get
         * one now.  We'll need AccessExclusiveLock for the DROP CONSTRAINT
         * step, so there's no value in asking for anything weaker.
         */
        if (relid != tab->relid && contype == CONSTRAINT_FOREIGN)
            LockRelationOid(relid, AccessExclusiveLock);
 
        ATPostAlterTypeParse(oldId, relid, confrelid,
                             (char *) lfirst(def_item),
                             wqueue, lockmode, tab->rewrite);
    }
    forboth(oid_item, tab->changedIndexOids,
            def_item, tab->changedIndexDefs)
    {
        Oid         oldId = lfirst_oid(oid_item);
        Oid         relid;
 
        relid = IndexGetRelation(oldId, false);
        ATPostAlterTypeParse(oldId, relid, InvalidOid,
                             (char *) lfirst(def_item),
                             wqueue, lockmode, tab->rewrite);
 
        ObjectAddressSet(obj, RelationRelationId, oldId);
        add_exact_object_address(&obj, objects);
    }
 
    /* add dependencies for new statistics */
    forboth(oid_item, tab->changedStatisticsOids,
            def_item, tab->changedStatisticsDefs)
    {
        Oid         oldId = lfirst_oid(oid_item);
        Oid         relid;
 
        relid = StatisticsGetRelation(oldId, false);
        ATPostAlterTypeParse(oldId, relid, InvalidOid,
                             (char *) lfirst(def_item),
                             wqueue, lockmode, tab->rewrite);
 
        ObjectAddressSet(obj, StatisticExtRelationId, oldId);
        add_exact_object_address(&obj, objects);
    }
 
    /*
     * Queue up command to restore replica identity index marking
     */
    if (tab->replicaIdentityIndex)
    {
        AlterTableCmd *cmd = makeNode(AlterTableCmd);
        ReplicaIdentityStmt *subcmd = makeNode(ReplicaIdentityStmt);
 
        subcmd->identity_type = REPLICA_IDENTITY_INDEX;
        subcmd->name = tab->replicaIdentityIndex;
        cmd->subtype = AT_ReplicaIdentity;
        cmd->def = (Node *) subcmd;
 
        /* do it after indexes and constraints */
        tab->subcmds[AT_PASS_OLD_CONSTR] =
            lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
    }
 
    /*
     * Queue up command to restore marking of index used for cluster.
     */
    if (tab->clusterOnIndex)
    {
        AlterTableCmd *cmd = makeNode(AlterTableCmd);
 
        cmd->subtype = AT_ClusterOn;
        cmd->name = tab->clusterOnIndex;
 
        /* do it after indexes and constraints */
        tab->subcmds[AT_PASS_OLD_CONSTR] =
            lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
    }
 
    /*
     * It should be okay to use DROP_RESTRICT here, since nothing else should
     * be depending on these objects.
     */
    performMultipleDeletions(objects, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
 
    free_object_addresses(objects);
 
    /*
     * The objects will get recreated during subsequent passes over the work
     * queue.
     */
}
 
/*
 * Parse the previously-saved definition string for a constraint, index or
 * statistics object against the newly-established column data type(s), and
 * queue up the resulting command parsetrees for execution.
 *
 * This might fail if, for example, you have a WHERE clause that uses an
 * operator that's not available for the new column type.
 */
static void
ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId, char *cmd,
                     List **wqueue, LOCKMODE lockmode, bool rewrite)
{
    List       *raw_parsetree_list;
    List       *querytree_list;
    ListCell   *list_item;
    Relation    rel;
 
    /*
     * We expect that we will get only ALTER TABLE and CREATE INDEX
     * statements. Hence, there is no need to pass them through
     * parse_analyze_*() or the rewriter, but instead we need to pass them
     * through parse_utilcmd.c to make them ready for execution.
     */
    raw_parsetree_list = raw_parser(cmd, RAW_PARSE_DEFAULT);
    querytree_list = NIL;
    foreach(list_item, raw_parsetree_list)
    {
        RawStmt    *rs = lfirst_node(RawStmt, list_item);
        Node       *stmt = rs->stmt;
 
        if (IsA(stmt, IndexStmt))
            querytree_list = lappend(querytree_list,
                                     transformIndexStmt(oldRelId,
                                                        (IndexStmt *) stmt,
                                                        cmd));
        else if (IsA(stmt, AlterTableStmt))
        {
            List       *beforeStmts;
            List       *afterStmts;
 
            stmt = (Node *) transformAlterTableStmt(oldRelId,
                                                    (AlterTableStmt *) stmt,
                                                    cmd,
                                                    &beforeStmts,
                                                    &afterStmts);
            querytree_list = list_concat(querytree_list, beforeStmts);
            querytree_list = lappend(querytree_list, stmt);
            querytree_list = list_concat(querytree_list, afterStmts);
        }
        else if (IsA(stmt, CreateStatsStmt))
            querytree_list = lappend(querytree_list,
                                     transformStatsStmt(oldRelId,
                                                        (CreateStatsStmt *) stmt,
                                                        cmd));
        else
            querytree_list = lappend(querytree_list, stmt);
    }
 
    /* Caller should already have acquired whatever lock we need. */
    rel = relation_open(oldRelId, NoLock);
 
    /*
     * Attach each generated command to the proper place in the work queue.
     * Note this could result in creation of entirely new work-queue entries.
     *
     * Also note that we have to tweak the command subtypes, because it turns
     * out that re-creation of indexes and constraints has to act a bit
     * differently from initial creation.
     */
    foreach(list_item, querytree_list)
    {
        Node       *stm = (Node *) lfirst(list_item);
        AlteredTableInfo *tab;
 
        tab = ATGetQueueEntry(wqueue, rel);
 
        if (IsA(stm, IndexStmt))
        {
            IndexStmt  *stmt = (IndexStmt *) stm;
            AlterTableCmd *newcmd;
 
            if (!rewrite)
                TryReuseIndex(oldId, stmt);
            stmt->reset_default_tblspc = true;
            /* keep the index's comment */
            stmt->idxcomment = GetComment(oldId, RelationRelationId, 0);
 
            newcmd = makeNode(AlterTableCmd);
            newcmd->subtype = AT_ReAddIndex;
            newcmd->def = (Node *) stmt;
            tab->subcmds[AT_PASS_OLD_INDEX] =
                lappend(tab->subcmds[AT_PASS_OLD_INDEX], newcmd);
        }
        else if (IsA(stm, AlterTableStmt))
        {
            AlterTableStmt *stmt = (AlterTableStmt *) stm;
            ListCell   *lcmd;
 
            foreach(lcmd, stmt->cmds)
            {
                AlterTableCmd *cmd = lfirst_node(AlterTableCmd, lcmd);
 
                if (cmd->subtype == AT_AddIndex)
                {
                    IndexStmt  *indstmt;
                    Oid         indoid;
 
                    indstmt = castNode(IndexStmt, cmd->def);
                    indoid = get_constraint_index(oldId);
 
                    if (!rewrite)
                        TryReuseIndex(indoid, indstmt);
                    /* keep any comment on the index */
                    indstmt->idxcomment = GetComment(indoid,
                                                     RelationRelationId, 0);
                    indstmt->reset_default_tblspc = true;
 
                    cmd->subtype = AT_ReAddIndex;
                    tab->subcmds[AT_PASS_OLD_INDEX] =
                        lappend(tab->subcmds[AT_PASS_OLD_INDEX], cmd);
 
                    /* recreate any comment on the constraint */
                    RebuildConstraintComment(tab,
                                             AT_PASS_OLD_INDEX,
                                             oldId,
                                             rel,
                                             NIL,
                                             indstmt->idxname);
                }
                else if (cmd->subtype == AT_AddConstraint)
                {
                    Constraint *con = castNode(Constraint, cmd->def);
 
                    con->old_pktable_oid = refRelId;
                    /* rewriting neither side of a FK */
                    if (con->contype == CONSTR_FOREIGN &&
                        !rewrite && tab->rewrite == 0)
                        TryReuseForeignKey(oldId, con);
                    con->reset_default_tblspc = true;
                    cmd->subtype = AT_ReAddConstraint;
                    tab->subcmds[AT_PASS_OLD_CONSTR] =
                        lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
 
                    /* recreate any comment on the constraint */
                    RebuildConstraintComment(tab,
                                             AT_PASS_OLD_CONSTR,
                                             oldId,
                                             rel,
                                             NIL,
                                             con->conname);
                }
                else if (cmd->subtype == AT_SetNotNull)
                {
                    /*
                     * The parser will create AT_SetNotNull subcommands for
                     * columns of PRIMARY KEY indexes/constraints, but we need
                     * not do anything with them here, because the columns'
                     * NOT NULL marks will already have been propagated into
                     * the new table definition.
                     */
                }
                else
                    elog(ERROR, "unexpected statement subtype: %d",
                         (int) cmd->subtype);
            }
        }
        else if (IsA(stm, AlterDomainStmt))
        {
            AlterDomainStmt *stmt = (AlterDomainStmt *) stm;
 
            if (stmt->subtype == 'C')   /* ADD CONSTRAINT */
            {
                Constraint *con = castNode(Constraint, stmt->def);
                AlterTableCmd *cmd = makeNode(AlterTableCmd);
 
                cmd->subtype = AT_ReAddDomainConstraint;
                cmd->def = (Node *) stmt;
                tab->subcmds[AT_PASS_OLD_CONSTR] =
                    lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
 
                /* recreate any comment on the constraint */
                RebuildConstraintComment(tab,
                                         AT_PASS_OLD_CONSTR,
                                         oldId,
                                         NULL,
                                         stmt->typeName,
                                         con->conname);
            }
            else
                elog(ERROR, "unexpected statement subtype: %d",
                     (int) stmt->subtype);
        }
        else if (IsA(stm, CreateStatsStmt))
        {
            CreateStatsStmt *stmt = (CreateStatsStmt *) stm;
            AlterTableCmd *newcmd;
 
            /* keep the statistics object's comment */
            stmt->stxcomment = GetComment(oldId, StatisticExtRelationId, 0);
 
            newcmd = makeNode(AlterTableCmd);
            newcmd->subtype = AT_ReAddStatistics;
            newcmd->def = (Node *) stmt;
            tab->subcmds[AT_PASS_MISC] =
                lappend(tab->subcmds[AT_PASS_MISC], newcmd);
        }
        else
            elog(ERROR, "unexpected statement type: %d",
                 (int) nodeTag(stm));
    }
 
    relation_close(rel, NoLock);
}
 
/*
 * Subroutine for ATPostAlterTypeParse() to recreate any existing comment
 * for a table or domain constraint that is being rebuilt.
 *
 * objid is the OID of the constraint.
 * Pass "rel" for a table constraint, or "domname" (domain's qualified name
 * as a string list) for a domain constraint.
 * (We could dig that info, as well as the conname, out of the pg_constraint
 * entry; but callers already have them so might as well pass them.)
 */
static void
RebuildConstraintComment(AlteredTableInfo *tab, AlterTablePass pass, Oid objid,
                         Relation rel, List *domname,
                         const char *conname)
{
    CommentStmt *cmd;
    char       *comment_str;
    AlterTableCmd *newcmd;
 
    /* Look for comment for object wanted, and leave if none */
    comment_str = GetComment(objid, ConstraintRelationId, 0);
    if (comment_str == NULL)
        return;
 
    /* Build CommentStmt node, copying all input data for safety */
    cmd = makeNode(CommentStmt);
    if (rel)
    {
        cmd->objtype = OBJECT_TABCONSTRAINT;
        cmd->object = (Node *)
            list_make3(makeString(get_namespace_name(RelationGetNamespace(rel))),
                       makeString(pstrdup(RelationGetRelationName(rel))),
                       makeString(pstrdup(conname)));
    }
    else
    {
        cmd->objtype = OBJECT_DOMCONSTRAINT;
        cmd->object = (Node *)
            list_make2(makeTypeNameFromNameList(copyObject(domname)),
                       makeString(pstrdup(conname)));
    }
    cmd->comment = comment_str;
 
    /* Append it to list of commands */
    newcmd = makeNode(AlterTableCmd);
    newcmd->subtype = AT_ReAddComment;
    newcmd->def = (Node *) cmd;
    tab->subcmds[pass] = lappend(tab->subcmds[pass], newcmd);
}
 
/*
 * Subroutine for ATPostAlterTypeParse().  Calls out to CheckIndexCompatible()
 * for the real analysis, then mutates the IndexStmt based on that verdict.
 */
static void
TryReuseIndex(Oid oldId, IndexStmt *stmt)
{
    if (CheckIndexCompatible(oldId,
                             stmt->accessMethod,
                             stmt->indexParams,
                             stmt->excludeOpNames,
                             stmt->iswithoutoverlaps))
    {
        Relation    irel = index_open(oldId, NoLock);
 
        /* If it's a partitioned index, there is no storage to share. */
        if (irel->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
        {
            stmt->oldNumber = irel->rd_locator.relNumber;
            stmt->oldCreateSubid = irel->rd_createSubid;
            stmt->oldFirstRelfilelocatorSubid = irel->rd_firstRelfilelocatorSubid;
        }
        index_close(irel, NoLock);
    }
}
 
/*
 * Subroutine for ATPostAlterTypeParse().
 *
 * Stash the old P-F equality operator into the Constraint node, for possible
 * use by ATAddForeignKeyConstraint() in determining whether revalidation of
 * this constraint can be skipped.
 */
static void
TryReuseForeignKey(Oid oldId, Constraint *con)
{
    HeapTuple   tup;
    Datum       adatum;
    ArrayType  *arr;
    Oid        *rawarr;
    int         numkeys;
    int         i;
 
    Assert(con->contype == CONSTR_FOREIGN);
    Assert(con->old_conpfeqop == NIL);  /* already prepared this node */
 
    tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(oldId));
    if (!HeapTupleIsValid(tup)) /* should not happen */
        elog(ERROR, "cache lookup failed for constraint %u", oldId);
 
    adatum = SysCacheGetAttrNotNull(CONSTROID, tup,
                                    Anum_pg_constraint_conpfeqop);
    arr = DatumGetArrayTypeP(adatum);   /* ensure not toasted */
    numkeys = ARR_DIMS(arr)[0];
    /* test follows the one in ri_FetchConstraintInfo() */
    if (ARR_NDIM(arr) != 1 ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != OIDOID)
        elog(ERROR, "conpfeqop is not a 1-D Oid array");
    rawarr = (Oid *) ARR_DATA_PTR(arr);
 
    /* stash a List of the operator Oids in our Constraint node */
    for (i = 0; i < numkeys; i++)
        con->old_conpfeqop = lappend_oid(con->old_conpfeqop, rawarr[i]);
 
    ReleaseSysCache(tup);
}
 
/*
 * ALTER COLUMN .. OPTIONS ( ... )
 *
 * Returns the address of the modified column
 */
static ObjectAddress
ATExecAlterColumnGenericOptions(Relation rel,
                                const char *colName,
                                List *options,
                                LOCKMODE lockmode)
{
    Relation    ftrel;
    Relation    attrel;
    ForeignServer *server;
    ForeignDataWrapper *fdw;
    HeapTuple   tuple;
    HeapTuple   newtuple;
    bool        isnull;
    Datum       repl_val[Natts_pg_attribute];
    bool        repl_null[Natts_pg_attribute];
    bool        repl_repl[Natts_pg_attribute];
    Datum       datum;
    Form_pg_foreign_table fttableform;
    Form_pg_attribute atttableform;
    AttrNumber  attnum;
    ObjectAddress address;
 
    if (options == NIL)
        return InvalidObjectAddress;
 
    /* First, determine FDW validator associated to the foreign table. */
    ftrel = table_open(ForeignTableRelationId, AccessShareLock);
    tuple = SearchSysCache1(FOREIGNTABLEREL, ObjectIdGetDatum(rel->rd_id));
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("foreign table \"%s\" does not exist",
                        RelationGetRelationName(rel))));
    fttableform = (Form_pg_foreign_table) GETSTRUCT(tuple);
    server = GetForeignServer(fttableform->ftserver);
    fdw = GetForeignDataWrapper(server->fdwid);
 
    table_close(ftrel, AccessShareLock);
    ReleaseSysCache(tuple);
 
    attrel = table_open(AttributeRelationId, RowExclusiveLock);
    tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        colName, RelationGetRelationName(rel))));
 
    /* Prevent them from altering a system attribute */
    atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = atttableform->attnum;
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"", colName)));
 
 
    /* Initialize buffers for new tuple values */
    memset(repl_val, 0, sizeof(repl_val));
    memset(repl_null, false, sizeof(repl_null));
    memset(repl_repl, false, sizeof(repl_repl));
 
    /* Extract the current options */
    datum = SysCacheGetAttr(ATTNAME,
                            tuple,
                            Anum_pg_attribute_attfdwoptions,
                            &isnull);
    if (isnull)
        datum = PointerGetDatum(NULL);
 
    /* Transform the options */
    datum = transformGenericOptions(AttributeRelationId,
                                    datum,
                                    options,
                                    fdw->fdwvalidator);
 
    if (PointerIsValid(DatumGetPointer(datum)))
        repl_val[Anum_pg_attribute_attfdwoptions - 1] = datum;
    else
        repl_null[Anum_pg_attribute_attfdwoptions - 1] = true;
 
    repl_repl[Anum_pg_attribute_attfdwoptions - 1] = true;
 
    /* Everything looks good - update the tuple */
 
    newtuple = heap_modify_tuple(tuple, RelationGetDescr(attrel),
                                 repl_val, repl_null, repl_repl);
 
    CatalogTupleUpdate(attrel, &newtuple->t_self, newtuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              atttableform->attnum);
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
 
    ReleaseSysCache(tuple);
 
    table_close(attrel, RowExclusiveLock);
 
    heap_freetuple(newtuple);
 
    return address;
}
 
/*
 * ALTER TABLE OWNER
 *
 * recursing is true if we are recursing from a table to its indexes,
 * sequences, or toast table.  We don't allow the ownership of those things to
 * be changed separately from the parent table.  Also, we can skip permission
 * checks (this is necessary not just an optimization, else we'd fail to
 * handle toast tables properly).
 *
 * recursing is also true if ALTER TYPE OWNER is calling us to fix up a
 * free-standing composite type.
 */
void
ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lockmode)
{
    Relation    target_rel;
    Relation    class_rel;
    HeapTuple   tuple;
    Form_pg_class tuple_class;
 
    /*
     * Get exclusive lock till end of transaction on the target table. Use
     * relation_open so that we can work on indexes and sequences.
     */
    target_rel = relation_open(relationOid, lockmode);
 
    /* Get its pg_class tuple, too */
    class_rel = table_open(RelationRelationId, RowExclusiveLock);
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relationOid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", relationOid);
    tuple_class = (Form_pg_class) GETSTRUCT(tuple);
 
    /* Can we change the ownership of this tuple? */
    switch (tuple_class->relkind)
    {
        case RELKIND_RELATION:
        case RELKIND_VIEW:
        case RELKIND_MATVIEW:
        case RELKIND_FOREIGN_TABLE:
        case RELKIND_PARTITIONED_TABLE:
            /* ok to change owner */
            break;
        case RELKIND_INDEX:
            if (!recursing)
            {
                /*
                 * Because ALTER INDEX OWNER used to be allowed, and in fact
                 * is generated by old versions of pg_dump, we give a warning
                 * and do nothing rather than erroring out.  Also, to avoid
                 * unnecessary chatter while restoring those old dumps, say
                 * nothing at all if the command would be a no-op anyway.
                 */
                if (tuple_class->relowner != newOwnerId)
                    ereport(WARNING,
                            (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                             errmsg("cannot change owner of index \"%s\"",
                                    NameStr(tuple_class->relname)),
                             errhint("Change the ownership of the index's table instead.")));
                /* quick hack to exit via the no-op path */
                newOwnerId = tuple_class->relowner;
            }
            break;
        case RELKIND_PARTITIONED_INDEX:
            if (recursing)
                break;
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot change owner of index \"%s\"",
                            NameStr(tuple_class->relname)),
                     errhint("Change the ownership of the index's table instead.")));
            break;
        case RELKIND_SEQUENCE:
            if (!recursing &&
                tuple_class->relowner != newOwnerId)
            {
                /* if it's an owned sequence, disallow changing it by itself */
                Oid         tableId;
                int32       colId;
 
                if (sequenceIsOwned(relationOid, DEPENDENCY_AUTO, &tableId, &colId) ||
                    sequenceIsOwned(relationOid, DEPENDENCY_INTERNAL, &tableId, &colId))
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot change owner of sequence \"%s\"",
                                    NameStr(tuple_class->relname)),
                             errdetail("Sequence \"%s\" is linked to table \"%s\".",
                                       NameStr(tuple_class->relname),
                                       get_rel_name(tableId))));
            }
            break;
        case RELKIND_COMPOSITE_TYPE:
            if (recursing)
                break;
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("\"%s\" is a composite type",
                            NameStr(tuple_class->relname)),
            /* translator: %s is an SQL ALTER command */
                     errhint("Use %s instead.",
                             "ALTER TYPE")));
            break;
        case RELKIND_TOASTVALUE:
            if (recursing)
                break;
            /* FALL THRU */
        default:
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot change owner of relation \"%s\"",
                            NameStr(tuple_class->relname)),
                     errdetail_relkind_not_supported(tuple_class->relkind)));
    }
 
    /*
     * If the new owner is the same as the existing owner, consider the
     * command to have succeeded.  This is for dump restoration purposes.
     */
    if (tuple_class->relowner != newOwnerId)
    {
        Datum       repl_val[Natts_pg_class];
        bool        repl_null[Natts_pg_class];
        bool        repl_repl[Natts_pg_class];
        Acl        *newAcl;
        Datum       aclDatum;
        bool        isNull;
        HeapTuple   newtuple;
 
        /* skip permission checks when recursing to index or toast table */
        if (!recursing)
        {
            /* Superusers can always do it */
            if (!superuser())
            {
                Oid         namespaceOid = tuple_class->relnamespace;
                AclResult   aclresult;
 
                /* Otherwise, must be owner of the existing object */
                if (!object_ownercheck(RelationRelationId, relationOid, GetUserId()))
                    aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relationOid)),
                                   RelationGetRelationName(target_rel));
 
                /* Must be able to become new owner */
                check_can_set_role(GetUserId(), newOwnerId);
 
                /* New owner must have CREATE privilege on namespace */
                aclresult = object_aclcheck(NamespaceRelationId, namespaceOid, newOwnerId,
                                            ACL_CREATE);
                if (aclresult != ACLCHECK_OK)
                    aclcheck_error(aclresult, OBJECT_SCHEMA,
                                   get_namespace_name(namespaceOid));
            }
        }
 
        memset(repl_null, false, sizeof(repl_null));
        memset(repl_repl, false, sizeof(repl_repl));
 
        repl_repl[Anum_pg_class_relowner - 1] = true;
        repl_val[Anum_pg_class_relowner - 1] = ObjectIdGetDatum(newOwnerId);
 
        /*
         * Determine the modified ACL for the new owner.  This is only
         * necessary when the ACL is non-null.
         */
        aclDatum = SysCacheGetAttr(RELOID, tuple,
                                   Anum_pg_class_relacl,
                                   &isNull);
        if (!isNull)
        {
            newAcl = aclnewowner(DatumGetAclP(aclDatum),
                                 tuple_class->relowner, newOwnerId);
            repl_repl[Anum_pg_class_relacl - 1] = true;
            repl_val[Anum_pg_class_relacl - 1] = PointerGetDatum(newAcl);
        }
 
        newtuple = heap_modify_tuple(tuple, RelationGetDescr(class_rel), repl_val, repl_null, repl_repl);
 
        CatalogTupleUpdate(class_rel, &newtuple->t_self, newtuple);
 
        heap_freetuple(newtuple);
 
        /*
         * We must similarly update any per-column ACLs to reflect the new
         * owner; for neatness reasons that's split out as a subroutine.
         */
        change_owner_fix_column_acls(relationOid,
                                     tuple_class->relowner,
                                     newOwnerId);
 
        /*
         * Update owner dependency reference, if any.  A composite type has
         * none, because it's tracked for the pg_type entry instead of here;
         * indexes and TOAST tables don't have their own entries either.
         */
        if (tuple_class->relkind != RELKIND_COMPOSITE_TYPE &&
            tuple_class->relkind != RELKIND_INDEX &&
            tuple_class->relkind != RELKIND_PARTITIONED_INDEX &&
            tuple_class->relkind != RELKIND_TOASTVALUE)
            changeDependencyOnOwner(RelationRelationId, relationOid,
                                    newOwnerId);
 
        /*
         * Also change the ownership of the table's row type, if it has one
         */
        if (OidIsValid(tuple_class->reltype))
            AlterTypeOwnerInternal(tuple_class->reltype, newOwnerId);
 
        /*
         * If we are operating on a table or materialized view, also change
         * the ownership of any indexes and sequences that belong to the
         * relation, as well as its toast table (if it has one).
         */
        if (tuple_class->relkind == RELKIND_RELATION ||
            tuple_class->relkind == RELKIND_PARTITIONED_TABLE ||
            tuple_class->relkind == RELKIND_MATVIEW ||
            tuple_class->relkind == RELKIND_TOASTVALUE)
        {
            List       *index_oid_list;
            ListCell   *i;
 
            /* Find all the indexes belonging to this relation */
            index_oid_list = RelationGetIndexList(target_rel);
 
            /* For each index, recursively change its ownership */
            foreach(i, index_oid_list)
                ATExecChangeOwner(lfirst_oid(i), newOwnerId, true, lockmode);
 
            list_free(index_oid_list);
        }
 
        /* If it has a toast table, recurse to change its ownership */
        if (tuple_class->reltoastrelid != InvalidOid)
            ATExecChangeOwner(tuple_class->reltoastrelid, newOwnerId,
                              true, lockmode);
 
        /* If it has dependent sequences, recurse to change them too */
        change_owner_recurse_to_sequences(relationOid, newOwnerId, lockmode);
    }
 
    InvokeObjectPostAlterHook(RelationRelationId, relationOid, 0);
 
    ReleaseSysCache(tuple);
    table_close(class_rel, RowExclusiveLock);
    relation_close(target_rel, NoLock);
}
 
/*
 * change_owner_fix_column_acls
 *
 * Helper function for ATExecChangeOwner.  Scan the columns of the table
 * and fix any non-null column ACLs to reflect the new owner.
 */
static void
change_owner_fix_column_acls(Oid relationOid, Oid oldOwnerId, Oid newOwnerId)
{
    Relation    attRelation;
    SysScanDesc scan;
    ScanKeyData key[1];
    HeapTuple   attributeTuple;
 
    attRelation = table_open(AttributeRelationId, RowExclusiveLock);
    ScanKeyInit(&key[0],
                Anum_pg_attribute_attrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relationOid));
    scan = systable_beginscan(attRelation, AttributeRelidNumIndexId,
                              true, NULL, 1, key);
    while (HeapTupleIsValid(attributeTuple = systable_getnext(scan)))
    {
        Form_pg_attribute att = (Form_pg_attribute) GETSTRUCT(attributeTuple);
        Datum       repl_val[Natts_pg_attribute];
        bool        repl_null[Natts_pg_attribute];
        bool        repl_repl[Natts_pg_attribute];
        Acl        *newAcl;
        Datum       aclDatum;
        bool        isNull;
        HeapTuple   newtuple;
 
        /* Ignore dropped columns */
        if (att->attisdropped)
            continue;
 
        aclDatum = heap_getattr(attributeTuple,
                                Anum_pg_attribute_attacl,
                                RelationGetDescr(attRelation),
                                &isNull);
        /* Null ACLs do not require changes */
        if (isNull)
            continue;
 
        memset(repl_null, false, sizeof(repl_null));
        memset(repl_repl, false, sizeof(repl_repl));
 
        newAcl = aclnewowner(DatumGetAclP(aclDatum),
                             oldOwnerId, newOwnerId);
        repl_repl[Anum_pg_attribute_attacl - 1] = true;
        repl_val[Anum_pg_attribute_attacl - 1] = PointerGetDatum(newAcl);
 
        newtuple = heap_modify_tuple(attributeTuple,
                                     RelationGetDescr(attRelation),
                                     repl_val, repl_null, repl_repl);
 
        CatalogTupleUpdate(attRelation, &newtuple->t_self, newtuple);
 
        heap_freetuple(newtuple);
    }
    systable_endscan(scan);
    table_close(attRelation, RowExclusiveLock);
}
 
/*
 * change_owner_recurse_to_sequences
 *
 * Helper function for ATExecChangeOwner.  Examines pg_depend searching
 * for sequences that are dependent on serial columns, and changes their
 * ownership.
 */
static void
change_owner_recurse_to_sequences(Oid relationOid, Oid newOwnerId, LOCKMODE lockmode)
{
    Relation    depRel;
    SysScanDesc scan;
    ScanKeyData key[2];
    HeapTuple   tup;
 
    /*
     * SERIAL sequences are those having an auto dependency on one of the
     * table's columns (we don't care *which* column, exactly).
     */
    depRel = table_open(DependRelationId, AccessShareLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_depend_refclassid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationRelationId));
    ScanKeyInit(&key[1],
                Anum_pg_depend_refobjid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relationOid));
    /* we leave refobjsubid unspecified */
 
    scan = systable_beginscan(depRel, DependReferenceIndexId, true,
                              NULL, 2, key);
 
    while (HeapTupleIsValid(tup = systable_getnext(scan)))
    {
        Form_pg_depend depForm = (Form_pg_depend) GETSTRUCT(tup);
        Relation    seqRel;
 
        /* skip dependencies other than auto dependencies on columns */
        if (depForm->refobjsubid == 0 ||
            depForm->classid != RelationRelationId ||
            depForm->objsubid != 0 ||
            !(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
            continue;
 
        /* Use relation_open just in case it's an index */
        seqRel = relation_open(depForm->objid, lockmode);
 
        /* skip non-sequence relations */
        if (RelationGetForm(seqRel)->relkind != RELKIND_SEQUENCE)
        {
            /* No need to keep the lock */
            relation_close(seqRel, lockmode);
            continue;
        }
 
        /* We don't need to close the sequence while we alter it. */
        ATExecChangeOwner(depForm->objid, newOwnerId, true, lockmode);
 
        /* Now we can close it.  Keep the lock till end of transaction. */
        relation_close(seqRel, NoLock);
    }
 
    systable_endscan(scan);
 
    relation_close(depRel, AccessShareLock);
}
 
/*
 * ALTER TABLE CLUSTER ON
 *
 * The only thing we have to do is to change the indisclustered bits.
 *
 * Return the address of the new clustering index.
 */
static ObjectAddress
ATExecClusterOn(Relation rel, const char *indexName, LOCKMODE lockmode)
{
    Oid         indexOid;
    ObjectAddress address;
 
    indexOid = get_relname_relid(indexName, rel->rd_rel->relnamespace);
 
    if (!OidIsValid(indexOid))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("index \"%s\" for table \"%s\" does not exist",
                        indexName, RelationGetRelationName(rel))));
 
    /* Check index is valid to cluster on */
    check_index_is_clusterable(rel, indexOid, lockmode);
 
    /* And do the work */
    mark_index_clustered(rel, indexOid, false);
 
    ObjectAddressSet(address,
                     RelationRelationId, indexOid);
 
    return address;
}
 
/*
 * ALTER TABLE SET WITHOUT CLUSTER
 *
 * We have to find any indexes on the table that have indisclustered bit
 * set and turn it off.
 */
static void
ATExecDropCluster(Relation rel, LOCKMODE lockmode)
{
    mark_index_clustered(rel, InvalidOid, false);
}
 
/*
 * Preparation phase for SET ACCESS METHOD
 *
 * Check that the access method exists and determine whether a change is
 * actually needed.
 */
static void
ATPrepSetAccessMethod(AlteredTableInfo *tab, Relation rel, const char *amname)
{
    Oid         amoid;
 
    /*
     * Look up the access method name and check that it differs from the
     * table's current AM.  If DEFAULT was specified for a partitioned table
     * (amname is NULL), set it to InvalidOid to reset the catalogued AM.
     */
    if (amname != NULL)
        amoid = get_table_am_oid(amname, false);
    else if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
        amoid = InvalidOid;
    else
        amoid = get_table_am_oid(default_table_access_method, false);
 
    /* if it's a match, phase 3 doesn't need to do anything */
    if (rel->rd_rel->relam == amoid)
        return;
 
    /* Save info for Phase 3 to do the real work */
    tab->rewrite |= AT_REWRITE_ACCESS_METHOD;
    tab->newAccessMethod = amoid;
    tab->chgAccessMethod = true;
}
 
/*
 * Special handling of ALTER TABLE SET ACCESS METHOD for relations with no
 * storage that have an interest in preserving AM.
 *
 * Since these have no storage, setting the access method is a catalog only
 * operation.
 */
static void
ATExecSetAccessMethodNoStorage(Relation rel, Oid newAccessMethodId)
{
    Relation    pg_class;
    Oid         oldAccessMethodId;
    HeapTuple   tuple;
    Form_pg_class rd_rel;
    Oid         reloid = RelationGetRelid(rel);
 
    /*
     * Shouldn't be called on relations having storage; these are processed in
     * phase 3.
     */
    Assert(!RELKIND_HAS_STORAGE(rel->rd_rel->relkind));
 
    /* Get a modifiable copy of the relation's pg_class row. */
    pg_class = table_open(RelationRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(reloid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", reloid);
    rd_rel = (Form_pg_class) GETSTRUCT(tuple);
 
    /* Update the pg_class row. */
    oldAccessMethodId = rd_rel->relam;
    rd_rel->relam = newAccessMethodId;
 
    /* Leave if no update required */
    if (rd_rel->relam == oldAccessMethodId)
    {
        heap_freetuple(tuple);
        table_close(pg_class, RowExclusiveLock);
        return;
    }
 
    CatalogTupleUpdate(pg_class, &tuple->t_self, tuple);
 
    /*
     * Update the dependency on the new access method.  No dependency is added
     * if the new access method is InvalidOid (default case).  Be very careful
     * that this has to compare the previous value stored in pg_class with the
     * new one.
     */
    if (!OidIsValid(oldAccessMethodId) && OidIsValid(rd_rel->relam))
    {
        ObjectAddress relobj,
                    referenced;
 
        /*
         * New access method is defined and there was no dependency
         * previously, so record a new one.
         */
        ObjectAddressSet(relobj, RelationRelationId, reloid);
        ObjectAddressSet(referenced, AccessMethodRelationId, rd_rel->relam);
        recordDependencyOn(&relobj, &referenced, DEPENDENCY_NORMAL);
    }
    else if (OidIsValid(oldAccessMethodId) &&
             !OidIsValid(rd_rel->relam))
    {
        /*
         * There was an access method defined, and no new one, so just remove
         * the existing dependency.
         */
        deleteDependencyRecordsForClass(RelationRelationId, reloid,
                                        AccessMethodRelationId,
                                        DEPENDENCY_NORMAL);
    }
    else
    {
        Assert(OidIsValid(oldAccessMethodId) &&
               OidIsValid(rd_rel->relam));
 
        /* Both are valid, so update the dependency */
        changeDependencyFor(RelationRelationId, reloid,
                            AccessMethodRelationId,
                            oldAccessMethodId, rd_rel->relam);
    }
 
    /* make the relam and dependency changes visible */
    CommandCounterIncrement();
 
    InvokeObjectPostAlterHook(RelationRelationId, RelationGetRelid(rel), 0);
 
    heap_freetuple(tuple);
    table_close(pg_class, RowExclusiveLock);
}
 
/*
 * ALTER TABLE SET TABLESPACE
 */
static void
ATPrepSetTableSpace(AlteredTableInfo *tab, Relation rel, const char *tablespacename, LOCKMODE lockmode)
{
    Oid         tablespaceId;
 
    /* Check that the tablespace exists */
    tablespaceId = get_tablespace_oid(tablespacename, false);
 
    /* Check permissions except when moving to database's default */
    if (OidIsValid(tablespaceId) && tablespaceId != MyDatabaseTableSpace)
    {
        AclResult   aclresult;
 
        aclresult = object_aclcheck(TableSpaceRelationId, tablespaceId, GetUserId(), ACL_CREATE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, OBJECT_TABLESPACE, tablespacename);
    }
 
    /* Save info for Phase 3 to do the real work */
    if (OidIsValid(tab->newTableSpace))
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("cannot have multiple SET TABLESPACE subcommands")));
 
    tab->newTableSpace = tablespaceId;
}
 
/*
 * Set, reset, or replace reloptions.
 */
static void
ATExecSetRelOptions(Relation rel, List *defList, AlterTableType operation,
                    LOCKMODE lockmode)
{
    Oid         relid;
    Relation    pgclass;
    HeapTuple   tuple;
    HeapTuple   newtuple;
    Datum       datum;
    bool        isnull;
    Datum       newOptions;
    Datum       repl_val[Natts_pg_class];
    bool        repl_null[Natts_pg_class];
    bool        repl_repl[Natts_pg_class];
    const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
 
    if (defList == NIL && operation != AT_ReplaceRelOptions)
        return;                 /* nothing to do */
 
    pgclass = table_open(RelationRelationId, RowExclusiveLock);
 
    /* Fetch heap tuple */
    relid = RelationGetRelid(rel);
    tuple = SearchSysCacheLocked1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", relid);
 
    if (operation == AT_ReplaceRelOptions)
    {
        /*
         * If we're supposed to replace the reloptions list, we just pretend
         * there were none before.
         */
        datum = (Datum) 0;
        isnull = true;
    }
    else
    {
        /* Get the old reloptions */
        datum = SysCacheGetAttr(RELOID, tuple, Anum_pg_class_reloptions,
                                &isnull);
    }
 
    /* Generate new proposed reloptions (text array) */
    newOptions = transformRelOptions(isnull ? (Datum) 0 : datum,
                                     defList, NULL, validnsps, false,
                                     operation == AT_ResetRelOptions);
 
    /* Validate */
    switch (rel->rd_rel->relkind)
    {
        case RELKIND_RELATION:
        case RELKIND_TOASTVALUE:
        case RELKIND_MATVIEW:
            (void) heap_reloptions(rel->rd_rel->relkind, newOptions, true);
            break;
        case RELKIND_PARTITIONED_TABLE:
            (void) partitioned_table_reloptions(newOptions, true);
            break;
        case RELKIND_VIEW:
            (void) view_reloptions(newOptions, true);
            break;
        case RELKIND_INDEX:
        case RELKIND_PARTITIONED_INDEX:
            (void) index_reloptions(rel->rd_indam->amoptions, newOptions, true);
            break;
        default:
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot set options for relation \"%s\"",
                            RelationGetRelationName(rel)),
                     errdetail_relkind_not_supported(rel->rd_rel->relkind)));
            break;
    }
 
    /* Special-case validation of view options */
    if (rel->rd_rel->relkind == RELKIND_VIEW)
    {
        Query      *view_query = get_view_query(rel);
        List       *view_options = untransformRelOptions(newOptions);
        ListCell   *cell;
        bool        check_option = false;
 
        foreach(cell, view_options)
        {
            DefElem    *defel = (DefElem *) lfirst(cell);
 
            if (strcmp(defel->defname, "check_option") == 0)
                check_option = true;
        }
 
        /*
         * If the check option is specified, look to see if the view is
         * actually auto-updatable or not.
         */
        if (check_option)
        {
            const char *view_updatable_error =
                view_query_is_auto_updatable(view_query, true);
 
            if (view_updatable_error)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),
                         errhint("%s", _(view_updatable_error))));
        }
    }
 
    /*
     * All we need do here is update the pg_class row; the new options will be
     * propagated into relcaches during post-commit cache inval.
     */
    memset(repl_val, 0, sizeof(repl_val));
    memset(repl_null, false, sizeof(repl_null));
    memset(repl_repl, false, sizeof(repl_repl));
 
    if (newOptions != (Datum) 0)
        repl_val[Anum_pg_class_reloptions - 1] = newOptions;
    else
        repl_null[Anum_pg_class_reloptions - 1] = true;
 
    repl_repl[Anum_pg_class_reloptions - 1] = true;
 
    newtuple = heap_modify_tuple(tuple, RelationGetDescr(pgclass),
                                 repl_val, repl_null, repl_repl);
 
    CatalogTupleUpdate(pgclass, &newtuple->t_self, newtuple);
    UnlockTuple(pgclass, &tuple->t_self, InplaceUpdateTupleLock);
 
    InvokeObjectPostAlterHook(RelationRelationId, RelationGetRelid(rel), 0);
 
    heap_freetuple(newtuple);
 
    ReleaseSysCache(tuple);
 
    /* repeat the whole exercise for the toast table, if there's one */
    if (OidIsValid(rel->rd_rel->reltoastrelid))
    {
        Relation    toastrel;
        Oid         toastid = rel->rd_rel->reltoastrelid;
 
        toastrel = table_open(toastid, lockmode);
 
        /* Fetch heap tuple */
        tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(toastid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for relation %u", toastid);
 
        if (operation == AT_ReplaceRelOptions)
        {
            /*
             * If we're supposed to replace the reloptions list, we just
             * pretend there were none before.
             */
            datum = (Datum) 0;
            isnull = true;
        }
        else
        {
            /* Get the old reloptions */
            datum = SysCacheGetAttr(RELOID, tuple, Anum_pg_class_reloptions,
                                    &isnull);
        }
 
        newOptions = transformRelOptions(isnull ? (Datum) 0 : datum,
                                         defList, "toast", validnsps, false,
                                         operation == AT_ResetRelOptions);
 
        (void) heap_reloptions(RELKIND_TOASTVALUE, newOptions, true);
 
        memset(repl_val, 0, sizeof(repl_val));
        memset(repl_null, false, sizeof(repl_null));
        memset(repl_repl, false, sizeof(repl_repl));
 
        if (newOptions != (Datum) 0)
            repl_val[Anum_pg_class_reloptions - 1] = newOptions;
        else
            repl_null[Anum_pg_class_reloptions - 1] = true;
 
        repl_repl[Anum_pg_class_reloptions - 1] = true;
 
        newtuple = heap_modify_tuple(tuple, RelationGetDescr(pgclass),
                                     repl_val, repl_null, repl_repl);
 
        CatalogTupleUpdate(pgclass, &newtuple->t_self, newtuple);
 
        InvokeObjectPostAlterHookArg(RelationRelationId,
                                     RelationGetRelid(toastrel), 0,
                                     InvalidOid, true);
 
        heap_freetuple(newtuple);
 
        ReleaseSysCache(tuple);
 
        table_close(toastrel, NoLock);
    }
 
    table_close(pgclass, RowExclusiveLock);
}
 
/*
 * Execute ALTER TABLE SET TABLESPACE for cases where there is no tuple
 * rewriting to be done, so we just want to copy the data as fast as possible.
 */
static void
ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode)
{
    Relation    rel;
    Oid         reltoastrelid;
    RelFileNumber newrelfilenumber;
    RelFileLocator newrlocator;
    List       *reltoastidxids = NIL;
    ListCell   *lc;
 
    /*
     * Need lock here in case we are recursing to toast table or index
     */
    rel = relation_open(tableOid, lockmode);
 
    /* Check first if relation can be moved to new tablespace */
    if (!CheckRelationTableSpaceMove(rel, newTableSpace))
    {
        InvokeObjectPostAlterHook(RelationRelationId,
                                  RelationGetRelid(rel), 0);
        relation_close(rel, NoLock);
        return;
    }
 
    reltoastrelid = rel->rd_rel->reltoastrelid;
    /* Fetch the list of indexes on toast relation if necessary */
    if (OidIsValid(reltoastrelid))
    {
        Relation    toastRel = relation_open(reltoastrelid, lockmode);
 
        reltoastidxids = RelationGetIndexList(toastRel);
        relation_close(toastRel, lockmode);
    }
 
    /*
     * Relfilenumbers are not unique in databases across tablespaces, so we
     * need to allocate a new one in the new tablespace.
     */
    newrelfilenumber = GetNewRelFileNumber(newTableSpace, NULL,
                                           rel->rd_rel->relpersistence);
 
    /* Open old and new relation */
    newrlocator = rel->rd_locator;
    newrlocator.relNumber = newrelfilenumber;
    newrlocator.spcOid = newTableSpace;
 
    /* hand off to AM to actually create new rel storage and copy the data */
    if (rel->rd_rel->relkind == RELKIND_INDEX)
    {
        index_copy_data(rel, newrlocator);
    }
    else
    {
        Assert(RELKIND_HAS_TABLE_AM(rel->rd_rel->relkind));
        table_relation_copy_data(rel, &newrlocator);
    }
 
    /*
     * Update the pg_class row.
     *
     * NB: This wouldn't work if ATExecSetTableSpace() were allowed to be
     * executed on pg_class or its indexes (the above copy wouldn't contain
     * the updated pg_class entry), but that's forbidden with
     * CheckRelationTableSpaceMove().
     */
    SetRelationTableSpace(rel, newTableSpace, newrelfilenumber);
 
    InvokeObjectPostAlterHook(RelationRelationId, RelationGetRelid(rel), 0);
 
    RelationAssumeNewRelfilelocator(rel);
 
    relation_close(rel, NoLock);
 
    /* Make sure the reltablespace change is visible */
    CommandCounterIncrement();
 
    /* Move associated toast relation and/or indexes, too */
    if (OidIsValid(reltoastrelid))
        ATExecSetTableSpace(reltoastrelid, newTableSpace, lockmode);
    foreach(lc, reltoastidxids)
        ATExecSetTableSpace(lfirst_oid(lc), newTableSpace, lockmode);
 
    /* Clean up */
    list_free(reltoastidxids);
}
 
/*
 * Special handling of ALTER TABLE SET TABLESPACE for relations with no
 * storage that have an interest in preserving tablespace.
 *
 * Since these have no storage the tablespace can be updated with a simple
 * metadata only operation to update the tablespace.
 */
static void
ATExecSetTableSpaceNoStorage(Relation rel, Oid newTableSpace)
{
    /*
     * Shouldn't be called on relations having storage; these are processed in
     * phase 3.
     */
    Assert(!RELKIND_HAS_STORAGE(rel->rd_rel->relkind));
 
    /* check if relation can be moved to its new tablespace */
    if (!CheckRelationTableSpaceMove(rel, newTableSpace))
    {
        InvokeObjectPostAlterHook(RelationRelationId,
                                  RelationGetRelid(rel),
                                  0);
        return;
    }
 
    /* Update can be done, so change reltablespace */
    SetRelationTableSpace(rel, newTableSpace, InvalidOid);
 
    InvokeObjectPostAlterHook(RelationRelationId, RelationGetRelid(rel), 0);
 
    /* Make sure the reltablespace change is visible */
    CommandCounterIncrement();
}
 
/*
 * Alter Table ALL ... SET TABLESPACE
 *
 * Allows a user to move all objects of some type in a given tablespace in the
 * current database to another tablespace.  Objects can be chosen based on the
 * owner of the object also, to allow users to move only their objects.
 * The user must have CREATE rights on the new tablespace, as usual.   The main
 * permissions handling is done by the lower-level table move function.
 *
 * All to-be-moved objects are locked first. If NOWAIT is specified and the
 * lock can't be acquired then we ereport(ERROR).
 */
Oid
AlterTableMoveAll(AlterTableMoveAllStmt *stmt)
{
    List       *relations = NIL;
    ListCell   *l;
    ScanKeyData key[1];
    Relation    rel;
    TableScanDesc scan;
    HeapTuple   tuple;
    Oid         orig_tablespaceoid;
    Oid         new_tablespaceoid;
    List       *role_oids = roleSpecsToIds(stmt->roles);
 
    /* Ensure we were not asked to move something we can't */
    if (stmt->objtype != OBJECT_TABLE && stmt->objtype != OBJECT_INDEX &&
        stmt->objtype != OBJECT_MATVIEW)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("only tables, indexes, and materialized views exist in tablespaces")));
 
    /* Get the orig and new tablespace OIDs */
    orig_tablespaceoid = get_tablespace_oid(stmt->orig_tablespacename, false);
    new_tablespaceoid = get_tablespace_oid(stmt->new_tablespacename, false);
 
    /* Can't move shared relations in to or out of pg_global */
    /* This is also checked by ATExecSetTableSpace, but nice to stop earlier */
    if (orig_tablespaceoid == GLOBALTABLESPACE_OID ||
        new_tablespaceoid == GLOBALTABLESPACE_OID)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("cannot move relations in to or out of pg_global tablespace")));
 
    /*
     * Must have CREATE rights on the new tablespace, unless it is the
     * database default tablespace (which all users implicitly have CREATE
     * rights on).
     */
    if (OidIsValid(new_tablespaceoid) && new_tablespaceoid != MyDatabaseTableSpace)
    {
        AclResult   aclresult;
 
        aclresult = object_aclcheck(TableSpaceRelationId, new_tablespaceoid, GetUserId(),
                                    ACL_CREATE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, OBJECT_TABLESPACE,
                           get_tablespace_name(new_tablespaceoid));
    }
 
    /*
     * Now that the checks are done, check if we should set either to
     * InvalidOid because it is our database's default tablespace.
     */
    if (orig_tablespaceoid == MyDatabaseTableSpace)
        orig_tablespaceoid = InvalidOid;
 
    if (new_tablespaceoid == MyDatabaseTableSpace)
        new_tablespaceoid = InvalidOid;
 
    /* no-op */
    if (orig_tablespaceoid == new_tablespaceoid)
        return new_tablespaceoid;
 
    /*
     * Walk the list of objects in the tablespace and move them. This will
     * only find objects in our database, of course.
     */
    ScanKeyInit(&key[0],
                Anum_pg_class_reltablespace,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(orig_tablespaceoid));
 
    rel = table_open(RelationRelationId, AccessShareLock);
    scan = table_beginscan_catalog(rel, 1, key);
    while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
    {
        Form_pg_class relForm = (Form_pg_class) GETSTRUCT(tuple);
        Oid         relOid = relForm->oid;
 
        /*
         * Do not move objects in pg_catalog as part of this, if an admin
         * really wishes to do so, they can issue the individual ALTER
         * commands directly.
         *
         * Also, explicitly avoid any shared tables, temp tables, or TOAST
         * (TOAST will be moved with the main table).
         */
        if (IsCatalogNamespace(relForm->relnamespace) ||
            relForm->relisshared ||
            isAnyTempNamespace(relForm->relnamespace) ||
            IsToastNamespace(relForm->relnamespace))
            continue;
 
        /* Only move the object type requested */
        if ((stmt->objtype == OBJECT_TABLE &&
             relForm->relkind != RELKIND_RELATION &&
             relForm->relkind != RELKIND_PARTITIONED_TABLE) ||
            (stmt->objtype == OBJECT_INDEX &&
             relForm->relkind != RELKIND_INDEX &&
             relForm->relkind != RELKIND_PARTITIONED_INDEX) ||
            (stmt->objtype == OBJECT_MATVIEW &&
             relForm->relkind != RELKIND_MATVIEW))
            continue;
 
        /* Check if we are only moving objects owned by certain roles */
        if (role_oids != NIL && !list_member_oid(role_oids, relForm->relowner))
            continue;
 
        /*
         * Handle permissions-checking here since we are locking the tables
         * and also to avoid doing a bunch of work only to fail part-way. Note
         * that permissions will also be checked by AlterTableInternal().
         *
         * Caller must be considered an owner on the table to move it.
         */
        if (!object_ownercheck(RelationRelationId, relOid, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relOid)),
                           NameStr(relForm->relname));
 
        if (stmt->nowait &&
            !ConditionalLockRelationOid(relOid, AccessExclusiveLock))
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_IN_USE),
                     errmsg("aborting because lock on relation \"%s.%s\" is not available",
                            get_namespace_name(relForm->relnamespace),
                            NameStr(relForm->relname))));
        else
            LockRelationOid(relOid, AccessExclusiveLock);
 
        /* Add to our list of objects to move */
        relations = lappend_oid(relations, relOid);
    }
 
    table_endscan(scan);
    table_close(rel, AccessShareLock);
 
    if (relations == NIL)
        ereport(NOTICE,
                (errcode(ERRCODE_NO_DATA_FOUND),
                 errmsg("no matching relations in tablespace \"%s\" found",
                        orig_tablespaceoid == InvalidOid ? "(database default)" :
                        get_tablespace_name(orig_tablespaceoid))));
 
    /* Everything is locked, loop through and move all of the relations. */
    foreach(l, relations)
    {
        List       *cmds = NIL;
        AlterTableCmd *cmd = makeNode(AlterTableCmd);
 
        cmd->subtype = AT_SetTableSpace;
        cmd->name = stmt->new_tablespacename;
 
        cmds = lappend(cmds, cmd);
 
        EventTriggerAlterTableStart((Node *) stmt);
        /* OID is set by AlterTableInternal */
        AlterTableInternal(lfirst_oid(l), cmds, false);
        EventTriggerAlterTableEnd();
    }
 
    return new_tablespaceoid;
}
 
static void
index_copy_data(Relation rel, RelFileLocator newrlocator)
{
    SMgrRelation dstrel;
 
    /*
     * Since we copy the file directly without looking at the shared buffers,
     * we'd better first flush out any pages of the source relation that are
     * in shared buffers.  We assume no new changes will be made while we are
     * holding exclusive lock on the rel.
     */
    FlushRelationBuffers(rel);
 
    /*
     * Create and copy all forks of the relation, and schedule unlinking of
     * old physical files.
     *
     * NOTE: any conflict in relfilenumber value will be caught in
     * RelationCreateStorage().
     */
    dstrel = RelationCreateStorage(newrlocator, rel->rd_rel->relpersistence, true);
 
    /* copy main fork */
    RelationCopyStorage(RelationGetSmgr(rel), dstrel, MAIN_FORKNUM,
                        rel->rd_rel->relpersistence);
 
    /* copy those extra forks that exist */
    for (ForkNumber forkNum = MAIN_FORKNUM + 1;
         forkNum <= MAX_FORKNUM; forkNum++)
    {
        if (smgrexists(RelationGetSmgr(rel), forkNum))
        {
            smgrcreate(dstrel, forkNum, false);
 
            /*
             * WAL log creation if the relation is persistent, or this is the
             * init fork of an unlogged relation.
             */
            if (RelationIsPermanent(rel) ||
                (rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED &&
                 forkNum == INIT_FORKNUM))
                log_smgrcreate(&newrlocator, forkNum);
            RelationCopyStorage(RelationGetSmgr(rel), dstrel, forkNum,
                                rel->rd_rel->relpersistence);
        }
    }
 
    /* drop old relation, and close new one */
    RelationDropStorage(rel);
    smgrclose(dstrel);
}
 
/*
 * ALTER TABLE ENABLE/DISABLE TRIGGER
 *
 * We just pass this off to trigger.c.
 */
static void
ATExecEnableDisableTrigger(Relation rel, const char *trigname,
                           char fires_when, bool skip_system, bool recurse,
                           LOCKMODE lockmode)
{
    EnableDisableTrigger(rel, trigname, InvalidOid,
                         fires_when, skip_system, recurse,
                         lockmode);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), 0);
}
 
/*
 * ALTER TABLE ENABLE/DISABLE RULE
 *
 * We just pass this off to rewriteDefine.c.
 */
static void
ATExecEnableDisableRule(Relation rel, const char *rulename,
                        char fires_when, LOCKMODE lockmode)
{
    EnableDisableRule(rel, rulename, fires_when);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), 0);
}
 
/*
 * ALTER TABLE INHERIT
 *
 * Add a parent to the child's parents. This verifies that all the columns and
 * check constraints of the parent appear in the child and that they have the
 * same data types and expressions.
 */
static void
ATPrepAddInherit(Relation child_rel)
{
    if (child_rel->rd_rel->reloftype)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot change inheritance of typed table")));
 
    if (child_rel->rd_rel->relispartition)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot change inheritance of a partition")));
 
    if (child_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot change inheritance of partitioned table")));
}
 
/*
 * Return the address of the new parent relation.
 */
static ObjectAddress
ATExecAddInherit(Relation child_rel, RangeVar *parent, LOCKMODE lockmode)
{
    Relation    parent_rel;
    List       *children;
    ObjectAddress address;
    const char *trigger_name;
 
    /*
     * A self-exclusive lock is needed here.  See the similar case in
     * MergeAttributes() for a full explanation.
     */
    parent_rel = table_openrv(parent, ShareUpdateExclusiveLock);
 
    /*
     * Must be owner of both parent and child -- child was checked by
     * ATSimplePermissions call in ATPrepCmd
     */
    ATSimplePermissions(AT_AddInherit, parent_rel,
                        ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
 
    /* Permanent rels cannot inherit from temporary ones */
    if (parent_rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
        child_rel->rd_rel->relpersistence != RELPERSISTENCE_TEMP)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot inherit from temporary relation \"%s\"",
                        RelationGetRelationName(parent_rel))));
 
    /* If parent rel is temp, it must belong to this session */
    if (parent_rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
        !parent_rel->rd_islocaltemp)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot inherit from temporary relation of another session")));
 
    /* Ditto for the child */
    if (child_rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
        !child_rel->rd_islocaltemp)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot inherit to temporary relation of another session")));
 
    /* Prevent partitioned tables from becoming inheritance parents */
    if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot inherit from partitioned table \"%s\"",
                        parent->relname)));
 
    /* Likewise for partitions */
    if (parent_rel->rd_rel->relispartition)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot inherit from a partition")));
 
    /*
     * Prevent circularity by seeing if proposed parent inherits from child.
     * (In particular, this disallows making a rel inherit from itself.)
     *
     * This is not completely bulletproof because of race conditions: in
     * multi-level inheritance trees, someone else could concurrently be
     * making another inheritance link that closes the loop but does not join
     * either of the rels we have locked.  Preventing that seems to require
     * exclusive locks on the entire inheritance tree, which is a cure worse
     * than the disease.  find_all_inheritors() will cope with circularity
     * anyway, so don't sweat it too much.
     *
     * We use weakest lock we can on child's children, namely AccessShareLock.
     */
    children = find_all_inheritors(RelationGetRelid(child_rel),
                                   AccessShareLock, NULL);
 
    if (list_member_oid(children, RelationGetRelid(parent_rel)))
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_TABLE),
                 errmsg("circular inheritance not allowed"),
                 errdetail("\"%s\" is already a child of \"%s\".",
                           parent->relname,
                           RelationGetRelationName(child_rel))));
 
    /*
     * If child_rel has row-level triggers with transition tables, we
     * currently don't allow it to become an inheritance child.  See also
     * prohibitions in ATExecAttachPartition() and CreateTrigger().
     */
    trigger_name = FindTriggerIncompatibleWithInheritance(child_rel->trigdesc);
    if (trigger_name != NULL)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("trigger \"%s\" prevents table \"%s\" from becoming an inheritance child",
                        trigger_name, RelationGetRelationName(child_rel)),
                 errdetail("ROW triggers with transition tables are not supported in inheritance hierarchies.")));
 
    /* OK to create inheritance */
    CreateInheritance(child_rel, parent_rel, false);
 
    ObjectAddressSet(address, RelationRelationId,
                     RelationGetRelid(parent_rel));
 
    /* keep our lock on the parent relation until commit */
    table_close(parent_rel, NoLock);
 
    return address;
}
 
/*
 * CreateInheritance
 *      Catalog manipulation portion of creating inheritance between a child
 *      table and a parent table.
 *
 * Common to ATExecAddInherit() and ATExecAttachPartition().
 */
static void
CreateInheritance(Relation child_rel, Relation parent_rel, bool ispartition)
{
    Relation    catalogRelation;
    SysScanDesc scan;
    ScanKeyData key;
    HeapTuple   inheritsTuple;
    int32       inhseqno;
 
    /* Note: get RowExclusiveLock because we will write pg_inherits below. */
    catalogRelation = table_open(InheritsRelationId, RowExclusiveLock);
 
    /*
     * Check for duplicates in the list of parents, and determine the highest
     * inhseqno already present; we'll use the next one for the new parent.
     * Also, if proposed child is a partition, it cannot already be
     * inheriting.
     *
     * Note: we do not reject the case where the child already inherits from
     * the parent indirectly; CREATE TABLE doesn't reject comparable cases.
     */
    ScanKeyInit(&key,
                Anum_pg_inherits_inhrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(child_rel)));
    scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId,
                              true, NULL, 1, &key);
 
    /* inhseqno sequences start at 1 */
    inhseqno = 0;
    while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
    {
        Form_pg_inherits inh = (Form_pg_inherits) GETSTRUCT(inheritsTuple);
 
        if (inh->inhparent == RelationGetRelid(parent_rel))
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_TABLE),
                     errmsg("relation \"%s\" would be inherited from more than once",
                            RelationGetRelationName(parent_rel))));
 
        if (inh->inhseqno > inhseqno)
            inhseqno = inh->inhseqno;
    }
    systable_endscan(scan);
 
    /* Match up the columns and bump attinhcount as needed */
    MergeAttributesIntoExisting(child_rel, parent_rel, ispartition);
 
    /* Match up the constraints and bump coninhcount as needed */
    MergeConstraintsIntoExisting(child_rel, parent_rel);
 
    /*
     * OK, it looks valid.  Make the catalog entries that show inheritance.
     */
    StoreCatalogInheritance1(RelationGetRelid(child_rel),
                             RelationGetRelid(parent_rel),
                             inhseqno + 1,
                             catalogRelation,
                             parent_rel->rd_rel->relkind ==
                             RELKIND_PARTITIONED_TABLE);
 
    /* Now we're done with pg_inherits */
    table_close(catalogRelation, RowExclusiveLock);
}
 
/*
 * Obtain the source-text form of the constraint expression for a check
 * constraint, given its pg_constraint tuple
 */
static char *
decompile_conbin(HeapTuple contup, TupleDesc tupdesc)
{
    Form_pg_constraint con;
    bool        isnull;
    Datum       attr;
    Datum       expr;
 
    con = (Form_pg_constraint) GETSTRUCT(contup);
    attr = heap_getattr(contup, Anum_pg_constraint_conbin, tupdesc, &isnull);
    if (isnull)
        elog(ERROR, "null conbin for constraint %u", con->oid);
 
    expr = DirectFunctionCall2(pg_get_expr, attr,
                               ObjectIdGetDatum(con->conrelid));
    return TextDatumGetCString(expr);
}
 
/*
 * Determine whether two check constraints are functionally equivalent
 *
 * The test we apply is to see whether they reverse-compile to the same
 * source string.  This insulates us from issues like whether attributes
 * have the same physical column numbers in parent and child relations.
 */
static bool
constraints_equivalent(HeapTuple a, HeapTuple b, TupleDesc tupleDesc)
{
    Form_pg_constraint acon = (Form_pg_constraint) GETSTRUCT(a);
    Form_pg_constraint bcon = (Form_pg_constraint) GETSTRUCT(b);
 
    if (acon->condeferrable != bcon->condeferrable ||
        acon->condeferred != bcon->condeferred ||
        strcmp(decompile_conbin(a, tupleDesc),
               decompile_conbin(b, tupleDesc)) != 0)
        return false;
    else
        return true;
}
 
/*
 * Check columns in child table match up with columns in parent, and increment
 * their attinhcount.
 *
 * Called by CreateInheritance
 *
 * Currently all parent columns must be found in child. Missing columns are an
 * error.  One day we might consider creating new columns like CREATE TABLE
 * does.  However, that is widely unpopular --- in the common use case of
 * partitioned tables it's a foot-gun.
 *
 * The data type must match exactly. If the parent column is NOT NULL then
 * the child must be as well. Defaults are not compared, however.
 */
static void
MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel, bool ispartition)
{
    Relation    attrrel;
    TupleDesc   parent_desc;
 
    attrrel = table_open(AttributeRelationId, RowExclusiveLock);
    parent_desc = RelationGetDescr(parent_rel);
 
    for (AttrNumber parent_attno = 1; parent_attno <= parent_desc->natts; parent_attno++)
    {
        Form_pg_attribute parent_att = TupleDescAttr(parent_desc, parent_attno - 1);
        char       *parent_attname = NameStr(parent_att->attname);
        HeapTuple   tuple;
 
        /* Ignore dropped columns in the parent. */
        if (parent_att->attisdropped)
            continue;
 
        /* Find same column in child (matching on column name). */
        tuple = SearchSysCacheCopyAttName(RelationGetRelid(child_rel), parent_attname);
        if (HeapTupleIsValid(tuple))
        {
            Form_pg_attribute child_att = (Form_pg_attribute) GETSTRUCT(tuple);
 
            if (parent_att->atttypid != child_att->atttypid ||
                parent_att->atttypmod != child_att->atttypmod)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("child table \"%s\" has different type for column \"%s\"",
                                RelationGetRelationName(child_rel), parent_attname)));
 
            if (parent_att->attcollation != child_att->attcollation)
                ereport(ERROR,
                        (errcode(ERRCODE_COLLATION_MISMATCH),
                         errmsg("child table \"%s\" has different collation for column \"%s\"",
                                RelationGetRelationName(child_rel), parent_attname)));
 
            /*
             * Check child doesn't discard NOT NULL property.  (Other
             * constraints are checked elsewhere.)
             */
            if (parent_att->attnotnull && !child_att->attnotnull)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("column \"%s\" in child table must be marked NOT NULL",
                                parent_attname)));
 
            /*
             * Child column must be generated if and only if parent column is.
             */
            if (parent_att->attgenerated && !child_att->attgenerated)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("column \"%s\" in child table must be a generated column", parent_attname)));
            if (child_att->attgenerated && !parent_att->attgenerated)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("column \"%s\" in child table must not be a generated column", parent_attname)));
 
            /*
             * Regular inheritance children are independent enough not to
             * inherit identity columns.  But partitions are integral part of
             * a partitioned table and inherit identity column.
             */
            if (ispartition)
                child_att->attidentity = parent_att->attidentity;
 
            /*
             * OK, bump the child column's inheritance count.  (If we fail
             * later on, this change will just roll back.)
             */
            if (pg_add_s16_overflow(child_att->attinhcount, 1,
                                    &child_att->attinhcount))
                ereport(ERROR,
                        errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                        errmsg("too many inheritance parents"));
 
            /*
             * In case of partitions, we must enforce that value of attislocal
             * is same in all partitions. (Note: there are only inherited
             * attributes in partitions)
             */
            if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
            {
                Assert(child_att->attinhcount == 1);
                child_att->attislocal = false;
            }
 
            CatalogTupleUpdate(attrrel, &tuple->t_self, tuple);
            heap_freetuple(tuple);
        }
        else
        {
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("child table is missing column \"%s\"", parent_attname)));
        }
    }
 
    table_close(attrrel, RowExclusiveLock);
}
 
/*
 * Check constraints in child table match up with constraints in parent,
 * and increment their coninhcount.
 *
 * Constraints that are marked ONLY in the parent are ignored.
 *
 * Called by CreateInheritance
 *
 * Currently all constraints in parent must be present in the child. One day we
 * may consider adding new constraints like CREATE TABLE does.
 *
 * XXX This is O(N^2) which may be an issue with tables with hundreds of
 * constraints. As long as tables have more like 10 constraints it shouldn't be
 * a problem though. Even 100 constraints ought not be the end of the world.
 *
 * XXX See MergeWithExistingConstraint too if you change this code.
 */
static void
MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
{
    Relation    constraintrel;
    SysScanDesc parent_scan;
    ScanKeyData parent_key;
    HeapTuple   parent_tuple;
    Oid         parent_relid = RelationGetRelid(parent_rel);
 
    constraintrel = table_open(ConstraintRelationId, RowExclusiveLock);
 
    /* Outer loop scans through the parent's constraint definitions */
    ScanKeyInit(&parent_key,
                Anum_pg_constraint_conrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(parent_relid));
    parent_scan = systable_beginscan(constraintrel, ConstraintRelidTypidNameIndexId,
                                     true, NULL, 1, &parent_key);
 
    while (HeapTupleIsValid(parent_tuple = systable_getnext(parent_scan)))
    {
        Form_pg_constraint parent_con = (Form_pg_constraint) GETSTRUCT(parent_tuple);
        SysScanDesc child_scan;
        ScanKeyData child_key;
        HeapTuple   child_tuple;
        bool        found = false;
 
        if (parent_con->contype != CONSTRAINT_CHECK)
            continue;
 
        /* if the parent's constraint is marked NO INHERIT, it's not inherited */
        if (parent_con->connoinherit)
            continue;
 
        /* Search for a child constraint matching this one */
        ScanKeyInit(&child_key,
                    Anum_pg_constraint_conrelid,
                    BTEqualStrategyNumber, F_OIDEQ,
                    ObjectIdGetDatum(RelationGetRelid(child_rel)));
        child_scan = systable_beginscan(constraintrel, ConstraintRelidTypidNameIndexId,
                                        true, NULL, 1, &child_key);
 
        while (HeapTupleIsValid(child_tuple = systable_getnext(child_scan)))
        {
            Form_pg_constraint child_con = (Form_pg_constraint) GETSTRUCT(child_tuple);
            HeapTuple   child_copy;
 
            if (child_con->contype != CONSTRAINT_CHECK)
                continue;
 
            if (strcmp(NameStr(parent_con->conname),
                       NameStr(child_con->conname)) != 0)
                continue;
 
            if (!constraints_equivalent(parent_tuple, child_tuple, RelationGetDescr(constraintrel)))
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("child table \"%s\" has different definition for check constraint \"%s\"",
                                RelationGetRelationName(child_rel), NameStr(parent_con->conname))));
 
            /* If the child constraint is "no inherit" then cannot merge */
            if (child_con->connoinherit)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("constraint \"%s\" conflicts with non-inherited constraint on child table \"%s\"",
                                NameStr(child_con->conname), RelationGetRelationName(child_rel))));
 
            /*
             * If the child constraint is "not valid" then cannot merge with a
             * valid parent constraint
             */
            if (parent_con->convalidated && !child_con->convalidated)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("constraint \"%s\" conflicts with NOT VALID constraint on child table \"%s\"",
                                NameStr(child_con->conname), RelationGetRelationName(child_rel))));
 
            /*
             * OK, bump the child constraint's inheritance count.  (If we fail
             * later on, this change will just roll back.)
             */
            child_copy = heap_copytuple(child_tuple);
            child_con = (Form_pg_constraint) GETSTRUCT(child_copy);
 
            if (pg_add_s16_overflow(child_con->coninhcount, 1,
                                    &child_con->coninhcount))
                ereport(ERROR,
                        errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                        errmsg("too many inheritance parents"));
 
            /*
             * In case of partitions, an inherited constraint must be
             * inherited only once since it cannot have multiple parents and
             * it is never considered local.
             */
            if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
            {
                Assert(child_con->coninhcount == 1);
                child_con->conislocal = false;
            }
 
            CatalogTupleUpdate(constraintrel, &child_copy->t_self, child_copy);
            heap_freetuple(child_copy);
 
            found = true;
            break;
        }
 
        systable_endscan(child_scan);
 
        if (!found)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("child table is missing constraint \"%s\"",
                            NameStr(parent_con->conname))));
    }
 
    systable_endscan(parent_scan);
    table_close(constraintrel, RowExclusiveLock);
}
 
/*
 * ALTER TABLE NO INHERIT
 *
 * Return value is the address of the relation that is no longer parent.
 */
static ObjectAddress
ATExecDropInherit(Relation rel, RangeVar *parent, LOCKMODE lockmode)
{
    ObjectAddress address;
    Relation    parent_rel;
 
    if (rel->rd_rel->relispartition)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot change inheritance of a partition")));
 
    /*
     * AccessShareLock on the parent is probably enough, seeing that DROP
     * TABLE doesn't lock parent tables at all.  We need some lock since we'll
     * be inspecting the parent's schema.
     */
    parent_rel = table_openrv(parent, AccessShareLock);
 
    /*
     * We don't bother to check ownership of the parent table --- ownership of
     * the child is presumed enough rights.
     */
 
    /* Off to RemoveInheritance() where most of the work happens */
    RemoveInheritance(rel, parent_rel, false);
 
    ObjectAddressSet(address, RelationRelationId,
                     RelationGetRelid(parent_rel));
 
    /* keep our lock on the parent relation until commit */
    table_close(parent_rel, NoLock);
 
    return address;
}
 
/*
 * MarkInheritDetached
 *
 * Set inhdetachpending for a partition, for ATExecDetachPartition
 * in concurrent mode.  While at it, verify that no other partition is
 * already pending detach.
 */
static void
MarkInheritDetached(Relation child_rel, Relation parent_rel)
{
    Relation    catalogRelation;
    SysScanDesc scan;
    ScanKeyData key;
    HeapTuple   inheritsTuple;
    bool        found = false;
 
    Assert(parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
    /*
     * Find pg_inherits entries by inhparent.  (We need to scan them all in
     * order to verify that no other partition is pending detach.)
     */
    catalogRelation = table_open(InheritsRelationId, RowExclusiveLock);
    ScanKeyInit(&key,
                Anum_pg_inherits_inhparent,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(parent_rel)));
    scan = systable_beginscan(catalogRelation, InheritsParentIndexId,
                              true, NULL, 1, &key);
 
    while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
    {
        Form_pg_inherits inhForm;
 
        inhForm = (Form_pg_inherits) GETSTRUCT(inheritsTuple);
        if (inhForm->inhdetachpending)
            ereport(ERROR,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("partition \"%s\" already pending detach in partitioned table \"%s.%s\"",
                           get_rel_name(inhForm->inhrelid),
                           get_namespace_name(parent_rel->rd_rel->relnamespace),
                           RelationGetRelationName(parent_rel)),
                    errhint("Use ALTER TABLE ... DETACH PARTITION ... FINALIZE to complete the pending detach operation."));
 
        if (inhForm->inhrelid == RelationGetRelid(child_rel))
        {
            HeapTuple   newtup;
 
            newtup = heap_copytuple(inheritsTuple);
            ((Form_pg_inherits) GETSTRUCT(newtup))->inhdetachpending = true;
 
            CatalogTupleUpdate(catalogRelation,
                               &inheritsTuple->t_self,
                               newtup);
            found = true;
            heap_freetuple(newtup);
            /* keep looking, to ensure we catch others pending detach */
        }
    }
 
    /* Done */
    systable_endscan(scan);
    table_close(catalogRelation, RowExclusiveLock);
 
    if (!found)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_TABLE),
                 errmsg("relation \"%s\" is not a partition of relation \"%s\"",
                        RelationGetRelationName(child_rel),
                        RelationGetRelationName(parent_rel))));
}
 
/*
 * RemoveInheritance
 *
 * Drop a parent from the child's parents. This just adjusts the attinhcount
 * and attislocal of the columns and removes the pg_inherit and pg_depend
 * entries.  expect_detached is passed down to DeleteInheritsTuple, q.v..
 *
 * If attinhcount goes to 0 then attislocal gets set to true. If it goes back
 * up attislocal stays true, which means if a child is ever removed from a
 * parent then its columns will never be automatically dropped which may
 * surprise. But at least we'll never surprise by dropping columns someone
 * isn't expecting to be dropped which would actually mean data loss.
 *
 * coninhcount and conislocal for inherited constraints are adjusted in
 * exactly the same way.
 *
 * Common to ATExecDropInherit() and ATExecDetachPartition().
 */
static void
RemoveInheritance(Relation child_rel, Relation parent_rel, bool expect_detached)
{
    Relation    catalogRelation;
    SysScanDesc scan;
    ScanKeyData key[3];
    HeapTuple   attributeTuple,
                constraintTuple;
    List       *connames;
    bool        found;
    bool        is_partitioning;
 
    is_partitioning = (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
    found = DeleteInheritsTuple(RelationGetRelid(child_rel),
                                RelationGetRelid(parent_rel),
                                expect_detached,
                                RelationGetRelationName(child_rel));
    if (!found)
    {
        if (is_partitioning)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_TABLE),
                     errmsg("relation \"%s\" is not a partition of relation \"%s\"",
                            RelationGetRelationName(child_rel),
                            RelationGetRelationName(parent_rel))));
        else
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_TABLE),
                     errmsg("relation \"%s\" is not a parent of relation \"%s\"",
                            RelationGetRelationName(parent_rel),
                            RelationGetRelationName(child_rel))));
    }
 
    /*
     * Search through child columns looking for ones matching parent rel
     */
    catalogRelation = table_open(AttributeRelationId, RowExclusiveLock);
    ScanKeyInit(&key[0],
                Anum_pg_attribute_attrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(child_rel)));
    scan = systable_beginscan(catalogRelation, AttributeRelidNumIndexId,
                              true, NULL, 1, key);
    while (HeapTupleIsValid(attributeTuple = systable_getnext(scan)))
    {
        Form_pg_attribute att = (Form_pg_attribute) GETSTRUCT(attributeTuple);
 
        /* Ignore if dropped or not inherited */
        if (att->attisdropped)
            continue;
        if (att->attinhcount <= 0)
            continue;
 
        if (SearchSysCacheExistsAttName(RelationGetRelid(parent_rel),
                                        NameStr(att->attname)))
        {
            /* Decrement inhcount and possibly set islocal to true */
            HeapTuple   copyTuple = heap_copytuple(attributeTuple);
            Form_pg_attribute copy_att = (Form_pg_attribute) GETSTRUCT(copyTuple);
 
            copy_att->attinhcount--;
            if (copy_att->attinhcount == 0)
                copy_att->attislocal = true;
 
            CatalogTupleUpdate(catalogRelation, &copyTuple->t_self, copyTuple);
            heap_freetuple(copyTuple);
        }
    }
    systable_endscan(scan);
    table_close(catalogRelation, RowExclusiveLock);
 
    /*
     * Likewise, find inherited check constraints and disinherit them. To do
     * this, we first need a list of the names of the parent's check
     * constraints.  (We cheat a bit by only checking for name matches,
     * assuming that the expressions will match.)
     */
    catalogRelation = table_open(ConstraintRelationId, RowExclusiveLock);
    ScanKeyInit(&key[0],
                Anum_pg_constraint_conrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(parent_rel)));
    scan = systable_beginscan(catalogRelation, ConstraintRelidTypidNameIndexId,
                              true, NULL, 1, key);
 
    connames = NIL;
 
    while (HeapTupleIsValid(constraintTuple = systable_getnext(scan)))
    {
        Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(constraintTuple);
 
        if (con->contype == CONSTRAINT_CHECK)
            connames = lappend(connames, pstrdup(NameStr(con->conname)));
    }
 
    systable_endscan(scan);
 
    /* Now scan the child's constraints */
    ScanKeyInit(&key[0],
                Anum_pg_constraint_conrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(child_rel)));
    scan = systable_beginscan(catalogRelation, ConstraintRelidTypidNameIndexId,
                              true, NULL, 1, key);
 
    while (HeapTupleIsValid(constraintTuple = systable_getnext(scan)))
    {
        Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(constraintTuple);
        bool        match;
 
        if (con->contype != CONSTRAINT_CHECK)
            continue;
 
        match = false;
        foreach_ptr(char, chkname, connames)
        {
            if (strcmp(NameStr(con->conname), chkname) == 0)
            {
                match = true;
                break;
            }
        }
 
        if (match)
        {
            /* Decrement inhcount and possibly set islocal to true */
            HeapTuple   copyTuple = heap_copytuple(constraintTuple);
            Form_pg_constraint copy_con = (Form_pg_constraint) GETSTRUCT(copyTuple);
 
            if (copy_con->coninhcount <= 0) /* shouldn't happen */
                elog(ERROR, "relation %u has non-inherited constraint \"%s\"",
                     RelationGetRelid(child_rel), NameStr(copy_con->conname));
 
            copy_con->coninhcount--;
            if (copy_con->coninhcount == 0)
                copy_con->conislocal = true;
 
            CatalogTupleUpdate(catalogRelation, &copyTuple->t_self, copyTuple);
            heap_freetuple(copyTuple);
        }
    }
 
    systable_endscan(scan);
    table_close(catalogRelation, RowExclusiveLock);
 
    drop_parent_dependency(RelationGetRelid(child_rel),
                           RelationRelationId,
                           RelationGetRelid(parent_rel),
                           child_dependency_type(is_partitioning));
 
    /*
     * Post alter hook of this inherits. Since object_access_hook doesn't take
     * multiple object identifiers, we relay oid of parent relation using
     * auxiliary_id argument.
     */
    InvokeObjectPostAlterHookArg(InheritsRelationId,
                                 RelationGetRelid(child_rel), 0,
                                 RelationGetRelid(parent_rel), false);
}
 
/*
 * Drop the dependency created by StoreCatalogInheritance1 (CREATE TABLE
 * INHERITS/ALTER TABLE INHERIT -- refclassid will be RelationRelationId) or
 * heap_create_with_catalog (CREATE TABLE OF/ALTER TABLE OF -- refclassid will
 * be TypeRelationId).  There's no convenient way to do this, so go trawling
 * through pg_depend.
 */
static void
drop_parent_dependency(Oid relid, Oid refclassid, Oid refobjid,
                       DependencyType deptype)
{
    Relation    catalogRelation;
    SysScanDesc scan;
    ScanKeyData key[3];
    HeapTuple   depTuple;
 
    catalogRelation = table_open(DependRelationId, RowExclusiveLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_depend_classid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationRelationId));
    ScanKeyInit(&key[1],
                Anum_pg_depend_objid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relid));
    ScanKeyInit(&key[2],
                Anum_pg_depend_objsubid,
                BTEqualStrategyNumber, F_INT4EQ,
                Int32GetDatum(0));
 
    scan = systable_beginscan(catalogRelation, DependDependerIndexId, true,
                              NULL, 3, key);
 
    while (HeapTupleIsValid(depTuple = systable_getnext(scan)))
    {
        Form_pg_depend dep = (Form_pg_depend) GETSTRUCT(depTuple);
 
        if (dep->refclassid == refclassid &&
            dep->refobjid == refobjid &&
            dep->refobjsubid == 0 &&
            dep->deptype == deptype)
            CatalogTupleDelete(catalogRelation, &depTuple->t_self);
    }
 
    systable_endscan(scan);
    table_close(catalogRelation, RowExclusiveLock);
}
 
/*
 * ALTER TABLE OF
 *
 * Attach a table to a composite type, as though it had been created with CREATE
 * TABLE OF.  All attname, atttypid, atttypmod and attcollation must match.  The
 * subject table must not have inheritance parents.  These restrictions ensure
 * that you cannot create a configuration impossible with CREATE TABLE OF alone.
 *
 * The address of the type is returned.
 */
static ObjectAddress
ATExecAddOf(Relation rel, const TypeName *ofTypename, LOCKMODE lockmode)
{
    Oid         relid = RelationGetRelid(rel);
    Type        typetuple;
    Form_pg_type typeform;
    Oid         typeid;
    Relation    inheritsRelation,
                relationRelation;
    SysScanDesc scan;
    ScanKeyData key;
    AttrNumber  table_attno,
                type_attno;
    TupleDesc   typeTupleDesc,
                tableTupleDesc;
    ObjectAddress tableobj,
                typeobj;
    HeapTuple   classtuple;
 
    /* Validate the type. */
    typetuple = typenameType(NULL, ofTypename, NULL);
    check_of_type(typetuple);
    typeform = (Form_pg_type) GETSTRUCT(typetuple);
    typeid = typeform->oid;
 
    /* Fail if the table has any inheritance parents. */
    inheritsRelation = table_open(InheritsRelationId, AccessShareLock);
    ScanKeyInit(&key,
                Anum_pg_inherits_inhrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relid));
    scan = systable_beginscan(inheritsRelation, InheritsRelidSeqnoIndexId,
                              true, NULL, 1, &key);
    if (HeapTupleIsValid(systable_getnext(scan)))
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("typed tables cannot inherit")));
    systable_endscan(scan);
    table_close(inheritsRelation, AccessShareLock);
 
    /*
     * Check the tuple descriptors for compatibility.  Unlike inheritance, we
     * require that the order also match.  However, attnotnull need not match.
     */
    typeTupleDesc = lookup_rowtype_tupdesc(typeid, -1);
    tableTupleDesc = RelationGetDescr(rel);
    table_attno = 1;
    for (type_attno = 1; type_attno <= typeTupleDesc->natts; type_attno++)
    {
        Form_pg_attribute type_attr,
                    table_attr;
        const char *type_attname,
                   *table_attname;
 
        /* Get the next non-dropped type attribute. */
        type_attr = TupleDescAttr(typeTupleDesc, type_attno - 1);
        if (type_attr->attisdropped)
            continue;
        type_attname = NameStr(type_attr->attname);
 
        /* Get the next non-dropped table attribute. */
        do
        {
            if (table_attno > tableTupleDesc->natts)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("table is missing column \"%s\"",
                                type_attname)));
            table_attr = TupleDescAttr(tableTupleDesc, table_attno - 1);
            table_attno++;
        } while (table_attr->attisdropped);
        table_attname = NameStr(table_attr->attname);
 
        /* Compare name. */
        if (strncmp(table_attname, type_attname, NAMEDATALEN) != 0)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("table has column \"%s\" where type requires \"%s\"",
                            table_attname, type_attname)));
 
        /* Compare type. */
        if (table_attr->atttypid != type_attr->atttypid ||
            table_attr->atttypmod != type_attr->atttypmod ||
            table_attr->attcollation != type_attr->attcollation)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("table \"%s\" has different type for column \"%s\"",
                            RelationGetRelationName(rel), type_attname)));
    }
    ReleaseTupleDesc(typeTupleDesc);
 
    /* Any remaining columns at the end of the table had better be dropped. */
    for (; table_attno <= tableTupleDesc->natts; table_attno++)
    {
        Form_pg_attribute table_attr = TupleDescAttr(tableTupleDesc,
                                                     table_attno - 1);
 
        if (!table_attr->attisdropped)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("table has extra column \"%s\"",
                            NameStr(table_attr->attname))));
    }
 
    /* If the table was already typed, drop the existing dependency. */
    if (rel->rd_rel->reloftype)
        drop_parent_dependency(relid, TypeRelationId, rel->rd_rel->reloftype,
                               DEPENDENCY_NORMAL);
 
    /* Record a dependency on the new type. */
    tableobj.classId = RelationRelationId;
    tableobj.objectId = relid;
    tableobj.objectSubId = 0;
    typeobj.classId = TypeRelationId;
    typeobj.objectId = typeid;
    typeobj.objectSubId = 0;
    recordDependencyOn(&tableobj, &typeobj, DEPENDENCY_NORMAL);
 
    /* Update pg_class.reloftype */
    relationRelation = table_open(RelationRelationId, RowExclusiveLock);
    classtuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(classtuple))
        elog(ERROR, "cache lookup failed for relation %u", relid);
    ((Form_pg_class) GETSTRUCT(classtuple))->reloftype = typeid;
    CatalogTupleUpdate(relationRelation, &classtuple->t_self, classtuple);
 
    InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
 
    heap_freetuple(classtuple);
    table_close(relationRelation, RowExclusiveLock);
 
    ReleaseSysCache(typetuple);
 
    return typeobj;
}
 
/*
 * ALTER TABLE NOT OF
 *
 * Detach a typed table from its originating type.  Just clear reloftype and
 * remove the dependency.
 */
static void
ATExecDropOf(Relation rel, LOCKMODE lockmode)
{
    Oid         relid = RelationGetRelid(rel);
    Relation    relationRelation;
    HeapTuple   tuple;
 
    if (!OidIsValid(rel->rd_rel->reloftype))
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a typed table",
                        RelationGetRelationName(rel))));
 
    /*
     * We don't bother to check ownership of the type --- ownership of the
     * table is presumed enough rights.  No lock required on the type, either.
     */
 
    drop_parent_dependency(relid, TypeRelationId, rel->rd_rel->reloftype,
                           DEPENDENCY_NORMAL);
 
    /* Clear pg_class.reloftype */
    relationRelation = table_open(RelationRelationId, RowExclusiveLock);
    tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", relid);
    ((Form_pg_class) GETSTRUCT(tuple))->reloftype = InvalidOid;
    CatalogTupleUpdate(relationRelation, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
 
    heap_freetuple(tuple);
    table_close(relationRelation, RowExclusiveLock);
}
 
/*
 * relation_mark_replica_identity: Update a table's replica identity
 *
 * Iff ri_type = REPLICA_IDENTITY_INDEX, indexOid must be the Oid of a suitable
 * index. Otherwise, it must be InvalidOid.
 *
 * Caller had better hold an exclusive lock on the relation, as the results
 * of running two of these concurrently wouldn't be pretty.
 */
static void
relation_mark_replica_identity(Relation rel, char ri_type, Oid indexOid,
                               bool is_internal)
{
    Relation    pg_index;
    Relation    pg_class;
    HeapTuple   pg_class_tuple;
    HeapTuple   pg_index_tuple;
    Form_pg_class pg_class_form;
    Form_pg_index pg_index_form;
    ListCell   *index;
 
    /*
     * Check whether relreplident has changed, and update it if so.
     */
    pg_class = table_open(RelationRelationId, RowExclusiveLock);
    pg_class_tuple = SearchSysCacheCopy1(RELOID,
                                         ObjectIdGetDatum(RelationGetRelid(rel)));
    if (!HeapTupleIsValid(pg_class_tuple))
        elog(ERROR, "cache lookup failed for relation \"%s\"",
             RelationGetRelationName(rel));
    pg_class_form = (Form_pg_class) GETSTRUCT(pg_class_tuple);
    if (pg_class_form->relreplident != ri_type)
    {
        pg_class_form->relreplident = ri_type;
        CatalogTupleUpdate(pg_class, &pg_class_tuple->t_self, pg_class_tuple);
    }
    table_close(pg_class, RowExclusiveLock);
    heap_freetuple(pg_class_tuple);
 
    /*
     * Update the per-index indisreplident flags correctly.
     */
    pg_index = table_open(IndexRelationId, RowExclusiveLock);
    foreach(index, RelationGetIndexList(rel))
    {
        Oid         thisIndexOid = lfirst_oid(index);
        bool        dirty = false;
 
        pg_index_tuple = SearchSysCacheCopy1(INDEXRELID,
                                             ObjectIdGetDatum(thisIndexOid));
        if (!HeapTupleIsValid(pg_index_tuple))
            elog(ERROR, "cache lookup failed for index %u", thisIndexOid);
        pg_index_form = (Form_pg_index) GETSTRUCT(pg_index_tuple);
 
        if (thisIndexOid == indexOid)
        {
            /* Set the bit if not already set. */
            if (!pg_index_form->indisreplident)
            {
                dirty = true;
                pg_index_form->indisreplident = true;
            }
        }
        else
        {
            /* Unset the bit if set. */
            if (pg_index_form->indisreplident)
            {
                dirty = true;
                pg_index_form->indisreplident = false;
            }
        }
 
        if (dirty)
        {
            CatalogTupleUpdate(pg_index, &pg_index_tuple->t_self, pg_index_tuple);
            InvokeObjectPostAlterHookArg(IndexRelationId, thisIndexOid, 0,
                                         InvalidOid, is_internal);
 
            /*
             * Invalidate the relcache for the table, so that after we commit
             * all sessions will refresh the table's replica identity index
             * before attempting any UPDATE or DELETE on the table.  (If we
             * changed the table's pg_class row above, then a relcache inval
             * is already queued due to that; but we might not have.)
             */
            CacheInvalidateRelcache(rel);
        }
        heap_freetuple(pg_index_tuple);
    }
 
    table_close(pg_index, RowExclusiveLock);
}
 
/*
 * ALTER TABLE <name> REPLICA IDENTITY ...
 */
static void
ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKMODE lockmode)
{
    Oid         indexOid;
    Relation    indexRel;
    int         key;
 
    if (stmt->identity_type == REPLICA_IDENTITY_DEFAULT)
    {
        relation_mark_replica_identity(rel, stmt->identity_type, InvalidOid, true);
        return;
    }
    else if (stmt->identity_type == REPLICA_IDENTITY_FULL)
    {
        relation_mark_replica_identity(rel, stmt->identity_type, InvalidOid, true);
        return;
    }
    else if (stmt->identity_type == REPLICA_IDENTITY_NOTHING)
    {
        relation_mark_replica_identity(rel, stmt->identity_type, InvalidOid, true);
        return;
    }
    else if (stmt->identity_type == REPLICA_IDENTITY_INDEX)
    {
         /* fallthrough */ ;
    }
    else
        elog(ERROR, "unexpected identity type %u", stmt->identity_type);
 
    /* Check that the index exists */
    indexOid = get_relname_relid(stmt->name, rel->rd_rel->relnamespace);
    if (!OidIsValid(indexOid))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("index \"%s\" for table \"%s\" does not exist",
                        stmt->name, RelationGetRelationName(rel))));
 
    indexRel = index_open(indexOid, ShareLock);
 
    /* Check that the index is on the relation we're altering. */
    if (indexRel->rd_index == NULL ||
        indexRel->rd_index->indrelid != RelationGetRelid(rel))
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not an index for table \"%s\"",
                        RelationGetRelationName(indexRel),
                        RelationGetRelationName(rel))));
    /* The AM must support uniqueness, and the index must in fact be unique. */
    if (!indexRel->rd_indam->amcanunique ||
        !indexRel->rd_index->indisunique)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot use non-unique index \"%s\" as replica identity",
                        RelationGetRelationName(indexRel))));
    /* Deferred indexes are not guaranteed to be always unique. */
    if (!indexRel->rd_index->indimmediate)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot use non-immediate index \"%s\" as replica identity",
                        RelationGetRelationName(indexRel))));
    /* Expression indexes aren't supported. */
    if (RelationGetIndexExpressions(indexRel) != NIL)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot use expression index \"%s\" as replica identity",
                        RelationGetRelationName(indexRel))));
    /* Predicate indexes aren't supported. */
    if (RelationGetIndexPredicate(indexRel) != NIL)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot use partial index \"%s\" as replica identity",
                        RelationGetRelationName(indexRel))));
 
    /* Check index for nullable columns. */
    for (key = 0; key < IndexRelationGetNumberOfKeyAttributes(indexRel); key++)
    {
        int16       attno = indexRel->rd_index->indkey.values[key];
        Form_pg_attribute attr;
 
        /*
         * Reject any other system columns.  (Going forward, we'll disallow
         * indexes containing such columns in the first place, but they might
         * exist in older branches.)
         */
        if (attno <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
                     errmsg("index \"%s\" cannot be used as replica identity because column %d is a system column",
                            RelationGetRelationName(indexRel), attno)));
 
        attr = TupleDescAttr(rel->rd_att, attno - 1);
        if (!attr->attnotnull)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("index \"%s\" cannot be used as replica identity because column \"%s\" is nullable",
                            RelationGetRelationName(indexRel),
                            NameStr(attr->attname))));
    }
 
    /* This index is suitable for use as a replica identity. Mark it. */
    relation_mark_replica_identity(rel, stmt->identity_type, indexOid, true);
 
    index_close(indexRel, NoLock);
}
 
/*
 * ALTER TABLE ENABLE/DISABLE ROW LEVEL SECURITY
 */
static void
ATExecSetRowSecurity(Relation rel, bool rls)
{
    Relation    pg_class;
    Oid         relid;
    HeapTuple   tuple;
 
    relid = RelationGetRelid(rel);
 
    /* Pull the record for this relation and update it */
    pg_class = table_open(RelationRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
 
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", relid);
 
    ((Form_pg_class) GETSTRUCT(tuple))->relrowsecurity = rls;
    CatalogTupleUpdate(pg_class, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), 0);
 
    table_close(pg_class, RowExclusiveLock);
    heap_freetuple(tuple);
}
 
/*
 * ALTER TABLE FORCE/NO FORCE ROW LEVEL SECURITY
 */
static void
ATExecForceNoForceRowSecurity(Relation rel, bool force_rls)
{
    Relation    pg_class;
    Oid         relid;
    HeapTuple   tuple;
 
    relid = RelationGetRelid(rel);
 
    pg_class = table_open(RelationRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
 
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", relid);
 
    ((Form_pg_class) GETSTRUCT(tuple))->relforcerowsecurity = force_rls;
    CatalogTupleUpdate(pg_class, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel), 0);
 
    table_close(pg_class, RowExclusiveLock);
    heap_freetuple(tuple);
}
 
/*
 * ALTER FOREIGN TABLE <name> OPTIONS (...)
 */
static void
ATExecGenericOptions(Relation rel, List *options)
{
    Relation    ftrel;
    ForeignServer *server;
    ForeignDataWrapper *fdw;
    HeapTuple   tuple;
    bool        isnull;
    Datum       repl_val[Natts_pg_foreign_table];
    bool        repl_null[Natts_pg_foreign_table];
    bool        repl_repl[Natts_pg_foreign_table];
    Datum       datum;
    Form_pg_foreign_table tableform;
 
    if (options == NIL)
        return;
 
    ftrel = table_open(ForeignTableRelationId, RowExclusiveLock);
 
    tuple = SearchSysCacheCopy1(FOREIGNTABLEREL,
                                ObjectIdGetDatum(rel->rd_id));
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("foreign table \"%s\" does not exist",
                        RelationGetRelationName(rel))));
    tableform = (Form_pg_foreign_table) GETSTRUCT(tuple);
    server = GetForeignServer(tableform->ftserver);
    fdw = GetForeignDataWrapper(server->fdwid);
 
    memset(repl_val, 0, sizeof(repl_val));
    memset(repl_null, false, sizeof(repl_null));
    memset(repl_repl, false, sizeof(repl_repl));
 
    /* Extract the current options */
    datum = SysCacheGetAttr(FOREIGNTABLEREL,
                            tuple,
                            Anum_pg_foreign_table_ftoptions,
                            &isnull);
    if (isnull)
        datum = PointerGetDatum(NULL);
 
    /* Transform the options */
    datum = transformGenericOptions(ForeignTableRelationId,
                                    datum,
                                    options,
                                    fdw->fdwvalidator);
 
    if (PointerIsValid(DatumGetPointer(datum)))
        repl_val[Anum_pg_foreign_table_ftoptions - 1] = datum;
    else
        repl_null[Anum_pg_foreign_table_ftoptions - 1] = true;
 
    repl_repl[Anum_pg_foreign_table_ftoptions - 1] = true;
 
    /* Everything looks good - update the tuple */
 
    tuple = heap_modify_tuple(tuple, RelationGetDescr(ftrel),
                              repl_val, repl_null, repl_repl);
 
    CatalogTupleUpdate(ftrel, &tuple->t_self, tuple);
 
    /*
     * Invalidate relcache so that all sessions will refresh any cached plans
     * that might depend on the old options.
     */
    CacheInvalidateRelcache(rel);
 
    InvokeObjectPostAlterHook(ForeignTableRelationId,
                              RelationGetRelid(rel), 0);
 
    table_close(ftrel, RowExclusiveLock);
 
    heap_freetuple(tuple);
}
 
/*
 * ALTER TABLE ALTER COLUMN SET COMPRESSION
 *
 * Return value is the address of the modified column
 */
static ObjectAddress
ATExecSetCompression(Relation rel,
                     const char *column,
                     Node *newValue,
                     LOCKMODE lockmode)
{
    Relation    attrel;
    HeapTuple   tuple;
    Form_pg_attribute atttableform;
    AttrNumber  attnum;
    char       *compression;
    char        cmethod;
    ObjectAddress address;
 
    compression = strVal(newValue);
 
    attrel = table_open(AttributeRelationId, RowExclusiveLock);
 
    /* copy the cache entry so we can scribble on it below */
    tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), column);
    if (!HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        column, RelationGetRelationName(rel))));
 
    /* prevent them from altering a system attribute */
    atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
    attnum = atttableform->attnum;
    if (attnum <= 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot alter system column \"%s\"", column)));
 
    /*
     * Check that column type is compressible, then get the attribute
     * compression method code
     */
    cmethod = GetAttributeCompression(atttableform->atttypid, compression);
 
    /* update pg_attribute entry */
    atttableform->attcompression = cmethod;
    CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
 
    InvokeObjectPostAlterHook(RelationRelationId,
                              RelationGetRelid(rel),
                              attnum);
 
    /*
     * Apply the change to indexes as well (only for simple index columns,
     * matching behavior of index.c ConstructTupleDescriptor()).
     */
    SetIndexStorageProperties(rel, attrel, attnum,
                              false, 0,
                              true, cmethod,
                              lockmode);
 
    heap_freetuple(tuple);
 
    table_close(attrel, RowExclusiveLock);
 
    /* make changes visible */
    CommandCounterIncrement();
 
    ObjectAddressSubSet(address, RelationRelationId,
                        RelationGetRelid(rel), attnum);
    return address;
}
 
 
/*
 * Preparation phase for SET LOGGED/UNLOGGED
 *
 * This verifies that we're not trying to change a temp table.  Also,
 * existing foreign key constraints are checked to avoid ending up with
 * permanent tables referencing unlogged tables.
 */
static void
ATPrepChangePersistence(AlteredTableInfo *tab, Relation rel, bool toLogged)
{
    Relation    pg_constraint;
    HeapTuple   tuple;
    SysScanDesc scan;
    ScanKeyData skey[1];
 
    /*
     * Disallow changing status for a temp table.  Also verify whether we can
     * get away with doing nothing; in such cases we don't need to run the
     * checks below, either.
     */
    switch (rel->rd_rel->relpersistence)
    {
        case RELPERSISTENCE_TEMP:
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("cannot change logged status of table \"%s\" because it is temporary",
                            RelationGetRelationName(rel)),
                     errtable(rel)));
            break;
        case RELPERSISTENCE_PERMANENT:
            if (toLogged)
                /* nothing to do */
                return;
            break;
        case RELPERSISTENCE_UNLOGGED:
            if (!toLogged)
                /* nothing to do */
                return;
            break;
    }
 
    /*
     * Check that the table is not part of any publication when changing to
     * UNLOGGED, as UNLOGGED tables can't be published.
     */
    if (!toLogged &&
        GetRelationPublications(RelationGetRelid(rel)) != NIL)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cannot change table \"%s\" to unlogged because it is part of a publication",
                        RelationGetRelationName(rel)),
                 errdetail("Unlogged relations cannot be replicated.")));
 
    /*
     * Check existing foreign key constraints to preserve the invariant that
     * permanent tables cannot reference unlogged ones.  Self-referencing
     * foreign keys can safely be ignored.
     */
    pg_constraint = table_open(ConstraintRelationId, AccessShareLock);
 
    /*
     * Scan conrelid if changing to permanent, else confrelid.  This also
     * determines whether a useful index exists.
     */
    ScanKeyInit(&skey[0],
                toLogged ? Anum_pg_constraint_conrelid :
                Anum_pg_constraint_confrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(rel)));
    scan = systable_beginscan(pg_constraint,
                              toLogged ? ConstraintRelidTypidNameIndexId : InvalidOid,
                              true, NULL, 1, skey);
 
    while (HeapTupleIsValid(tuple = systable_getnext(scan)))
    {
        Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
 
        if (con->contype == CONSTRAINT_FOREIGN)
        {
            Oid         foreignrelid;
            Relation    foreignrel;
 
            /* the opposite end of what we used as scankey */
            foreignrelid = toLogged ? con->confrelid : con->conrelid;
 
            /* ignore if self-referencing */
            if (RelationGetRelid(rel) == foreignrelid)
                continue;
 
            foreignrel = relation_open(foreignrelid, AccessShareLock);
 
            if (toLogged)
            {
                if (!RelationIsPermanent(foreignrel))
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                             errmsg("could not change table \"%s\" to logged because it references unlogged table \"%s\"",
                                    RelationGetRelationName(rel),
                                    RelationGetRelationName(foreignrel)),
                             errtableconstraint(rel, NameStr(con->conname))));
            }
            else
            {
                if (RelationIsPermanent(foreignrel))
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                             errmsg("could not change table \"%s\" to unlogged because it references logged table \"%s\"",
                                    RelationGetRelationName(rel),
                                    RelationGetRelationName(foreignrel)),
                             errtableconstraint(rel, NameStr(con->conname))));
            }
 
            relation_close(foreignrel, AccessShareLock);
        }
    }
 
    systable_endscan(scan);
 
    table_close(pg_constraint, AccessShareLock);
 
    /* force rewrite if necessary; see comment in ATRewriteTables */
    tab->rewrite |= AT_REWRITE_ALTER_PERSISTENCE;
    if (toLogged)
        tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
    else
        tab->newrelpersistence = RELPERSISTENCE_UNLOGGED;
    tab->chgPersistence = true;
}
 
/*
 * Execute ALTER TABLE SET SCHEMA
 */
ObjectAddress
AlterTableNamespace(AlterObjectSchemaStmt *stmt, Oid *oldschema)
{
    Relation    rel;
    Oid         relid;
    Oid         oldNspOid;
    Oid         nspOid;
    RangeVar   *newrv;
    ObjectAddresses *objsMoved;
    ObjectAddress myself;
 
    relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
                                     stmt->missing_ok ? RVR_MISSING_OK : 0,
                                     RangeVarCallbackForAlterRelation,
                                     (void *) stmt);
 
    if (!OidIsValid(relid))
    {
        ereport(NOTICE,
                (errmsg("relation \"%s\" does not exist, skipping",
                        stmt->relation->relname)));
        return InvalidObjectAddress;
    }
 
    rel = relation_open(relid, NoLock);
 
    oldNspOid = RelationGetNamespace(rel);
 
    /* If it's an owned sequence, disallow moving it by itself. */
    if (rel->rd_rel->relkind == RELKIND_SEQUENCE)
    {
        Oid         tableId;
        int32       colId;
 
        if (sequenceIsOwned(relid, DEPENDENCY_AUTO, &tableId, &colId) ||
            sequenceIsOwned(relid, DEPENDENCY_INTERNAL, &tableId, &colId))
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot move an owned sequence into another schema"),
                     errdetail("Sequence \"%s\" is linked to table \"%s\".",
                               RelationGetRelationName(rel),
                               get_rel_name(tableId))));
    }
 
    /* Get and lock schema OID and check its permissions. */
    newrv = makeRangeVar(stmt->newschema, RelationGetRelationName(rel), -1);
    nspOid = RangeVarGetAndCheckCreationNamespace(newrv, NoLock, NULL);
 
    /* common checks on switching namespaces */
    CheckSetNamespace(oldNspOid, nspOid);
 
    objsMoved = new_object_addresses();
    AlterTableNamespaceInternal(rel, oldNspOid, nspOid, objsMoved);
    free_object_addresses(objsMoved);
 
    ObjectAddressSet(myself, RelationRelationId, relid);
 
    if (oldschema)
        *oldschema = oldNspOid;
 
    /* close rel, but keep lock until commit */
    relation_close(rel, NoLock);
 
    return myself;
}
 
/*
 * The guts of relocating a table or materialized view to another namespace:
 * besides moving the relation itself, its dependent objects are relocated to
 * the new schema.
 */
void
AlterTableNamespaceInternal(Relation rel, Oid oldNspOid, Oid nspOid,
                            ObjectAddresses *objsMoved)
{
    Relation    classRel;
 
    Assert(objsMoved != NULL);
 
    /* OK, modify the pg_class row and pg_depend entry */
    classRel = table_open(RelationRelationId, RowExclusiveLock);
 
    AlterRelationNamespaceInternal(classRel, RelationGetRelid(rel), oldNspOid,
                                   nspOid, true, objsMoved);
 
    /* Fix the table's row type too, if it has one */
    if (OidIsValid(rel->rd_rel->reltype))
        AlterTypeNamespaceInternal(rel->rd_rel->reltype, nspOid,
                                   false,   /* isImplicitArray */
                                   false,   /* ignoreDependent */
                                   false,   /* errorOnTableType */
                                   objsMoved);
 
    /* Fix other dependent stuff */
    AlterIndexNamespaces(classRel, rel, oldNspOid, nspOid, objsMoved);
    AlterSeqNamespaces(classRel, rel, oldNspOid, nspOid,
                       objsMoved, AccessExclusiveLock);
    AlterConstraintNamespaces(RelationGetRelid(rel), oldNspOid, nspOid,
                              false, objsMoved);
 
    table_close(classRel, RowExclusiveLock);
}
 
/*
 * The guts of relocating a relation to another namespace: fix the pg_class
 * entry, and the pg_depend entry if any.  Caller must already have
 * opened and write-locked pg_class.
 */
void
AlterRelationNamespaceInternal(Relation classRel, Oid relOid,
                               Oid oldNspOid, Oid newNspOid,
                               bool hasDependEntry,
                               ObjectAddresses *objsMoved)
{
    HeapTuple   classTup;
    Form_pg_class classForm;
    ObjectAddress thisobj;
    bool        already_done = false;
 
    /* no rel lock for relkind=c so use LOCKTAG_TUPLE */
    classTup = SearchSysCacheLockedCopy1(RELOID, ObjectIdGetDatum(relOid));
    if (!HeapTupleIsValid(classTup))
        elog(ERROR, "cache lookup failed for relation %u", relOid);
    classForm = (Form_pg_class) GETSTRUCT(classTup);
 
    Assert(classForm->relnamespace == oldNspOid);
 
    thisobj.classId = RelationRelationId;
    thisobj.objectId = relOid;
    thisobj.objectSubId = 0;
 
    /*
     * If the object has already been moved, don't move it again.  If it's
     * already in the right place, don't move it, but still fire the object
     * access hook.
     */
    already_done = object_address_present(&thisobj, objsMoved);
    if (!already_done && oldNspOid != newNspOid)
    {
        ItemPointerData otid = classTup->t_self;
 
        /* check for duplicate name (more friendly than unique-index failure) */
        if (get_relname_relid(NameStr(classForm->relname),
                              newNspOid) != InvalidOid)
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_TABLE),
                     errmsg("relation \"%s\" already exists in schema \"%s\"",
                            NameStr(classForm->relname),
                            get_namespace_name(newNspOid))));
 
        /* classTup is a copy, so OK to scribble on */
        classForm->relnamespace = newNspOid;
 
        CatalogTupleUpdate(classRel, &otid, classTup);
        UnlockTuple(classRel, &otid, InplaceUpdateTupleLock);
 
 
        /* Update dependency on schema if caller said so */
        if (hasDependEntry &&
            changeDependencyFor(RelationRelationId,
                                relOid,
                                NamespaceRelationId,
                                oldNspOid,
                                newNspOid) != 1)
            elog(ERROR, "could not change schema dependency for relation \"%s\"",
                 NameStr(classForm->relname));
    }
    else
        UnlockTuple(classRel, &classTup->t_self, InplaceUpdateTupleLock);
    if (!already_done)
    {
        add_exact_object_address(&thisobj, objsMoved);
 
        InvokeObjectPostAlterHook(RelationRelationId, relOid, 0);
    }
 
    heap_freetuple(classTup);
}
 
/*
 * Move all indexes for the specified relation to another namespace.
 *
 * Note: we assume adequate permission checking was done by the caller,
 * and that the caller has a suitable lock on the owning relation.
 */
static void
AlterIndexNamespaces(Relation classRel, Relation rel,
                     Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved)
{
    List       *indexList;
    ListCell   *l;
 
    indexList = RelationGetIndexList(rel);
 
    foreach(l, indexList)
    {
        Oid         indexOid = lfirst_oid(l);
        ObjectAddress thisobj;
 
        thisobj.classId = RelationRelationId;
        thisobj.objectId = indexOid;
        thisobj.objectSubId = 0;
 
        /*
         * Note: currently, the index will not have its own dependency on the
         * namespace, so we don't need to do changeDependencyFor(). There's no
         * row type in pg_type, either.
         *
         * XXX this objsMoved test may be pointless -- surely we have a single
         * dependency link from a relation to each index?
         */
        if (!object_address_present(&thisobj, objsMoved))
        {
            AlterRelationNamespaceInternal(classRel, indexOid,
                                           oldNspOid, newNspOid,
                                           false, objsMoved);
            add_exact_object_address(&thisobj, objsMoved);
        }
    }
 
    list_free(indexList);
}
 
/*
 * Move all identity and SERIAL-column sequences of the specified relation to another
 * namespace.
 *
 * Note: we assume adequate permission checking was done by the caller,
 * and that the caller has a suitable lock on the owning relation.
 */
static void
AlterSeqNamespaces(Relation classRel, Relation rel,
                   Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved,
                   LOCKMODE lockmode)
{
    Relation    depRel;
    SysScanDesc scan;
    ScanKeyData key[2];
    HeapTuple   tup;
 
    /*
     * SERIAL sequences are those having an auto dependency on one of the
     * table's columns (we don't care *which* column, exactly).
     */
    depRel = table_open(DependRelationId, AccessShareLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_depend_refclassid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationRelationId));
    ScanKeyInit(&key[1],
                Anum_pg_depend_refobjid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(rel)));
    /* we leave refobjsubid unspecified */
 
    scan = systable_beginscan(depRel, DependReferenceIndexId, true,
                              NULL, 2, key);
 
    while (HeapTupleIsValid(tup = systable_getnext(scan)))
    {
        Form_pg_depend depForm = (Form_pg_depend) GETSTRUCT(tup);
        Relation    seqRel;
 
        /* skip dependencies other than auto dependencies on columns */
        if (depForm->refobjsubid == 0 ||
            depForm->classid != RelationRelationId ||
            depForm->objsubid != 0 ||
            !(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
            continue;
 
        /* Use relation_open just in case it's an index */
        seqRel = relation_open(depForm->objid, lockmode);
 
        /* skip non-sequence relations */
        if (RelationGetForm(seqRel)->relkind != RELKIND_SEQUENCE)
        {
            /* No need to keep the lock */
            relation_close(seqRel, lockmode);
            continue;
        }
 
        /* Fix the pg_class and pg_depend entries */
        AlterRelationNamespaceInternal(classRel, depForm->objid,
                                       oldNspOid, newNspOid,
                                       true, objsMoved);
 
        /*
         * Sequences used to have entries in pg_type, but no longer do.  If we
         * ever re-instate that, we'll need to move the pg_type entry to the
         * new namespace, too (using AlterTypeNamespaceInternal).
         */
        Assert(RelationGetForm(seqRel)->reltype == InvalidOid);
 
        /* Now we can close it.  Keep the lock till end of transaction. */
        relation_close(seqRel, NoLock);
    }
 
    systable_endscan(scan);
 
    relation_close(depRel, AccessShareLock);
}
 
 
/*
 * This code supports
 *  CREATE TEMP TABLE ... ON COMMIT { DROP | PRESERVE ROWS | DELETE ROWS }
 *
 * Because we only support this for TEMP tables, it's sufficient to remember
 * the state in a backend-local data structure.
 */
 
/*
 * Register a newly-created relation's ON COMMIT action.
 */
void
register_on_commit_action(Oid relid, OnCommitAction action)
{
    OnCommitItem *oc;
    MemoryContext oldcxt;
 
    /*
     * We needn't bother registering the relation unless there is an ON COMMIT
     * action we need to take.
     */
    if (action == ONCOMMIT_NOOP || action == ONCOMMIT_PRESERVE_ROWS)
        return;
 
    oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
 
    oc = (OnCommitItem *) palloc(sizeof(OnCommitItem));
    oc->relid = relid;
    oc->oncommit = action;
    oc->creating_subid = GetCurrentSubTransactionId();
    oc->deleting_subid = InvalidSubTransactionId;
 
    /*
     * We use lcons() here so that ON COMMIT actions are processed in reverse
     * order of registration.  That might not be essential but it seems
     * reasonable.
     */
    on_commits = lcons(oc, on_commits);
 
    MemoryContextSwitchTo(oldcxt);
}
 
/*
 * Unregister any ON COMMIT action when a relation is deleted.
 *
 * Actually, we only mark the OnCommitItem entry as to be deleted after commit.
 */
void
remove_on_commit_action(Oid relid)
{
    ListCell   *l;
 
    foreach(l, on_commits)
    {
        OnCommitItem *oc = (OnCommitItem *) lfirst(l);
 
        if (oc->relid == relid)
        {
            oc->deleting_subid = GetCurrentSubTransactionId();
            break;
        }
    }
}
 
/*
 * Perform ON COMMIT actions.
 *
 * This is invoked just before actually committing, since it's possible
 * to encounter errors.
 */
void
PreCommit_on_commit_actions(void)
{
    ListCell   *l;
    List       *oids_to_truncate = NIL;
    List       *oids_to_drop = NIL;
 
    foreach(l, on_commits)
    {
        OnCommitItem *oc = (OnCommitItem *) lfirst(l);
 
        /* Ignore entry if already dropped in this xact */
        if (oc->deleting_subid != InvalidSubTransactionId)
            continue;
 
        switch (oc->oncommit)
        {
            case ONCOMMIT_NOOP:
            case ONCOMMIT_PRESERVE_ROWS:
                /* Do nothing (there shouldn't be such entries, actually) */
                break;
            case ONCOMMIT_DELETE_ROWS:
 
                /*
                 * If this transaction hasn't accessed any temporary
                 * relations, we can skip truncating ON COMMIT DELETE ROWS
                 * tables, as they must still be empty.
                 */
                if ((MyXactFlags & XACT_FLAGS_ACCESSEDTEMPNAMESPACE))
                    oids_to_truncate = lappend_oid(oids_to_truncate, oc->relid);
                break;
            case ONCOMMIT_DROP:
                oids_to_drop = lappend_oid(oids_to_drop, oc->relid);
                break;
        }
    }
 
    /*
     * Truncate relations before dropping so that all dependencies between
     * relations are removed after they are worked on.  Doing it like this
     * might be a waste as it is possible that a relation being truncated will
     * be dropped anyway due to its parent being dropped, but this makes the
     * code more robust because of not having to re-check that the relation
     * exists at truncation time.
     */
    if (oids_to_truncate != NIL)
        heap_truncate(oids_to_truncate);
 
    if (oids_to_drop != NIL)
    {
        ObjectAddresses *targetObjects = new_object_addresses();
 
        foreach(l, oids_to_drop)
        {
            ObjectAddress object;
 
            object.classId = RelationRelationId;
            object.objectId = lfirst_oid(l);
            object.objectSubId = 0;
 
            Assert(!object_address_present(&object, targetObjects));
 
            add_exact_object_address(&object, targetObjects);
        }
 
        /*
         * Object deletion might involve toast table access (to clean up
         * toasted catalog entries), so ensure we have a valid snapshot.
         */
        PushActiveSnapshot(GetTransactionSnapshot());
 
        /*
         * Since this is an automatic drop, rather than one directly initiated
         * by the user, we pass the PERFORM_DELETION_INTERNAL flag.
         */
        performMultipleDeletions(targetObjects, DROP_CASCADE,
                                 PERFORM_DELETION_INTERNAL | PERFORM_DELETION_QUIETLY);
 
        PopActiveSnapshot();
 
#ifdef USE_ASSERT_CHECKING
 
        /*
         * Note that table deletion will call remove_on_commit_action, so the
         * entry should get marked as deleted.
         */
        foreach(l, on_commits)
        {
            OnCommitItem *oc = (OnCommitItem *) lfirst(l);
 
            if (oc->oncommit != ONCOMMIT_DROP)
                continue;
 
            Assert(oc->deleting_subid != InvalidSubTransactionId);
        }
#endif
    }
}
 
/*
 * Post-commit or post-abort cleanup for ON COMMIT management.
 *
 * All we do here is remove no-longer-needed OnCommitItem entries.
 *
 * During commit, remove entries that were deleted during this transaction;
 * during abort, remove those created during this transaction.
 */
void
AtEOXact_on_commit_actions(bool isCommit)
{
    ListCell   *cur_item;
 
    foreach(cur_item, on_commits)
    {
        OnCommitItem *oc = (OnCommitItem *) lfirst(cur_item);
 
        if (isCommit ? oc->deleting_subid != InvalidSubTransactionId :
            oc->creating_subid != InvalidSubTransactionId)
        {
            /* cur_item must be removed */
            on_commits = foreach_delete_current(on_commits, cur_item);
            pfree(oc);
        }
        else
        {
            /* cur_item must be preserved */
            oc->creating_subid = InvalidSubTransactionId;
            oc->deleting_subid = InvalidSubTransactionId;
        }
    }
}
 
/*
 * Post-subcommit or post-subabort cleanup for ON COMMIT management.
 *
 * During subabort, we can immediately remove entries created during this
 * subtransaction.  During subcommit, just relabel entries marked during
 * this subtransaction as being the parent's responsibility.
 */
void
AtEOSubXact_on_commit_actions(bool isCommit, SubTransactionId mySubid,
                              SubTransactionId parentSubid)
{
    ListCell   *cur_item;
 
    foreach(cur_item, on_commits)
    {
        OnCommitItem *oc = (OnCommitItem *) lfirst(cur_item);
 
        if (!isCommit && oc->creating_subid == mySubid)
        {
            /* cur_item must be removed */
            on_commits = foreach_delete_current(on_commits, cur_item);
            pfree(oc);
        }
        else
        {
            /* cur_item must be preserved */
            if (oc->creating_subid == mySubid)
                oc->creating_subid = parentSubid;
            if (oc->deleting_subid == mySubid)
                oc->deleting_subid = isCommit ? parentSubid : InvalidSubTransactionId;
        }
    }
}
 
/*
 * This is intended as a callback for RangeVarGetRelidExtended().  It allows
 * the relation to be locked only if (1) it's a plain or partitioned table,
 * materialized view, or TOAST table and (2) the current user is the owner (or
 * the superuser) or has been granted MAINTAIN.  This meets the
 * permission-checking needs of CLUSTER, REINDEX TABLE, and REFRESH
 * MATERIALIZED VIEW; we expose it here so that it can be used by all.
 */
void
RangeVarCallbackMaintainsTable(const RangeVar *relation,
                               Oid relId, Oid oldRelId, void *arg)
{
    char        relkind;
    AclResult   aclresult;
 
    /* Nothing to do if the relation was not found. */
    if (!OidIsValid(relId))
        return;
 
    /*
     * If the relation does exist, check whether it's an index.  But note that
     * the relation might have been dropped between the time we did the name
     * lookup and now.  In that case, there's nothing to do.
     */
    relkind = get_rel_relkind(relId);
    if (!relkind)
        return;
    if (relkind != RELKIND_RELATION && relkind != RELKIND_TOASTVALUE &&
        relkind != RELKIND_MATVIEW && relkind != RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a table or materialized view", relation->relname)));
 
    /* Check permissions */
    aclresult = pg_class_aclcheck(relId, GetUserId(), ACL_MAINTAIN);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult,
                       get_relkind_objtype(get_rel_relkind(relId)),
                       relation->relname);
}
 
/*
 * Callback to RangeVarGetRelidExtended() for TRUNCATE processing.
 */
static void
RangeVarCallbackForTruncate(const RangeVar *relation,
                            Oid relId, Oid oldRelId, void *arg)
{
    HeapTuple   tuple;
 
    /* Nothing to do if the relation was not found. */
    if (!OidIsValid(relId))
        return;
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relId));
    if (!HeapTupleIsValid(tuple))   /* should not happen */
        elog(ERROR, "cache lookup failed for relation %u", relId);
 
    truncate_check_rel(relId, (Form_pg_class) GETSTRUCT(tuple));
    truncate_check_perms(relId, (Form_pg_class) GETSTRUCT(tuple));
 
    ReleaseSysCache(tuple);
}
 
/*
 * Callback for RangeVarGetRelidExtended().  Checks that the current user is
 * the owner of the relation, or superuser.
 */
void
RangeVarCallbackOwnsRelation(const RangeVar *relation,
                             Oid relId, Oid oldRelId, void *arg)
{
    HeapTuple   tuple;
 
    /* Nothing to do if the relation was not found. */
    if (!OidIsValid(relId))
        return;
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relId));
    if (!HeapTupleIsValid(tuple))   /* should not happen */
        elog(ERROR, "cache lookup failed for relation %u", relId);
 
    if (!object_ownercheck(RelationRelationId, relId, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relId)),
                       relation->relname);
 
    if (!allowSystemTableMods &&
        IsSystemClass(relId, (Form_pg_class) GETSTRUCT(tuple)))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: \"%s\" is a system catalog",
                        relation->relname)));
 
    ReleaseSysCache(tuple);
}
 
/*
 * Common RangeVarGetRelid callback for rename, set schema, and alter table
 * processing.
 */
static void
RangeVarCallbackForAlterRelation(const RangeVar *rv, Oid relid, Oid oldrelid,
                                 void *arg)
{
    Node       *stmt = (Node *) arg;
    ObjectType  reltype;
    HeapTuple   tuple;
    Form_pg_class classform;
    AclResult   aclresult;
    char        relkind;
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tuple))
        return;                 /* concurrently dropped */
    classform = (Form_pg_class) GETSTRUCT(tuple);
    relkind = classform->relkind;
 
    /* Must own relation. */
    if (!object_ownercheck(RelationRelationId, relid, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);
 
    /* No system table modifications unless explicitly allowed. */
    if (!allowSystemTableMods && IsSystemClass(relid, classform))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: \"%s\" is a system catalog",
                        rv->relname)));
 
    /*
     * Extract the specified relation type from the statement parse tree.
     *
     * Also, for ALTER .. RENAME, check permissions: the user must (still)
     * have CREATE rights on the containing namespace.
     */
    if (IsA(stmt, RenameStmt))
    {
        aclresult = object_aclcheck(NamespaceRelationId, classform->relnamespace,
                                    GetUserId(), ACL_CREATE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, OBJECT_SCHEMA,
                           get_namespace_name(classform->relnamespace));
        reltype = ((RenameStmt *) stmt)->renameType;
    }
    else if (IsA(stmt, AlterObjectSchemaStmt))
        reltype = ((AlterObjectSchemaStmt *) stmt)->objectType;
 
    else if (IsA(stmt, AlterTableStmt))
        reltype = ((AlterTableStmt *) stmt)->objtype;
    else
    {
        elog(ERROR, "unrecognized node type: %d", (int) nodeTag(stmt));
        reltype = OBJECT_TABLE; /* placate compiler */
    }
 
    /*
     * For compatibility with prior releases, we allow ALTER TABLE to be used
     * with most other types of relations (but not composite types). We allow
     * similar flexibility for ALTER INDEX in the case of RENAME, but not
     * otherwise.  Otherwise, the user must select the correct form of the
     * command for the relation at issue.
     */
    if (reltype == OBJECT_SEQUENCE && relkind != RELKIND_SEQUENCE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a sequence", rv->relname)));
 
    if (reltype == OBJECT_VIEW && relkind != RELKIND_VIEW)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a view", rv->relname)));
 
    if (reltype == OBJECT_MATVIEW && relkind != RELKIND_MATVIEW)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a materialized view", rv->relname)));
 
    if (reltype == OBJECT_FOREIGN_TABLE && relkind != RELKIND_FOREIGN_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a foreign table", rv->relname)));
 
    if (reltype == OBJECT_TYPE && relkind != RELKIND_COMPOSITE_TYPE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a composite type", rv->relname)));
 
    if (reltype == OBJECT_INDEX && relkind != RELKIND_INDEX &&
        relkind != RELKIND_PARTITIONED_INDEX
        && !IsA(stmt, RenameStmt))
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not an index", rv->relname)));
 
    /*
     * Don't allow ALTER TABLE on composite types. We want people to use ALTER
     * TYPE for that.
     */
    if (reltype != OBJECT_TYPE && relkind == RELKIND_COMPOSITE_TYPE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is a composite type", rv->relname),
        /* translator: %s is an SQL ALTER command */
                 errhint("Use %s instead.",
                         "ALTER TYPE")));
 
    /*
     * Don't allow ALTER TABLE .. SET SCHEMA on relations that can't be moved
     * to a different schema, such as indexes and TOAST tables.
     */
    if (IsA(stmt, AlterObjectSchemaStmt))
    {
        if (relkind == RELKIND_INDEX || relkind == RELKIND_PARTITIONED_INDEX)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot change schema of index \"%s\"",
                            rv->relname),
                     errhint("Change the schema of the table instead.")));
        else if (relkind == RELKIND_COMPOSITE_TYPE)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot change schema of composite type \"%s\"",
                            rv->relname),
            /* translator: %s is an SQL ALTER command */
                     errhint("Use %s instead.",
                             "ALTER TYPE")));
        else if (relkind == RELKIND_TOASTVALUE)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("cannot change schema of TOAST table \"%s\"",
                            rv->relname),
                     errhint("Change the schema of the table instead.")));
    }
 
    ReleaseSysCache(tuple);
}
 
/*
 * Transform any expressions present in the partition key
 *
 * Returns a transformed PartitionSpec.
 */
static PartitionSpec *
transformPartitionSpec(Relation rel, PartitionSpec *partspec)
{
    PartitionSpec *newspec;
    ParseState *pstate;
    ParseNamespaceItem *nsitem;
    ListCell   *l;
 
    newspec = makeNode(PartitionSpec);
 
    newspec->strategy = partspec->strategy;
    newspec->partParams = NIL;
    newspec->location = partspec->location;
 
    /* Check valid number of columns for strategy */
    if (partspec->strategy == PARTITION_STRATEGY_LIST &&
        list_length(partspec->partParams) != 1)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("cannot use \"list\" partition strategy with more than one column")));
 
    /*
     * Create a dummy ParseState and insert the target relation as its sole
     * rangetable entry.  We need a ParseState for transformExpr.
     */
    pstate = make_parsestate(NULL);
    nsitem = addRangeTableEntryForRelation(pstate, rel, AccessShareLock,
                                           NULL, false, true);
    addNSItemToQuery(pstate, nsitem, true, true, true);
 
    /* take care of any partition expressions */
    foreach(l, partspec->partParams)
    {
        PartitionElem *pelem = lfirst_node(PartitionElem, l);
 
        if (pelem->expr)
        {
            /* Copy, to avoid scribbling on the input */
            pelem = copyObject(pelem);
 
            /* Now do parse transformation of the expression */
            pelem->expr = transformExpr(pstate, pelem->expr,
                                        EXPR_KIND_PARTITION_EXPRESSION);
 
            /* we have to fix its collations too */
            assign_expr_collations(pstate, pelem->expr);
        }
 
        newspec->partParams = lappend(newspec->partParams, pelem);
    }
 
    return newspec;
}
 
/*
 * Compute per-partition-column information from a list of PartitionElems.
 * Expressions in the PartitionElems must be parse-analyzed already.
 */
static void
ComputePartitionAttrs(ParseState *pstate, Relation rel, List *partParams, AttrNumber *partattrs,
                      List **partexprs, Oid *partopclass, Oid *partcollation,
                      PartitionStrategy strategy)
{
    int         attn;
    ListCell   *lc;
    Oid         am_oid;
 
    attn = 0;
    foreach(lc, partParams)
    {
        PartitionElem *pelem = lfirst_node(PartitionElem, lc);
        Oid         atttype;
        Oid         attcollation;
 
        if (pelem->name != NULL)
        {
            /* Simple attribute reference */
            HeapTuple   atttuple;
            Form_pg_attribute attform;
 
            atttuple = SearchSysCacheAttName(RelationGetRelid(rel),
                                             pelem->name);
            if (!HeapTupleIsValid(atttuple))
                ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" named in partition key does not exist",
                                pelem->name),
                         parser_errposition(pstate, pelem->location)));
            attform = (Form_pg_attribute) GETSTRUCT(atttuple);
 
            if (attform->attnum <= 0)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("cannot use system column \"%s\" in partition key",
                                pelem->name),
                         parser_errposition(pstate, pelem->location)));
 
            /*
             * Generated columns cannot work: They are computed after BEFORE
             * triggers, but partition routing is done before all triggers.
             */
            if (attform->attgenerated)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("cannot use generated column in partition key"),
                         errdetail("Column \"%s\" is a generated column.",
                                   pelem->name),
                         parser_errposition(pstate, pelem->location)));
 
            partattrs[attn] = attform->attnum;
            atttype = attform->atttypid;
            attcollation = attform->attcollation;
            ReleaseSysCache(atttuple);
        }
        else
        {
            /* Expression */
            Node       *expr = pelem->expr;
            char        partattname[16];
 
            Assert(expr != NULL);
            atttype = exprType(expr);
            attcollation = exprCollation(expr);
 
            /*
             * The expression must be of a storable type (e.g., not RECORD).
             * The test is the same as for whether a table column is of a safe
             * type (which is why we needn't check for the non-expression
             * case).
             */
            snprintf(partattname, sizeof(partattname), "%d", attn + 1);
            CheckAttributeType(partattname,
                               atttype, attcollation,
                               NIL, CHKATYPE_IS_PARTKEY);
 
            /*
             * Strip any top-level COLLATE clause.  This ensures that we treat
             * "x COLLATE y" and "(x COLLATE y)" alike.
             */
            while (IsA(expr, CollateExpr))
                expr = (Node *) ((CollateExpr *) expr)->arg;
 
            if (IsA(expr, Var) &&
                ((Var *) expr)->varattno > 0)
            {
                /*
                 * User wrote "(column)" or "(column COLLATE something)".
                 * Treat it like simple attribute anyway.
                 */
                partattrs[attn] = ((Var *) expr)->varattno;
            }
            else
            {
                Bitmapset  *expr_attrs = NULL;
                int         i;
 
                partattrs[attn] = 0;    /* marks the column as expression */
                *partexprs = lappend(*partexprs, expr);
 
                /*
                 * transformPartitionSpec() should have already rejected
                 * subqueries, aggregates, window functions, and SRFs, based
                 * on the EXPR_KIND_ for partition expressions.
                 */
 
                /*
                 * Cannot allow system column references, since that would
                 * make partition routing impossible: their values won't be
                 * known yet when we need to do that.
                 */
                pull_varattnos(expr, 1, &expr_attrs);
                for (i = FirstLowInvalidHeapAttributeNumber; i < 0; i++)
                {
                    if (bms_is_member(i - FirstLowInvalidHeapAttributeNumber,
                                      expr_attrs))
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("partition key expressions cannot contain system column references")));
                }
 
                /*
                 * Generated columns cannot work: They are computed after
                 * BEFORE triggers, but partition routing is done before all
                 * triggers.
                 */
                i = -1;
                while ((i = bms_next_member(expr_attrs, i)) >= 0)
                {
                    AttrNumber  attno = i + FirstLowInvalidHeapAttributeNumber;
 
                    if (attno > 0 &&
                        TupleDescAttr(RelationGetDescr(rel), attno - 1)->attgenerated)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("cannot use generated column in partition key"),
                                 errdetail("Column \"%s\" is a generated column.",
                                           get_attname(RelationGetRelid(rel), attno, false)),
                                 parser_errposition(pstate, pelem->location)));
                }
 
                /*
                 * Preprocess the expression before checking for mutability.
                 * This is essential for the reasons described in
                 * contain_mutable_functions_after_planning.  However, we call
                 * expression_planner for ourselves rather than using that
                 * function, because if constant-folding reduces the
                 * expression to a constant, we'd like to know that so we can
                 * complain below.
                 *
                 * Like contain_mutable_functions_after_planning, assume that
                 * expression_planner won't scribble on its input, so this
                 * won't affect the partexprs entry we saved above.
                 */
                expr = (Node *) expression_planner((Expr *) expr);
 
                /*
                 * Partition expressions cannot contain mutable functions,
                 * because a given row must always map to the same partition
                 * as long as there is no change in the partition boundary
                 * structure.
                 */
                if (contain_mutable_functions(expr))
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                             errmsg("functions in partition key expression must be marked IMMUTABLE")));
 
                /*
                 * While it is not exactly *wrong* for a partition expression
                 * to be a constant, it seems better to reject such keys.
                 */
                if (IsA(expr, Const))
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                             errmsg("cannot use constant expression as partition key")));
            }
        }
 
        /*
         * Apply collation override if any
         */
        if (pelem->collation)
            attcollation = get_collation_oid(pelem->collation, false);
 
        /*
         * Check we have a collation iff it's a collatable type.  The only
         * expected failures here are (1) COLLATE applied to a noncollatable
         * type, or (2) partition expression had an unresolved collation. But
         * we might as well code this to be a complete consistency check.
         */
        if (type_is_collatable(atttype))
        {
            if (!OidIsValid(attcollation))
                ereport(ERROR,
                        (errcode(ERRCODE_INDETERMINATE_COLLATION),
                         errmsg("could not determine which collation to use for partition expression"),
                         errhint("Use the COLLATE clause to set the collation explicitly.")));
        }
        else
        {
            if (OidIsValid(attcollation))
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("collations are not supported by type %s",
                                format_type_be(atttype))));
        }
 
        partcollation[attn] = attcollation;
 
        /*
         * Identify the appropriate operator class.  For list and range
         * partitioning, we use a btree operator class; hash partitioning uses
         * a hash operator class.
         */
        if (strategy == PARTITION_STRATEGY_HASH)
            am_oid = HASH_AM_OID;
        else
            am_oid = BTREE_AM_OID;
 
        if (!pelem->opclass)
        {
            partopclass[attn] = GetDefaultOpClass(atttype, am_oid);
 
            if (!OidIsValid(partopclass[attn]))
            {
                if (strategy == PARTITION_STRATEGY_HASH)
                    ereport(ERROR,
                            (errcode(ERRCODE_UNDEFINED_OBJECT),
                             errmsg("data type %s has no default operator class for access method \"%s\"",
                                    format_type_be(atttype), "hash"),
                             errhint("You must specify a hash operator class or define a default hash operator class for the data type.")));
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_UNDEFINED_OBJECT),
                             errmsg("data type %s has no default operator class for access method \"%s\"",
                                    format_type_be(atttype), "btree"),
                             errhint("You must specify a btree operator class or define a default btree operator class for the data type.")));
            }
        }
        else
            partopclass[attn] = ResolveOpClass(pelem->opclass,
                                               atttype,
                                               am_oid == HASH_AM_OID ? "hash" : "btree",
                                               am_oid);
 
        attn++;
    }
}
 
/*
 * PartConstraintImpliedByRelConstraint
 *      Do scanrel's existing constraints imply the partition constraint?
 *
 * "Existing constraints" include its check constraints and column-level
 * not-null constraints.  partConstraint describes the partition constraint,
 * in implicit-AND form.
 */
bool
PartConstraintImpliedByRelConstraint(Relation scanrel,
                                     List *partConstraint)
{
    List       *existConstraint = NIL;
    TupleConstr *constr = RelationGetDescr(scanrel)->constr;
    int         i;
 
    if (constr && constr->has_not_null)
    {
        int         natts = scanrel->rd_att->natts;
 
        for (i = 1; i <= natts; i++)
        {
            Form_pg_attribute att = TupleDescAttr(scanrel->rd_att, i - 1);
 
            if (att->attnotnull && !att->attisdropped)
            {
                NullTest   *ntest = makeNode(NullTest);
 
                ntest->arg = (Expr *) makeVar(1,
                                              i,
                                              att->atttypid,
                                              att->atttypmod,
                                              att->attcollation,
                                              0);
                ntest->nulltesttype = IS_NOT_NULL;
 
                /*
                 * argisrow=false is correct even for a composite column,
                 * because attnotnull does not represent a SQL-spec IS NOT
                 * NULL test in such a case, just IS DISTINCT FROM NULL.
                 */
                ntest->argisrow = false;
                ntest->location = -1;
                existConstraint = lappend(existConstraint, ntest);
            }
        }
    }
 
    return ConstraintImpliedByRelConstraint(scanrel, partConstraint, existConstraint);
}
 
/*
 * ConstraintImpliedByRelConstraint
 *      Do scanrel's existing constraints imply the given constraint?
 *
 * testConstraint is the constraint to validate. provenConstraint is a
 * caller-provided list of conditions which this function may assume
 * to be true. Both provenConstraint and testConstraint must be in
 * implicit-AND form, must only contain immutable clauses, and must
 * contain only Vars with varno = 1.
 */
bool
ConstraintImpliedByRelConstraint(Relation scanrel, List *testConstraint, List *provenConstraint)
{
    List       *existConstraint = list_copy(provenConstraint);
    TupleConstr *constr = RelationGetDescr(scanrel)->constr;
    int         num_check,
                i;
 
    num_check = (constr != NULL) ? constr->num_check : 0;
    for (i = 0; i < num_check; i++)
    {
        Node       *cexpr;
 
        /*
         * If this constraint hasn't been fully validated yet, we must ignore
         * it here.
         */
        if (!constr->check[i].ccvalid)
            continue;
 
        cexpr = stringToNode(constr->check[i].ccbin);
 
        /*
         * Run each expression through const-simplification and
         * canonicalization.  It is necessary, because we will be comparing it
         * to similarly-processed partition constraint expressions, and may
         * fail to detect valid matches without this.
         */
        cexpr = eval_const_expressions(NULL, cexpr);
        cexpr = (Node *) canonicalize_qual((Expr *) cexpr, true);
 
        existConstraint = list_concat(existConstraint,
                                      make_ands_implicit((Expr *) cexpr));
    }
 
    /*
     * Try to make the proof.  Since we are comparing CHECK constraints, we
     * need to use weak implication, i.e., we assume existConstraint is
     * not-false and try to prove the same for testConstraint.
     *
     * Note that predicate_implied_by assumes its first argument is known
     * immutable.  That should always be true for both NOT NULL and partition
     * constraints, so we don't test it here.
     */
    return predicate_implied_by(testConstraint, existConstraint, true);
}
 
/*
 * QueuePartitionConstraintValidation
 *
 * Add an entry to wqueue to have the given partition constraint validated by
 * Phase 3, for the given relation, and all its children.
 *
 * We first verify whether the given constraint is implied by pre-existing
 * relation constraints; if it is, there's no need to scan the table to
 * validate, so don't queue in that case.
 */
static void
QueuePartitionConstraintValidation(List **wqueue, Relation scanrel,
                                   List *partConstraint,
                                   bool validate_default)
{
    /*
     * Based on the table's existing constraints, determine whether or not we
     * may skip scanning the table.
     */
    if (PartConstraintImpliedByRelConstraint(scanrel, partConstraint))
    {
        if (!validate_default)
            ereport(DEBUG1,
                    (errmsg_internal("partition constraint for table \"%s\" is implied by existing constraints",
                                     RelationGetRelationName(scanrel))));
        else
            ereport(DEBUG1,
                    (errmsg_internal("updated partition constraint for default partition \"%s\" is implied by existing constraints",
                                     RelationGetRelationName(scanrel))));
        return;
    }
 
    /*
     * Constraints proved insufficient. For plain relations, queue a
     * validation item now; for partitioned tables, recurse to process each
     * partition.
     */
    if (scanrel->rd_rel->relkind == RELKIND_RELATION)
    {
        AlteredTableInfo *tab;
 
        /* Grab a work queue entry. */
        tab = ATGetQueueEntry(wqueue, scanrel);
        Assert(tab->partition_constraint == NULL);
        tab->partition_constraint = (Expr *) linitial(partConstraint);
        tab->validate_default = validate_default;
    }
    else if (scanrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        PartitionDesc partdesc = RelationGetPartitionDesc(scanrel, true);
        int         i;
 
        for (i = 0; i < partdesc->nparts; i++)
        {
            Relation    part_rel;
            List       *thisPartConstraint;
 
            /*
             * This is the minimum lock we need to prevent deadlocks.
             */
            part_rel = table_open(partdesc->oids[i], AccessExclusiveLock);
 
            /*
             * Adjust the constraint for scanrel so that it matches this
             * partition's attribute numbers.
             */
            thisPartConstraint =
                map_partition_varattnos(partConstraint, 1,
                                        part_rel, scanrel);
 
            QueuePartitionConstraintValidation(wqueue, part_rel,
                                               thisPartConstraint,
                                               validate_default);
            table_close(part_rel, NoLock);  /* keep lock till commit */
        }
    }
}
 
/*
 * ALTER TABLE <name> ATTACH PARTITION <partition-name> FOR VALUES
 *
 * Return the address of the newly attached partition.
 */
static ObjectAddress
ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd,
                      AlterTableUtilityContext *context)
{
    Relation    attachrel,
                catalog;
    List       *attachrel_children;
    List       *partConstraint;
    SysScanDesc scan;
    ScanKeyData skey;
    AttrNumber  attno;
    int         natts;
    TupleDesc   tupleDesc;
    ObjectAddress address;
    const char *trigger_name;
    Oid         defaultPartOid;
    List       *partBoundConstraint;
    ParseState *pstate = make_parsestate(NULL);
 
    pstate->p_sourcetext = context->queryString;
 
    /*
     * We must lock the default partition if one exists, because attaching a
     * new partition will change its partition constraint.
     */
    defaultPartOid =
        get_default_oid_from_partdesc(RelationGetPartitionDesc(rel, true));
    if (OidIsValid(defaultPartOid))
        LockRelationOid(defaultPartOid, AccessExclusiveLock);
 
    attachrel = table_openrv(cmd->name, AccessExclusiveLock);
 
    /*
     * XXX I think it'd be a good idea to grab locks on all tables referenced
     * by FKs at this point also.
     */
 
    /*
     * Must be owner of both parent and source table -- parent was checked by
     * ATSimplePermissions call in ATPrepCmd
     */
    ATSimplePermissions(AT_AttachPartition, attachrel,
                        ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE);
 
    /* A partition can only have one parent */
    if (attachrel->rd_rel->relispartition)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is already a partition",
                        RelationGetRelationName(attachrel))));
 
    if (OidIsValid(attachrel->rd_rel->reloftype))
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot attach a typed table as partition")));
 
    /*
     * Table being attached should not already be part of inheritance; either
     * as a child table...
     */
    catalog = table_open(InheritsRelationId, AccessShareLock);
    ScanKeyInit(&skey,
                Anum_pg_inherits_inhrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(attachrel)));
    scan = systable_beginscan(catalog, InheritsRelidSeqnoIndexId, true,
                              NULL, 1, &skey);
    if (HeapTupleIsValid(systable_getnext(scan)))
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot attach inheritance child as partition")));
    systable_endscan(scan);
 
    /* ...or as a parent table (except the case when it is partitioned) */
    ScanKeyInit(&skey,
                Anum_pg_inherits_inhparent,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(attachrel)));
    scan = systable_beginscan(catalog, InheritsParentIndexId, true, NULL,
                              1, &skey);
    if (HeapTupleIsValid(systable_getnext(scan)) &&
        attachrel->rd_rel->relkind == RELKIND_RELATION)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot attach inheritance parent as partition")));
    systable_endscan(scan);
    table_close(catalog, AccessShareLock);
 
    /*
     * Prevent circularity by seeing if rel is a partition of attachrel. (In
     * particular, this disallows making a rel a partition of itself.)
     *
     * We do that by checking if rel is a member of the list of attachrel's
     * partitions provided the latter is partitioned at all.  We want to avoid
     * having to construct this list again, so we request the strongest lock
     * on all partitions.  We need the strongest lock, because we may decide
     * to scan them if we find out that the table being attached (or its leaf
     * partitions) may contain rows that violate the partition constraint. If
     * the table has a constraint that would prevent such rows, which by
     * definition is present in all the partitions, we need not scan the
     * table, nor its partitions.  But we cannot risk a deadlock by taking a
     * weaker lock now and the stronger one only when needed.
     */
    attachrel_children = find_all_inheritors(RelationGetRelid(attachrel),
                                             AccessExclusiveLock, NULL);
    if (list_member_oid(attachrel_children, RelationGetRelid(rel)))
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_TABLE),
                 errmsg("circular inheritance not allowed"),
                 errdetail("\"%s\" is already a child of \"%s\".",
                           RelationGetRelationName(rel),
                           RelationGetRelationName(attachrel))));
 
    /* If the parent is permanent, so must be all of its partitions. */
    if (rel->rd_rel->relpersistence != RELPERSISTENCE_TEMP &&
        attachrel->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot attach a temporary relation as partition of permanent relation \"%s\"",
                        RelationGetRelationName(rel))));
 
    /* Temp parent cannot have a partition that is itself not a temp */
    if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
        attachrel->rd_rel->relpersistence != RELPERSISTENCE_TEMP)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot attach a permanent relation as partition of temporary relation \"%s\"",
                        RelationGetRelationName(rel))));
 
    /* If the parent is temp, it must belong to this session */
    if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
        !rel->rd_islocaltemp)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot attach as partition of temporary relation of another session")));
 
    /* Ditto for the partition */
    if (attachrel->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
        !attachrel->rd_islocaltemp)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot attach temporary relation of another session as partition")));
 
    /*
     * Check if attachrel has any identity columns or any columns that aren't
     * in the parent.
     */
    tupleDesc = RelationGetDescr(attachrel);
    natts = tupleDesc->natts;
    for (attno = 1; attno <= natts; attno++)
    {
        Form_pg_attribute attribute = TupleDescAttr(tupleDesc, attno - 1);
        char       *attributeName = NameStr(attribute->attname);
 
        /* Ignore dropped */
        if (attribute->attisdropped)
            continue;
 
        if (attribute->attidentity)
            ereport(ERROR,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("table \"%s\" being attached contains an identity column \"%s\"",
                           RelationGetRelationName(attachrel), attributeName),
                    errdetail("The new partition may not contain an identity column."));
 
        /* Try to find the column in parent (matching on column name) */
        if (!SearchSysCacheExists2(ATTNAME,
                                   ObjectIdGetDatum(RelationGetRelid(rel)),
                                   CStringGetDatum(attributeName)))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("table \"%s\" contains column \"%s\" not found in parent \"%s\"",
                            RelationGetRelationName(attachrel), attributeName,
                            RelationGetRelationName(rel)),
                     errdetail("The new partition may contain only the columns present in parent.")));
    }
 
    /*
     * If child_rel has row-level triggers with transition tables, we
     * currently don't allow it to become a partition.  See also prohibitions
     * in ATExecAddInherit() and CreateTrigger().
     */
    trigger_name = FindTriggerIncompatibleWithInheritance(attachrel->trigdesc);
    if (trigger_name != NULL)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("trigger \"%s\" prevents table \"%s\" from becoming a partition",
                        trigger_name, RelationGetRelationName(attachrel)),
                 errdetail("ROW triggers with transition tables are not supported on partitions.")));
 
    /*
     * Check that the new partition's bound is valid and does not overlap any
     * of existing partitions of the parent - note that it does not return on
     * error.
     */
    check_new_partition_bound(RelationGetRelationName(attachrel), rel,
                              cmd->bound, pstate);
 
    /* OK to create inheritance.  Rest of the checks performed there */
    CreateInheritance(attachrel, rel, true);
 
    /* Update the pg_class entry. */
    StorePartitionBound(attachrel, rel, cmd->bound);
 
    /* Ensure there exists a correct set of indexes in the partition. */
    AttachPartitionEnsureIndexes(wqueue, rel, attachrel);
 
    /* and triggers */
    CloneRowTriggersToPartition(rel, attachrel);
 
    /*
     * Clone foreign key constraints.  Callee is responsible for setting up
     * for phase 3 constraint verification.
     */
    CloneForeignKeyConstraints(wqueue, rel, attachrel);
 
    /*
     * Generate partition constraint from the partition bound specification.
     * If the parent itself is a partition, make sure to include its
     * constraint as well.
     */
    partBoundConstraint = get_qual_from_partbound(rel, cmd->bound);
 
    /*
     * Use list_concat_copy() to avoid modifying partBoundConstraint in place,
     * since it's needed later to construct the constraint expression for
     * validating against the default partition, if any.
     */
    partConstraint = list_concat_copy(partBoundConstraint,
                                      RelationGetPartitionQual(rel));
 
    /* Skip validation if there are no constraints to validate. */
    if (partConstraint)
    {
        /*
         * Run the partition quals through const-simplification similar to
         * check constraints.  We skip canonicalize_qual, though, because
         * partition quals should be in canonical form already.
         */
        partConstraint =
            (List *) eval_const_expressions(NULL,
                                            (Node *) partConstraint);
 
        /* XXX this sure looks wrong */
        partConstraint = list_make1(make_ands_explicit(partConstraint));
 
        /*
         * Adjust the generated constraint to match this partition's attribute
         * numbers.
         */
        partConstraint = map_partition_varattnos(partConstraint, 1, attachrel,
                                                 rel);
 
        /* Validate partition constraints against the table being attached. */
        QueuePartitionConstraintValidation(wqueue, attachrel, partConstraint,
                                           false);
    }
 
    /*
     * If we're attaching a partition other than the default partition and a
     * default one exists, then that partition's partition constraint changes,
     * so add an entry to the work queue to validate it, too.  (We must not do
     * this when the partition being attached is the default one; we already
     * did it above!)
     */
    if (OidIsValid(defaultPartOid))
    {
        Relation    defaultrel;
        List       *defPartConstraint;
 
        Assert(!cmd->bound->is_default);
 
        /* we already hold a lock on the default partition */
        defaultrel = table_open(defaultPartOid, NoLock);
        defPartConstraint =
            get_proposed_default_constraint(partBoundConstraint);
 
        /*
         * Map the Vars in the constraint expression from rel's attnos to
         * defaultrel's.
         */
        defPartConstraint =
            map_partition_varattnos(defPartConstraint,
                                    1, defaultrel, rel);
        QueuePartitionConstraintValidation(wqueue, defaultrel,
                                           defPartConstraint, true);
 
        /* keep our lock until commit. */
        table_close(defaultrel, NoLock);
    }
 
    ObjectAddressSet(address, RelationRelationId, RelationGetRelid(attachrel));
 
    /*
     * If the partition we just attached is partitioned itself, invalidate
     * relcache for all descendent partitions too to ensure that their
     * rd_partcheck expression trees are rebuilt; partitions already locked at
     * the beginning of this function.
     */
    if (attachrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        ListCell   *l;
 
        foreach(l, attachrel_children)
        {
            CacheInvalidateRelcacheByRelid(lfirst_oid(l));
        }
    }
 
    /* keep our lock until commit */
    table_close(attachrel, NoLock);
 
    return address;
}
 
/*
 * AttachPartitionEnsureIndexes
 *      subroutine for ATExecAttachPartition to create/match indexes
 *
 * Enforce the indexing rule for partitioned tables during ALTER TABLE / ATTACH
 * PARTITION: every partition must have an index attached to each index on the
 * partitioned table.
 */
static void
AttachPartitionEnsureIndexes(List **wqueue, Relation rel, Relation attachrel)
{
    List       *idxes;
    List       *attachRelIdxs;
    Relation   *attachrelIdxRels;
    IndexInfo **attachInfos;
    ListCell   *cell;
    MemoryContext cxt;
    MemoryContext oldcxt;
 
    cxt = AllocSetContextCreate(CurrentMemoryContext,
                                "AttachPartitionEnsureIndexes",
                                ALLOCSET_DEFAULT_SIZES);
    oldcxt = MemoryContextSwitchTo(cxt);
 
    idxes = RelationGetIndexList(rel);
    attachRelIdxs = RelationGetIndexList(attachrel);
    attachrelIdxRels = palloc(sizeof(Relation) * list_length(attachRelIdxs));
    attachInfos = palloc(sizeof(IndexInfo *) * list_length(attachRelIdxs));
 
    /* Build arrays of all existing indexes and their IndexInfos */
    foreach_oid(cldIdxId, attachRelIdxs)
    {
        int         i = foreach_current_index(cldIdxId);
 
        attachrelIdxRels[i] = index_open(cldIdxId, AccessShareLock);
        attachInfos[i] = BuildIndexInfo(attachrelIdxRels[i]);
    }
 
    /*
     * If we're attaching a foreign table, we must fail if any of the indexes
     * is a constraint index; otherwise, there's nothing to do here.  Do this
     * before starting work, to avoid wasting the effort of building a few
     * non-unique indexes before coming across a unique one.
     */
    if (attachrel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
    {
        foreach(cell, idxes)
        {
            Oid         idx = lfirst_oid(cell);
            Relation    idxRel = index_open(idx, AccessShareLock);
 
            if (idxRel->rd_index->indisunique ||
                idxRel->rd_index->indisprimary)
                ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("cannot attach foreign table \"%s\" as partition of partitioned table \"%s\"",
                                RelationGetRelationName(attachrel),
                                RelationGetRelationName(rel)),
                         errdetail("Partitioned table \"%s\" contains unique indexes.",
                                   RelationGetRelationName(rel))));
            index_close(idxRel, AccessShareLock);
        }
 
        goto out;
    }
 
    /*
     * For each index on the partitioned table, find a matching one in the
     * partition-to-be; if one is not found, create one.
     */
    foreach(cell, idxes)
    {
        Oid         idx = lfirst_oid(cell);
        Relation    idxRel = index_open(idx, AccessShareLock);
        IndexInfo  *info;
        AttrMap    *attmap;
        bool        found = false;
        Oid         constraintOid;
 
        /*
         * Ignore indexes in the partitioned table other than partitioned
         * indexes.
         */
        if (idxRel->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
        {
            index_close(idxRel, AccessShareLock);
            continue;
        }
 
        /* construct an indexinfo to compare existing indexes against */
        info = BuildIndexInfo(idxRel);
        attmap = build_attrmap_by_name(RelationGetDescr(attachrel),
                                       RelationGetDescr(rel),
                                       false);
        constraintOid = get_relation_idx_constraint_oid(RelationGetRelid(rel), idx);
 
        /*
         * Scan the list of existing indexes in the partition-to-be, and mark
         * the first matching, valid, unattached one we find, if any, as
         * partition of the parent index.  If we find one, we're done.
         */
        for (int i = 0; i < list_length(attachRelIdxs); i++)
        {
            Oid         cldIdxId = RelationGetRelid(attachrelIdxRels[i]);
            Oid         cldConstrOid = InvalidOid;
 
            /* does this index have a parent?  if so, can't use it */
            if (attachrelIdxRels[i]->rd_rel->relispartition)
                continue;
 
            /* If this index is invalid, can't use it */
            if (!attachrelIdxRels[i]->rd_index->indisvalid)
                continue;
 
            if (CompareIndexInfo(attachInfos[i], info,
                                 attachrelIdxRels[i]->rd_indcollation,
                                 idxRel->rd_indcollation,
                                 attachrelIdxRels[i]->rd_opfamily,
                                 idxRel->rd_opfamily,
                                 attmap))
            {
                /*
                 * If this index is being created in the parent because of a
                 * constraint, then the child needs to have a constraint also,
                 * so look for one.  If there is no such constraint, this
                 * index is no good, so keep looking.
                 */
                if (OidIsValid(constraintOid))
                {
                    cldConstrOid =
                        get_relation_idx_constraint_oid(RelationGetRelid(attachrel),
                                                        cldIdxId);
                    /* no dice */
                    if (!OidIsValid(cldConstrOid))
                        continue;
 
                    /* Ensure they're both the same type of constraint */
                    if (get_constraint_type(constraintOid) !=
                        get_constraint_type(cldConstrOid))
                        continue;
                }
 
                /* bingo. */
                IndexSetParentIndex(attachrelIdxRels[i], idx);
                if (OidIsValid(constraintOid))
                    ConstraintSetParentConstraint(cldConstrOid, constraintOid,
                                                  RelationGetRelid(attachrel));
                found = true;
 
                CommandCounterIncrement();
                break;
            }
        }
 
        /*
         * If no suitable index was found in the partition-to-be, create one
         * now.
         */
        if (!found)
        {
            IndexStmt  *stmt;
            Oid         conOid;
 
            stmt = generateClonedIndexStmt(NULL,
                                           idxRel, attmap,
                                           &conOid);
            DefineIndex(RelationGetRelid(attachrel), stmt, InvalidOid,
                        RelationGetRelid(idxRel),
                        conOid,
                        -1,
                        true, false, false, false, false);
        }
 
        index_close(idxRel, AccessShareLock);
    }
 
out:
    /* Clean up. */
    for (int i = 0; i < list_length(attachRelIdxs); i++)
        index_close(attachrelIdxRels[i], AccessShareLock);
    MemoryContextSwitchTo(oldcxt);
    MemoryContextDelete(cxt);
}
 
/*
 * CloneRowTriggersToPartition
 *      subroutine for ATExecAttachPartition/DefineRelation to create row
 *      triggers on partitions
 */
static void
CloneRowTriggersToPartition(Relation parent, Relation partition)
{
    Relation    pg_trigger;
    ScanKeyData key;
    SysScanDesc scan;
    HeapTuple   tuple;
    MemoryContext perTupCxt;
 
    ScanKeyInit(&key, Anum_pg_trigger_tgrelid, BTEqualStrategyNumber,
                F_OIDEQ, ObjectIdGetDatum(RelationGetRelid(parent)));
    pg_trigger = table_open(TriggerRelationId, RowExclusiveLock);
    scan = systable_beginscan(pg_trigger, TriggerRelidNameIndexId,
                              true, NULL, 1, &key);
 
    perTupCxt = AllocSetContextCreate(CurrentMemoryContext,
                                      "clone trig", ALLOCSET_SMALL_SIZES);
 
    while (HeapTupleIsValid(tuple = systable_getnext(scan)))
    {
        Form_pg_trigger trigForm = (Form_pg_trigger) GETSTRUCT(tuple);
        CreateTrigStmt *trigStmt;
        Node       *qual = NULL;
        Datum       value;
        bool        isnull;
        List       *cols = NIL;
        List       *trigargs = NIL;
        MemoryContext oldcxt;
 
        /*
         * Ignore statement-level triggers; those are not cloned.
         */
        if (!TRIGGER_FOR_ROW(trigForm->tgtype))
            continue;
 
        /*
         * Don't clone internal triggers, because the constraint cloning code
         * will.
         */
        if (trigForm->tgisinternal)
            continue;
 
        /*
         * Complain if we find an unexpected trigger type.
         */
        if (!TRIGGER_FOR_BEFORE(trigForm->tgtype) &&
            !TRIGGER_FOR_AFTER(trigForm->tgtype))
            elog(ERROR, "unexpected trigger \"%s\" found",
                 NameStr(trigForm->tgname));
 
        /* Use short-lived context for CREATE TRIGGER */
        oldcxt = MemoryContextSwitchTo(perTupCxt);
 
        /*
         * If there is a WHEN clause, generate a 'cooked' version of it that's
         * appropriate for the partition.
         */
        value = heap_getattr(tuple, Anum_pg_trigger_tgqual,
                             RelationGetDescr(pg_trigger), &isnull);
        if (!isnull)
        {
            qual = stringToNode(TextDatumGetCString(value));
            qual = (Node *) map_partition_varattnos((List *) qual, PRS2_OLD_VARNO,
                                                    partition, parent);
            qual = (Node *) map_partition_varattnos((List *) qual, PRS2_NEW_VARNO,
                                                    partition, parent);
        }
 
        /*
         * If there is a column list, transform it to a list of column names.
         * Note we don't need to map this list in any way ...
         */
        if (trigForm->tgattr.dim1 > 0)
        {
            int         i;
 
            for (i = 0; i < trigForm->tgattr.dim1; i++)
            {
                Form_pg_attribute col;
 
                col = TupleDescAttr(parent->rd_att,
                                    trigForm->tgattr.values[i] - 1);
                cols = lappend(cols,
                               makeString(pstrdup(NameStr(col->attname))));
            }
        }
 
        /* Reconstruct trigger arguments list. */
        if (trigForm->tgnargs > 0)
        {
            char       *p;
 
            value = heap_getattr(tuple, Anum_pg_trigger_tgargs,
                                 RelationGetDescr(pg_trigger), &isnull);
            if (isnull)
                elog(ERROR, "tgargs is null for trigger \"%s\" in partition \"%s\"",
                     NameStr(trigForm->tgname), RelationGetRelationName(partition));
 
            p = (char *) VARDATA_ANY(DatumGetByteaPP(value));
 
            for (int i = 0; i < trigForm->tgnargs; i++)
            {
                trigargs = lappend(trigargs, makeString(pstrdup(p)));
                p += strlen(p) + 1;
            }
        }
 
        trigStmt = makeNode(CreateTrigStmt);
        trigStmt->replace = false;
        trigStmt->isconstraint = OidIsValid(trigForm->tgconstraint);
        trigStmt->trigname = NameStr(trigForm->tgname);
        trigStmt->relation = NULL;
        trigStmt->funcname = NULL;  /* passed separately */
        trigStmt->args = trigargs;
        trigStmt->row = true;
        trigStmt->timing = trigForm->tgtype & TRIGGER_TYPE_TIMING_MASK;
        trigStmt->events = trigForm->tgtype & TRIGGER_TYPE_EVENT_MASK;
        trigStmt->columns = cols;
        trigStmt->whenClause = NULL;    /* passed separately */
        trigStmt->transitionRels = NIL; /* not supported at present */
        trigStmt->deferrable = trigForm->tgdeferrable;
        trigStmt->initdeferred = trigForm->tginitdeferred;
        trigStmt->constrrel = NULL; /* passed separately */
 
        CreateTriggerFiringOn(trigStmt, NULL, RelationGetRelid(partition),
                              trigForm->tgconstrrelid, InvalidOid, InvalidOid,
                              trigForm->tgfoid, trigForm->oid, qual,
                              false, true, trigForm->tgenabled);
 
        MemoryContextSwitchTo(oldcxt);
        MemoryContextReset(perTupCxt);
    }
 
    MemoryContextDelete(perTupCxt);
 
    systable_endscan(scan);
    table_close(pg_trigger, RowExclusiveLock);
}
 
/*
 * ALTER TABLE DETACH PARTITION
 *
 * Return the address of the relation that is no longer a partition of rel.
 *
 * If concurrent mode is requested, we run in two transactions.  A side-
 * effect is that this command cannot run in a multi-part ALTER TABLE.
 * Currently, that's enforced by the grammar.
 *
 * The strategy for concurrency is to first modify the partition's
 * pg_inherit catalog row to make it visible to everyone that the
 * partition is detached, lock the partition against writes, and commit
 * the transaction; anyone who requests the partition descriptor from
 * that point onwards has to ignore such a partition.  In a second
 * transaction, we wait until all transactions that could have seen the
 * partition as attached are gone, then we remove the rest of partition
 * metadata (pg_inherits and pg_class.relpartbounds).
 */
static ObjectAddress
ATExecDetachPartition(List **wqueue, AlteredTableInfo *tab, Relation rel,
                      RangeVar *name, bool concurrent)
{
    Relation    partRel;
    ObjectAddress address;
    Oid         defaultPartOid;
 
    /*
     * We must lock the default partition, because detaching this partition
     * will change its partition constraint.
     */
    defaultPartOid =
        get_default_oid_from_partdesc(RelationGetPartitionDesc(rel, true));
    if (OidIsValid(defaultPartOid))
    {
        /*
         * Concurrent detaching when a default partition exists is not
         * supported. The main problem is that the default partition
         * constraint would change.  And there's a definitional problem: what
         * should happen to the tuples that are being inserted that belong to
         * the partition being detached?  Putting them on the partition being
         * detached would be wrong, since they'd become "lost" after the
         * detaching completes but we cannot put them in the default partition
         * either until we alter its partition constraint.
         *
         * I think we could solve this problem if we effected the constraint
         * change before committing the first transaction.  But the lock would
         * have to remain AEL and it would cause concurrent query planning to
         * be blocked, so changing it that way would be even worse.
         */
        if (concurrent)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("cannot detach partitions concurrently when a default partition exists")));
        LockRelationOid(defaultPartOid, AccessExclusiveLock);
    }
 
    /*
     * In concurrent mode, the partition is locked with share-update-exclusive
     * in the first transaction.  This allows concurrent transactions to be
     * doing DML to the partition.
     */
    partRel = table_openrv(name, concurrent ? ShareUpdateExclusiveLock :
                           AccessExclusiveLock);
 
    /*
     * Check inheritance conditions and either delete the pg_inherits row (in
     * non-concurrent mode) or just set the inhdetachpending flag.
     */
    if (!concurrent)
        RemoveInheritance(partRel, rel, false);
    else
        MarkInheritDetached(partRel, rel);
 
    /*
     * Ensure that foreign keys still hold after this detach.  This keeps
     * locks on the referencing tables, which prevents concurrent transactions
     * from adding rows that we wouldn't see.  For this to work in concurrent
     * mode, it is critical that the partition appears as no longer attached
     * for the RI queries as soon as the first transaction commits.
     */
    ATDetachCheckNoForeignKeyRefs(partRel);
 
    /*
     * Concurrent mode has to work harder; first we add a new constraint to
     * the partition that matches the partition constraint.  Then we close our
     * existing transaction, and in a new one wait for all processes to catch
     * up on the catalog updates we've done so far; at that point we can
     * complete the operation.
     */
    if (concurrent)
    {
        Oid         partrelid,
                    parentrelid;
        LOCKTAG     tag;
        char       *parentrelname;
        char       *partrelname;
 
        /*
         * Add a new constraint to the partition being detached, which
         * supplants the partition constraint (unless there is one already).
         */
        DetachAddConstraintIfNeeded(wqueue, partRel);
 
        /*
         * We're almost done now; the only traces that remain are the
         * pg_inherits tuple and the partition's relpartbounds.  Before we can
         * remove those, we need to wait until all transactions that know that
         * this is a partition are gone.
         */
 
        /*
         * Remember relation OIDs to re-acquire them later; and relation names
         * too, for error messages if something is dropped in between.
         */
        partrelid = RelationGetRelid(partRel);
        parentrelid = RelationGetRelid(rel);
        parentrelname = MemoryContextStrdup(PortalContext,
                                            RelationGetRelationName(rel));
        partrelname = MemoryContextStrdup(PortalContext,
                                          RelationGetRelationName(partRel));
 
        /* Invalidate relcache entries for the parent -- must be before close */
        CacheInvalidateRelcache(rel);
 
        table_close(partRel, NoLock);
        table_close(rel, NoLock);
        tab->rel = NULL;
 
        /* Make updated catalog entry visible */
        PopActiveSnapshot();
        CommitTransactionCommand();
 
        StartTransactionCommand();
 
        /*
         * Now wait.  This ensures that all queries that were planned
         * including the partition are finished before we remove the rest of
         * catalog entries.  We don't need or indeed want to acquire this
         * lock, though -- that would block later queries.
         *
         * We don't need to concern ourselves with waiting for a lock on the
         * partition itself, since we will acquire AccessExclusiveLock below.
         */
        SET_LOCKTAG_RELATION(tag, MyDatabaseId, parentrelid);
        WaitForLockersMultiple(list_make1(&tag), AccessExclusiveLock, false);
 
        /*
         * Now acquire locks in both relations again.  Note they may have been
         * removed in the meantime, so care is required.
         */
        rel = try_relation_open(parentrelid, ShareUpdateExclusiveLock);
        partRel = try_relation_open(partrelid, AccessExclusiveLock);
 
        /* If the relations aren't there, something bad happened; bail out */
        if (rel == NULL)
        {
            if (partRel != NULL)    /* shouldn't happen */
                elog(WARNING, "dangling partition \"%s\" remains, can't fix",
                     partrelname);
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("partitioned table \"%s\" was removed concurrently",
                            parentrelname)));
        }
        if (partRel == NULL)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("partition \"%s\" was removed concurrently", partrelname)));
 
        tab->rel = rel;
    }
 
    /* Do the final part of detaching */
    DetachPartitionFinalize(rel, partRel, concurrent, defaultPartOid);
 
    ObjectAddressSet(address, RelationRelationId, RelationGetRelid(partRel));
 
    /* keep our lock until commit */
    table_close(partRel, NoLock);
 
    return address;
}
 
/*
 * Second part of ALTER TABLE .. DETACH.
 *
 * This is separate so that it can be run independently when the second
 * transaction of the concurrent algorithm fails (crash or abort).
 */
static void
DetachPartitionFinalize(Relation rel, Relation partRel, bool concurrent,
                        Oid defaultPartOid)
{
    Relation    classRel;
    List       *fks;
    ListCell   *cell;
    List       *indexes;
    Datum       new_val[Natts_pg_class];
    bool        new_null[Natts_pg_class],
                new_repl[Natts_pg_class];
    HeapTuple   tuple,
                newtuple;
    Relation    trigrel = NULL;
 
    if (concurrent)
    {
        /*
         * We can remove the pg_inherits row now. (In the non-concurrent case,
         * this was already done).
         */
        RemoveInheritance(partRel, rel, true);
    }
 
    /* Drop any triggers that were cloned on creation/attach. */
    DropClonedTriggersFromPartition(RelationGetRelid(partRel));
 
    /*
     * Detach any foreign keys that are inherited.  This includes creating
     * additional action triggers.
     */
    fks = copyObject(RelationGetFKeyList(partRel));
    if (fks != NIL)
        trigrel = table_open(TriggerRelationId, RowExclusiveLock);
    foreach(cell, fks)
    {
        ForeignKeyCacheInfo *fk = lfirst(cell);
        HeapTuple   contup,
                    parentConTup;
        Form_pg_constraint conform;
        Oid         insertTriggerOid,
                    updateTriggerOid;
 
        contup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(fk->conoid));
        if (!HeapTupleIsValid(contup))
            elog(ERROR, "cache lookup failed for constraint %u", fk->conoid);
        conform = (Form_pg_constraint) GETSTRUCT(contup);
 
        /* consider only the inherited foreign keys */
        if (conform->contype != CONSTRAINT_FOREIGN ||
            !OidIsValid(conform->conparentid))
        {
            ReleaseSysCache(contup);
            continue;
        }
 
        Assert(OidIsValid(conform->conparentid));
        parentConTup = SearchSysCache1(CONSTROID,
                                       ObjectIdGetDatum(conform->conparentid));
        if (!HeapTupleIsValid(parentConTup))
            elog(ERROR, "cache lookup failed for constraint %u",
                 conform->conparentid);
 
        /*
         * The constraint on this table must be marked no longer a child of
         * the parent's constraint, as do its check triggers.
         */
        ConstraintSetParentConstraint(fk->conoid, InvalidOid, InvalidOid);
 
        /*
         * Also, look up the partition's "check" triggers corresponding to the
         * constraint being detached and detach them from the parent triggers.
         */
        GetForeignKeyCheckTriggers(trigrel,
                                   fk->conoid, fk->confrelid, fk->conrelid,
                                   &insertTriggerOid, &updateTriggerOid);
        Assert(OidIsValid(insertTriggerOid));
        TriggerSetParentTrigger(trigrel, insertTriggerOid, InvalidOid,
                                RelationGetRelid(partRel));
        Assert(OidIsValid(updateTriggerOid));
        TriggerSetParentTrigger(trigrel, updateTriggerOid, InvalidOid,
                                RelationGetRelid(partRel));
 
        /*
         * Lastly, create the action triggers on the referenced table, using
         * addFkRecurseReferenced, which requires some elaborate setup (so put
         * it in a separate block).  While at it, if the table is partitioned,
         * that function will recurse to create the pg_constraint rows and
         * action triggers for each partition.
         *
         * Note there's no need to do addFkConstraint() here, because the
         * pg_constraint row already exists.
         */
        {
            Constraint *fkconstraint;
            int         numfks;
            AttrNumber  conkey[INDEX_MAX_KEYS];
            AttrNumber  confkey[INDEX_MAX_KEYS];
            Oid         conpfeqop[INDEX_MAX_KEYS];
            Oid         conppeqop[INDEX_MAX_KEYS];
            Oid         conffeqop[INDEX_MAX_KEYS];
            int         numfkdelsetcols;
            AttrNumber  confdelsetcols[INDEX_MAX_KEYS];
            AttrMap    *attmap;
            Relation    refdRel;
 
            DeconstructFkConstraintRow(contup,
                                       &numfks,
                                       conkey,
                                       confkey,
                                       conpfeqop,
                                       conppeqop,
                                       conffeqop,
                                       &numfkdelsetcols,
                                       confdelsetcols);
 
            /* Create a synthetic node we'll use throughout */
            fkconstraint = makeNode(Constraint);
            fkconstraint->contype = CONSTRAINT_FOREIGN;
            fkconstraint->conname = pstrdup(NameStr(conform->conname));
            fkconstraint->deferrable = conform->condeferrable;
            fkconstraint->initdeferred = conform->condeferred;
            fkconstraint->skip_validation = true;
            fkconstraint->initially_valid = true;
            /* a few irrelevant fields omitted here */
            fkconstraint->pktable = NULL;
            fkconstraint->fk_attrs = NIL;
            fkconstraint->pk_attrs = NIL;
            fkconstraint->fk_matchtype = conform->confmatchtype;
            fkconstraint->fk_upd_action = conform->confupdtype;
            fkconstraint->fk_del_action = conform->confdeltype;
            fkconstraint->fk_del_set_cols = NIL;
            fkconstraint->old_conpfeqop = NIL;
            fkconstraint->old_pktable_oid = InvalidOid;
            fkconstraint->location = -1;
 
            attmap = build_attrmap_by_name(RelationGetDescr(partRel),
                                           RelationGetDescr(rel),
                                           false);
            for (int i = 0; i < numfks; i++)
            {
                Form_pg_attribute att;
 
                att = TupleDescAttr(RelationGetDescr(partRel),
                                    attmap->attnums[conkey[i] - 1] - 1);
                fkconstraint->fk_attrs = lappend(fkconstraint->fk_attrs,
                                                 makeString(NameStr(att->attname)));
            }
 
            refdRel = table_open(fk->confrelid, AccessShareLock);
 
            addFkRecurseReferenced(fkconstraint, partRel,
                                   refdRel,
                                   conform->conindid,
                                   fk->conoid,
                                   numfks,
                                   confkey,
                                   conkey,
                                   conpfeqop,
                                   conppeqop,
                                   conffeqop,
                                   numfkdelsetcols,
                                   confdelsetcols,
                                   true,
                                   InvalidOid, InvalidOid,
                                   conform->conperiod);
            table_close(refdRel, AccessShareLock);
        }
 
        ReleaseSysCache(contup);
        ReleaseSysCache(parentConTup);
    }
    list_free_deep(fks);
    if (trigrel)
        table_close(trigrel, RowExclusiveLock);
 
    /*
     * Any sub-constraints that are in the referenced-side of a larger
     * constraint have to be removed.  This partition is no longer part of the
     * key space of the constraint.
     */
    foreach(cell, GetParentedForeignKeyRefs(partRel))
    {
        Oid         constrOid = lfirst_oid(cell);
        ObjectAddress constraint;
 
        ConstraintSetParentConstraint(constrOid, InvalidOid, InvalidOid);
        deleteDependencyRecordsForClass(ConstraintRelationId,
                                        constrOid,
                                        ConstraintRelationId,
                                        DEPENDENCY_INTERNAL);
        CommandCounterIncrement();
 
        ObjectAddressSet(constraint, ConstraintRelationId, constrOid);
        performDeletion(&constraint, DROP_RESTRICT, 0);
    }
 
    /* Now we can detach indexes */
    indexes = RelationGetIndexList(partRel);
    foreach(cell, indexes)
    {
        Oid         idxid = lfirst_oid(cell);
        Oid         parentidx;
        Relation    idx;
        Oid         constrOid;
        Oid         parentConstrOid;
 
        if (!has_superclass(idxid))
            continue;
 
        parentidx = get_partition_parent(idxid, false);
        Assert((IndexGetRelation(parentidx, false) == RelationGetRelid(rel)));
 
        idx = index_open(idxid, AccessExclusiveLock);
        IndexSetParentIndex(idx, InvalidOid);
 
        /*
         * If there's a constraint associated with the index, detach it too.
         * Careful: it is possible for a constraint index in a partition to be
         * the child of a non-constraint index, so verify whether the parent
         * index does actually have a constraint.
         */
        constrOid = get_relation_idx_constraint_oid(RelationGetRelid(partRel),
                                                    idxid);
        parentConstrOid = get_relation_idx_constraint_oid(RelationGetRelid(rel),
                                                          parentidx);
        if (OidIsValid(parentConstrOid) && OidIsValid(constrOid))
            ConstraintSetParentConstraint(constrOid, InvalidOid, InvalidOid);
 
        index_close(idx, NoLock);
    }
 
    /* Update pg_class tuple */
    classRel = table_open(RelationRelationId, RowExclusiveLock);
    tuple = SearchSysCacheCopy1(RELOID,
                                ObjectIdGetDatum(RelationGetRelid(partRel)));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u",
             RelationGetRelid(partRel));
    Assert(((Form_pg_class) GETSTRUCT(tuple))->relispartition);
 
    /* Clear relpartbound and reset relispartition */
    memset(new_val, 0, sizeof(new_val));
    memset(new_null, false, sizeof(new_null));
    memset(new_repl, false, sizeof(new_repl));
    new_val[Anum_pg_class_relpartbound - 1] = (Datum) 0;
    new_null[Anum_pg_class_relpartbound - 1] = true;
    new_repl[Anum_pg_class_relpartbound - 1] = true;
    newtuple = heap_modify_tuple(tuple, RelationGetDescr(classRel),
                                 new_val, new_null, new_repl);
 
    ((Form_pg_class) GETSTRUCT(newtuple))->relispartition = false;
    CatalogTupleUpdate(classRel, &newtuple->t_self, newtuple);
    heap_freetuple(newtuple);
    table_close(classRel, RowExclusiveLock);
 
    /*
     * Drop identity property from all identity columns of partition.
     */
    for (int attno = 0; attno < RelationGetNumberOfAttributes(partRel); attno++)
    {
        Form_pg_attribute attr = TupleDescAttr(partRel->rd_att, attno);
 
        if (!attr->attisdropped && attr->attidentity)
            ATExecDropIdentity(partRel, NameStr(attr->attname), false,
                               AccessExclusiveLock, true, true);
    }
 
    if (OidIsValid(defaultPartOid))
    {
        /*
         * If the relation being detached is the default partition itself,
         * remove it from the parent's pg_partitioned_table entry.
         *
         * If not, we must invalidate default partition's relcache entry, as
         * in StorePartitionBound: its partition constraint depends on every
         * other partition's partition constraint.
         */
        if (RelationGetRelid(partRel) == defaultPartOid)
            update_default_partition_oid(RelationGetRelid(rel), InvalidOid);
        else
            CacheInvalidateRelcacheByRelid(defaultPartOid);
    }
 
    /*
     * Invalidate the parent's relcache so that the partition is no longer
     * included in its partition descriptor.
     */
    CacheInvalidateRelcache(rel);
 
    /*
     * If the partition we just detached is partitioned itself, invalidate
     * relcache for all descendent partitions too to ensure that their
     * rd_partcheck expression trees are rebuilt; must lock partitions before
     * doing so, using the same lockmode as what partRel has been locked with
     * by the caller.
     */
    if (partRel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        List       *children;
 
        children = find_all_inheritors(RelationGetRelid(partRel),
                                       AccessExclusiveLock, NULL);
        foreach(cell, children)
        {
            CacheInvalidateRelcacheByRelid(lfirst_oid(cell));
        }
    }
}
 
/*
 * ALTER TABLE ... DETACH PARTITION ... FINALIZE
 *
 * To use when a DETACH PARTITION command previously did not run to
 * completion; this completes the detaching process.
 */
static ObjectAddress
ATExecDetachPartitionFinalize(Relation rel, RangeVar *name)
{
    Relation    partRel;
    ObjectAddress address;
    Snapshot    snap = GetActiveSnapshot();
 
    partRel = table_openrv(name, AccessExclusiveLock);
 
    /*
     * Wait until existing snapshots are gone.  This is important if the
     * second transaction of DETACH PARTITION CONCURRENTLY is canceled: the
     * user could immediately run DETACH FINALIZE without actually waiting for
     * existing transactions.  We must not complete the detach action until
     * all such queries are complete (otherwise we would present them with an
     * inconsistent view of catalogs).
     */
    WaitForOlderSnapshots(snap->xmin, false);
 
    DetachPartitionFinalize(rel, partRel, true, InvalidOid);
 
    ObjectAddressSet(address, RelationRelationId, RelationGetRelid(partRel));
 
    table_close(partRel, NoLock);
 
    return address;
}
 
/*
 * DetachAddConstraintIfNeeded
 *      Subroutine for ATExecDetachPartition.  Create a constraint that
 *      takes the place of the partition constraint, but avoid creating
 *      a dupe if an constraint already exists which implies the needed
 *      constraint.
 */
static void
DetachAddConstraintIfNeeded(List **wqueue, Relation partRel)
{
    List       *constraintExpr;
 
    constraintExpr = RelationGetPartitionQual(partRel);
    constraintExpr = (List *) eval_const_expressions(NULL, (Node *) constraintExpr);
 
    /*
     * Avoid adding a new constraint if the needed constraint is implied by an
     * existing constraint
     */
    if (!PartConstraintImpliedByRelConstraint(partRel, constraintExpr))
    {
        AlteredTableInfo *tab;
        Constraint *n;
 
        tab = ATGetQueueEntry(wqueue, partRel);
 
        /* Add constraint on partition, equivalent to the partition constraint */
        n = makeNode(Constraint);
        n->contype = CONSTR_CHECK;
        n->conname = NULL;
        n->location = -1;
        n->is_no_inherit = false;
        n->raw_expr = NULL;
        n->cooked_expr = nodeToString(make_ands_explicit(constraintExpr));
        n->initially_valid = true;
        n->skip_validation = true;
        /* It's a re-add, since it nominally already exists */
        ATAddCheckConstraint(wqueue, tab, partRel, n,
                             true, false, true, ShareUpdateExclusiveLock);
    }
}
 
/*
 * DropClonedTriggersFromPartition
 *      subroutine for ATExecDetachPartition to remove any triggers that were
 *      cloned to the partition when it was created-as-partition or attached.
 *      This undoes what CloneRowTriggersToPartition did.
 */
static void
DropClonedTriggersFromPartition(Oid partitionId)
{
    ScanKeyData skey;
    SysScanDesc scan;
    HeapTuple   trigtup;
    Relation    tgrel;
    ObjectAddresses *objects;
 
    objects = new_object_addresses();
 
    /*
     * Scan pg_trigger to search for all triggers on this rel.
     */
    ScanKeyInit(&skey, Anum_pg_trigger_tgrelid, BTEqualStrategyNumber,
                F_OIDEQ, ObjectIdGetDatum(partitionId));
    tgrel = table_open(TriggerRelationId, RowExclusiveLock);
    scan = systable_beginscan(tgrel, TriggerRelidNameIndexId,
                              true, NULL, 1, &skey);
    while (HeapTupleIsValid(trigtup = systable_getnext(scan)))
    {
        Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(trigtup);
        ObjectAddress trig;
 
        /* Ignore triggers that weren't cloned */
        if (!OidIsValid(pg_trigger->tgparentid))
            continue;
 
        /*
         * Ignore internal triggers that are implementation objects of foreign
         * keys, because these will be detached when the foreign keys
         * themselves are.
         */
        if (OidIsValid(pg_trigger->tgconstrrelid))
            continue;
 
        /*
         * This is ugly, but necessary: remove the dependency markings on the
         * trigger so that it can be removed.
         */
        deleteDependencyRecordsForClass(TriggerRelationId, pg_trigger->oid,
                                        TriggerRelationId,
                                        DEPENDENCY_PARTITION_PRI);
        deleteDependencyRecordsForClass(TriggerRelationId, pg_trigger->oid,
                                        RelationRelationId,
                                        DEPENDENCY_PARTITION_SEC);
 
        /* remember this trigger to remove it below */
        ObjectAddressSet(trig, TriggerRelationId, pg_trigger->oid);
        add_exact_object_address(&trig, objects);
    }
 
    /* make the dependency removal visible to the deletion below */
    CommandCounterIncrement();
    performMultipleDeletions(objects, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
 
    /* done */
    free_object_addresses(objects);
    systable_endscan(scan);
    table_close(tgrel, RowExclusiveLock);
}
 
/*
 * Before acquiring lock on an index, acquire the same lock on the owning
 * table.
 */
struct AttachIndexCallbackState
{
    Oid         partitionOid;
    Oid         parentTblOid;
    bool        lockedParentTbl;
};
 
static void
RangeVarCallbackForAttachIndex(const RangeVar *rv, Oid relOid, Oid oldRelOid,
                               void *arg)
{
    struct AttachIndexCallbackState *state;
    Form_pg_class classform;
    HeapTuple   tuple;
 
    state = (struct AttachIndexCallbackState *) arg;
 
    if (!state->lockedParentTbl)
    {
        LockRelationOid(state->parentTblOid, AccessShareLock);
        state->lockedParentTbl = true;
    }
 
    /*
     * If we previously locked some other heap, and the name we're looking up
     * no longer refers to an index on that relation, release the now-useless
     * lock.  XXX maybe we should do *after* we verify whether the index does
     * not actually belong to the same relation ...
     */
    if (relOid != oldRelOid && OidIsValid(state->partitionOid))
    {
        UnlockRelationOid(state->partitionOid, AccessShareLock);
        state->partitionOid = InvalidOid;
    }
 
    /* Didn't find a relation, so no need for locking or permission checks. */
    if (!OidIsValid(relOid))
        return;
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relOid));
    if (!HeapTupleIsValid(tuple))
        return;                 /* concurrently dropped, so nothing to do */
    classform = (Form_pg_class) GETSTRUCT(tuple);
    if (classform->relkind != RELKIND_PARTITIONED_INDEX &&
        classform->relkind != RELKIND_INDEX)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("\"%s\" is not an index", rv->relname)));
    ReleaseSysCache(tuple);
 
    /*
     * Since we need only examine the heap's tupledesc, an access share lock
     * on it (preventing any DDL) is sufficient.
     */
    state->partitionOid = IndexGetRelation(relOid, false);
    LockRelationOid(state->partitionOid, AccessShareLock);
}
 
/*
 * ALTER INDEX i1 ATTACH PARTITION i2
 */
static ObjectAddress
ATExecAttachPartitionIdx(List **wqueue, Relation parentIdx, RangeVar *name)
{
    Relation    partIdx;
    Relation    partTbl;
    Relation    parentTbl;
    ObjectAddress address;
    Oid         partIdxId;
    Oid         currParent;
    struct AttachIndexCallbackState state;
 
    /*
     * We need to obtain lock on the index 'name' to modify it, but we also
     * need to read its owning table's tuple descriptor -- so we need to lock
     * both.  To avoid deadlocks, obtain lock on the table before doing so on
     * the index.  Furthermore, we need to examine the parent table of the
     * partition, so lock that one too.
     */
    state.partitionOid = InvalidOid;
    state.parentTblOid = parentIdx->rd_index->indrelid;
    state.lockedParentTbl = false;
    partIdxId =
        RangeVarGetRelidExtended(name, AccessExclusiveLock, 0,
                                 RangeVarCallbackForAttachIndex,
                                 (void *) &state);
    /* Not there? */
    if (!OidIsValid(partIdxId))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("index \"%s\" does not exist", name->relname)));
 
    /* no deadlock risk: RangeVarGetRelidExtended already acquired the lock */
    partIdx = relation_open(partIdxId, AccessExclusiveLock);
 
    /* we already hold locks on both tables, so this is safe: */
    parentTbl = relation_open(parentIdx->rd_index->indrelid, AccessShareLock);
    partTbl = relation_open(partIdx->rd_index->indrelid, NoLock);
 
    ObjectAddressSet(address, RelationRelationId, RelationGetRelid(partIdx));
 
    /* Silently do nothing if already in the right state */
    currParent = partIdx->rd_rel->relispartition ?
        get_partition_parent(partIdxId, false) : InvalidOid;
    if (currParent != RelationGetRelid(parentIdx))
    {
        IndexInfo  *childInfo;
        IndexInfo  *parentInfo;
        AttrMap    *attmap;
        bool        found;
        int         i;
        PartitionDesc partDesc;
        Oid         constraintOid,
                    cldConstrId = InvalidOid;
 
        /*
         * If this partition already has an index attached, refuse the
         * operation.
         */
        refuseDupeIndexAttach(parentIdx, partIdx, partTbl);
 
        if (OidIsValid(currParent))
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("cannot attach index \"%s\" as a partition of index \"%s\"",
                            RelationGetRelationName(partIdx),
                            RelationGetRelationName(parentIdx)),
                     errdetail("Index \"%s\" is already attached to another index.",
                               RelationGetRelationName(partIdx))));
 
        /* Make sure it indexes a partition of the other index's table */
        partDesc = RelationGetPartitionDesc(parentTbl, true);
        found = false;
        for (i = 0; i < partDesc->nparts; i++)
        {
            if (partDesc->oids[i] == state.partitionOid)
            {
                found = true;
                break;
            }
        }
        if (!found)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("cannot attach index \"%s\" as a partition of index \"%s\"",
                            RelationGetRelationName(partIdx),
                            RelationGetRelationName(parentIdx)),
                     errdetail("Index \"%s\" is not an index on any partition of table \"%s\".",
                               RelationGetRelationName(partIdx),
                               RelationGetRelationName(parentTbl))));
 
        /* Ensure the indexes are compatible */
        childInfo = BuildIndexInfo(partIdx);
        parentInfo = BuildIndexInfo(parentIdx);
        attmap = build_attrmap_by_name(RelationGetDescr(partTbl),
                                       RelationGetDescr(parentTbl),
                                       false);
        if (!CompareIndexInfo(childInfo, parentInfo,
                              partIdx->rd_indcollation,
                              parentIdx->rd_indcollation,
                              partIdx->rd_opfamily,
                              parentIdx->rd_opfamily,
                              attmap))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("cannot attach index \"%s\" as a partition of index \"%s\"",
                            RelationGetRelationName(partIdx),
                            RelationGetRelationName(parentIdx)),
                     errdetail("The index definitions do not match.")));
 
        /*
         * If there is a constraint in the parent, make sure there is one in
         * the child too.
         */
        constraintOid = get_relation_idx_constraint_oid(RelationGetRelid(parentTbl),
                                                        RelationGetRelid(parentIdx));
 
        if (OidIsValid(constraintOid))
        {
            cldConstrId = get_relation_idx_constraint_oid(RelationGetRelid(partTbl),
                                                          partIdxId);
            if (!OidIsValid(cldConstrId))
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("cannot attach index \"%s\" as a partition of index \"%s\"",
                                RelationGetRelationName(partIdx),
                                RelationGetRelationName(parentIdx)),
                         errdetail("The index \"%s\" belongs to a constraint in table \"%s\" but no constraint exists for index \"%s\".",
                                   RelationGetRelationName(parentIdx),
                                   RelationGetRelationName(parentTbl),
                                   RelationGetRelationName(partIdx))));
        }
 
        /* All good -- do it */
        IndexSetParentIndex(partIdx, RelationGetRelid(parentIdx));
        if (OidIsValid(constraintOid))
            ConstraintSetParentConstraint(cldConstrId, constraintOid,
                                          RelationGetRelid(partTbl));
 
        free_attrmap(attmap);
 
        validatePartitionedIndex(parentIdx, parentTbl);
    }
 
    relation_close(parentTbl, AccessShareLock);
    /* keep these locks till commit */
    relation_close(partTbl, NoLock);
    relation_close(partIdx, NoLock);
 
    return address;
}
 
/*
 * Verify whether the given partition already contains an index attached
 * to the given partitioned index.  If so, raise an error.
 */
static void
refuseDupeIndexAttach(Relation parentIdx, Relation partIdx, Relation partitionTbl)
{
    Oid         existingIdx;
 
    existingIdx = index_get_partition(partitionTbl,
                                      RelationGetRelid(parentIdx));
    if (OidIsValid(existingIdx))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cannot attach index \"%s\" as a partition of index \"%s\"",
                        RelationGetRelationName(partIdx),
                        RelationGetRelationName(parentIdx)),
                 errdetail("Another index is already attached for partition \"%s\".",
                           RelationGetRelationName(partitionTbl))));
}
 
/*
 * Verify whether the set of attached partition indexes to a parent index on
 * a partitioned table is complete.  If it is, mark the parent index valid.
 *
 * This should be called each time a partition index is attached.
 */
static void
validatePartitionedIndex(Relation partedIdx, Relation partedTbl)
{
    Relation    inheritsRel;
    SysScanDesc scan;
    ScanKeyData key;
    int         tuples = 0;
    HeapTuple   inhTup;
    bool        updated = false;
 
    Assert(partedIdx->rd_rel->relkind == RELKIND_PARTITIONED_INDEX);
 
    /*
     * Scan pg_inherits for this parent index.  Count each valid index we find
     * (verifying the pg_index entry for each), and if we reach the total
     * amount we expect, we can mark this parent index as valid.
     */
    inheritsRel = table_open(InheritsRelationId, AccessShareLock);
    ScanKeyInit(&key, Anum_pg_inherits_inhparent,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetRelid(partedIdx)));
    scan = systable_beginscan(inheritsRel, InheritsParentIndexId, true,
                              NULL, 1, &key);
    while ((inhTup = systable_getnext(scan)) != NULL)
    {
        Form_pg_inherits inhForm = (Form_pg_inherits) GETSTRUCT(inhTup);
        HeapTuple   indTup;
        Form_pg_index indexForm;
 
        indTup = SearchSysCache1(INDEXRELID,
                                 ObjectIdGetDatum(inhForm->inhrelid));
        if (!HeapTupleIsValid(indTup))
            elog(ERROR, "cache lookup failed for index %u", inhForm->inhrelid);
        indexForm = (Form_pg_index) GETSTRUCT(indTup);
        if (indexForm->indisvalid)
            tuples += 1;
        ReleaseSysCache(indTup);
    }
 
    /* Done with pg_inherits */
    systable_endscan(scan);
    table_close(inheritsRel, AccessShareLock);
 
    /*
     * If we found as many inherited indexes as the partitioned table has
     * partitions, we're good; update pg_index to set indisvalid.
     */
    if (tuples == RelationGetPartitionDesc(partedTbl, true)->nparts)
    {
        Relation    idxRel;
        HeapTuple   indTup;
        Form_pg_index indexForm;
 
        idxRel = table_open(IndexRelationId, RowExclusiveLock);
        indTup = SearchSysCacheCopy1(INDEXRELID,
                                     ObjectIdGetDatum(RelationGetRelid(partedIdx)));
        if (!HeapTupleIsValid(indTup))
            elog(ERROR, "cache lookup failed for index %u",
                 RelationGetRelid(partedIdx));
        indexForm = (Form_pg_index) GETSTRUCT(indTup);
 
        indexForm->indisvalid = true;
        updated = true;
 
        CatalogTupleUpdate(idxRel, &indTup->t_self, indTup);
 
        table_close(idxRel, RowExclusiveLock);
        heap_freetuple(indTup);
    }
 
    /*
     * If this index is in turn a partition of a larger index, validating it
     * might cause the parent to become valid also.  Try that.
     */
    if (updated && partedIdx->rd_rel->relispartition)
    {
        Oid         parentIdxId,
                    parentTblId;
        Relation    parentIdx,
                    parentTbl;
 
        /* make sure we see the validation we just did */
        CommandCounterIncrement();
 
        parentIdxId = get_partition_parent(RelationGetRelid(partedIdx), false);
        parentTblId = get_partition_parent(RelationGetRelid(partedTbl), false);
        parentIdx = relation_open(parentIdxId, AccessExclusiveLock);
        parentTbl = relation_open(parentTblId, AccessExclusiveLock);
        Assert(!parentIdx->rd_index->indisvalid);
 
        validatePartitionedIndex(parentIdx, parentTbl);
 
        relation_close(parentIdx, AccessExclusiveLock);
        relation_close(parentTbl, AccessExclusiveLock);
    }
}
 
/*
 * Return an OID list of constraints that reference the given relation
 * that are marked as having a parent constraints.
 */
static List *
GetParentedForeignKeyRefs(Relation partition)
{
    Relation    pg_constraint;
    HeapTuple   tuple;
    SysScanDesc scan;
    ScanKeyData key[2];
    List       *constraints = NIL;
 
    /*
     * If no indexes, or no columns are referenceable by FKs, we can avoid the
     * scan.
     */
    if (RelationGetIndexList(partition) == NIL ||
        bms_is_empty(RelationGetIndexAttrBitmap(partition,
                                                INDEX_ATTR_BITMAP_KEY)))
        return NIL;
 
    /* Search for constraints referencing this table */
    pg_constraint = table_open(ConstraintRelationId, AccessShareLock);
    ScanKeyInit(&key[0],
                Anum_pg_constraint_confrelid, BTEqualStrategyNumber,
                F_OIDEQ, ObjectIdGetDatum(RelationGetRelid(partition)));
    ScanKeyInit(&key[1],
                Anum_pg_constraint_contype, BTEqualStrategyNumber,
                F_CHAREQ, CharGetDatum(CONSTRAINT_FOREIGN));
 
    /* XXX This is a seqscan, as we don't have a usable index */
    scan = systable_beginscan(pg_constraint, InvalidOid, true, NULL, 2, key);
    while ((tuple = systable_getnext(scan)) != NULL)
    {
        Form_pg_constraint constrForm = (Form_pg_constraint) GETSTRUCT(tuple);
 
        /*
         * We only need to process constraints that are part of larger ones.
         */
        if (!OidIsValid(constrForm->conparentid))
            continue;
 
        constraints = lappend_oid(constraints, constrForm->oid);
    }
 
    systable_endscan(scan);
    table_close(pg_constraint, AccessShareLock);
 
    return constraints;
}
 
/*
 * During DETACH PARTITION, verify that any foreign keys pointing to the
 * partitioned table would not become invalid.  An error is raised if any
 * referenced values exist.
 */
static void
ATDetachCheckNoForeignKeyRefs(Relation partition)
{
    List       *constraints;
    ListCell   *cell;
 
    constraints = GetParentedForeignKeyRefs(partition);
 
    foreach(cell, constraints)
    {
        Oid         constrOid = lfirst_oid(cell);
        HeapTuple   tuple;
        Form_pg_constraint constrForm;
        Relation    rel;
        Trigger     trig = {0};
 
        tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constrOid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for constraint %u", constrOid);
        constrForm = (Form_pg_constraint) GETSTRUCT(tuple);
 
        Assert(OidIsValid(constrForm->conparentid));
        Assert(constrForm->confrelid == RelationGetRelid(partition));
 
        /* prevent data changes into the referencing table until commit */
        rel = table_open(constrForm->conrelid, ShareLock);
 
        trig.tgoid = InvalidOid;
        trig.tgname = NameStr(constrForm->conname);
        trig.tgenabled = TRIGGER_FIRES_ON_ORIGIN;
        trig.tgisinternal = true;
        trig.tgconstrrelid = RelationGetRelid(partition);
        trig.tgconstrindid = constrForm->conindid;
        trig.tgconstraint = constrForm->oid;
        trig.tgdeferrable = false;
        trig.tginitdeferred = false;
        /* we needn't fill in remaining fields */
 
        RI_PartitionRemove_Check(&trig, rel, partition);
 
        ReleaseSysCache(tuple);
 
        table_close(rel, NoLock);
    }
}
 
/*
 * resolve column compression specification to compression method.
 */
static char
GetAttributeCompression(Oid atttypid, const char *compression)
{
    char        cmethod;
 
    if (compression == NULL || strcmp(compression, "default") == 0)
        return InvalidCompressionMethod;
 
    /*
     * To specify a nondefault method, the column data type must be toastable.
     * Note this says nothing about whether the column's attstorage setting
     * permits compression; we intentionally allow attstorage and
     * attcompression to be independent.  But with a non-toastable type,
     * attstorage could not be set to a value that would permit compression.
     *
     * We don't actually need to enforce this, since nothing bad would happen
     * if attcompression were non-default; it would never be consulted.  But
     * it seems more user-friendly to complain about a certainly-useless
     * attempt to set the property.
     */
    if (!TypeIsToastable(atttypid))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("column data type %s does not support compression",
                        format_type_be(atttypid))));
 
    cmethod = CompressionNameToMethod(compression);
    if (!CompressionMethodIsValid(cmethod))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid compression method \"%s\"", compression)));
 
    return cmethod;
}
 
/*
 * resolve column storage specification
 */
static char
GetAttributeStorage(Oid atttypid, const char *storagemode)
{
    char        cstorage = 0;
 
    if (pg_strcasecmp(storagemode, "plain") == 0)
        cstorage = TYPSTORAGE_PLAIN;
    else if (pg_strcasecmp(storagemode, "external") == 0)
        cstorage = TYPSTORAGE_EXTERNAL;
    else if (pg_strcasecmp(storagemode, "extended") == 0)
        cstorage = TYPSTORAGE_EXTENDED;
    else if (pg_strcasecmp(storagemode, "main") == 0)
        cstorage = TYPSTORAGE_MAIN;
    else if (pg_strcasecmp(storagemode, "default") == 0)
        cstorage = get_typstorage(atttypid);
    else
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid storage type \"%s\"",
                        storagemode)));
 
    /*
     * safety check: do not allow toasted storage modes unless column datatype
     * is TOAST-aware.
     */
    if (!(cstorage == TYPSTORAGE_PLAIN || TypeIsToastable(atttypid)))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("column data type %s can only have storage PLAIN",
                        format_type_be(atttypid))));
 
    return cstorage;
}