parse_utilcmd.c

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/*-------------------------------------------------------------------------
 *
 * parse_utilcmd.c
 *    Perform parse analysis work for various utility commands
 *
 * Formerly we did this work during parse_analyze() in analyze.c.  However
 * that is fairly unsafe in the presence of querytree caching, since any
 * database state that we depend on in making the transformations might be
 * obsolete by the time the utility command is executed; and utility commands
 * have no infrastructure for holding locks or rechecking plan validity.
 * Hence these functions are now called at the start of execution of their
 * respective utility commands.
 *
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *  src/backend/parser/parse_utilcmd.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/amapi.h"
#include "access/htup_details.h"
#include "access/relation.h"
#include "access/reloptions.h"
#include "access/table.h"
#include "access/toast_compression.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/namespace.h"
#include "catalog/pg_am.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_statistic_ext.h"
#include "catalog/pg_type.h"
#include "commands/comment.h"
#include "commands/defrem.h"
#include "commands/sequence.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/optimizer.h"
#include "parser/analyze.h"
#include "parser/parse_clause.h"
#include "parser/parse_coerce.h"
#include "parser/parse_collate.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "parser/parse_type.h"
#include "parser/parse_utilcmd.h"
#include "parser/parser.h"
#include "rewrite/rewriteManip.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/partcache.h"
#include "utils/rel.h"
#include "utils/ruleutils.h"
#include "utils/syscache.h"
#include "utils/typcache.h"


/* State shared by transformCreateStmt and its subroutines */
typedef struct
{
    ParseState *pstate;         /* overall parser state */
    const char *stmtType;       /* "CREATE [FOREIGN] TABLE" or "ALTER TABLE" */
    RangeVar   *relation;       /* relation to create */
    Relation    rel;            /* opened/locked rel, if ALTER */
    List       *inhRelations;   /* relations to inherit from */
    bool        isforeign;      /* true if CREATE/ALTER FOREIGN TABLE */
    bool        isalter;        /* true if altering existing table */
    List       *columns;        /* ColumnDef items */
    List       *ckconstraints;  /* CHECK constraints */
    List       *fkconstraints;  /* FOREIGN KEY constraints */
    List       *ixconstraints;  /* index-creating constraints */
    List       *likeclauses;    /* LIKE clauses that need post-processing */
    List       *extstats;       /* cloned extended statistics */
    List       *blist;          /* "before list" of things to do before
                                 * creating the table */
    List       *alist;          /* "after list" of things to do after creating
                                 * the table */
    IndexStmt  *pkey;           /* PRIMARY KEY index, if any */
    bool        ispartitioned;  /* true if table is partitioned */
    PartitionBoundSpec *partbound;  /* transformed FOR VALUES */
    bool        ofType;         /* true if statement contains OF typename */
} CreateStmtContext;

/* State shared by transformCreateSchemaStmt and its subroutines */
typedef struct
{
    const char *stmtType;       /* "CREATE SCHEMA" or "ALTER SCHEMA" */
    char       *schemaname;     /* name of schema */
    RoleSpec   *authrole;       /* owner of schema */
    List       *sequences;      /* CREATE SEQUENCE items */
    List       *tables;         /* CREATE TABLE items */
    List       *views;          /* CREATE VIEW items */
    List       *indexes;        /* CREATE INDEX items */
    List       *triggers;       /* CREATE TRIGGER items */
    List       *grants;         /* GRANT items */
} CreateSchemaStmtContext;


static void transformColumnDefinition(CreateStmtContext *cxt,
                                      ColumnDef *column);
static void transformTableConstraint(CreateStmtContext *cxt,
                                     Constraint *constraint);
static void transformTableLikeClause(CreateStmtContext *cxt,
                                     TableLikeClause *table_like_clause);
static void transformOfType(CreateStmtContext *cxt,
                            TypeName *ofTypename);
static CreateStatsStmt *generateClonedExtStatsStmt(RangeVar *heapRel,
                                                   Oid heapRelid, Oid source_statsid);
static List *get_collation(Oid collation, Oid actual_datatype);
static List *get_opclass(Oid opclass, Oid actual_datatype);
static void transformIndexConstraints(CreateStmtContext *cxt);
static IndexStmt *transformIndexConstraint(Constraint *constraint,
                                           CreateStmtContext *cxt);
static void transformExtendedStatistics(CreateStmtContext *cxt);
static void transformFKConstraints(CreateStmtContext *cxt,
                                   bool skipValidation,
                                   bool isAddConstraint);
static void transformCheckConstraints(CreateStmtContext *cxt,
                                      bool skipValidation);
static void transformConstraintAttrs(CreateStmtContext *cxt,
                                     List *constraintList);
static void transformColumnType(CreateStmtContext *cxt, ColumnDef *column);
static void setSchemaName(char *context_schema, char **stmt_schema_name);
static void transformPartitionCmd(CreateStmtContext *cxt, PartitionCmd *cmd);
static List *transformPartitionRangeBounds(ParseState *pstate, List *blist,
                                           Relation parent);
static void validateInfiniteBounds(ParseState *pstate, List *blist);
static Const *transformPartitionBoundValue(ParseState *pstate, Node *con,
                                           const char *colName, Oid colType, int32 colTypmod,
                                           Oid partCollation);


/*
 * transformCreateStmt -
 *    parse analysis for CREATE TABLE
 *
 * Returns a List of utility commands to be done in sequence.  One of these
 * will be the transformed CreateStmt, but there may be additional actions
 * to be done before and after the actual DefineRelation() call.
 * In addition to normal utility commands such as AlterTableStmt and
 * IndexStmt, the result list may contain TableLikeClause(s), representing
 * the need to perform additional parse analysis after DefineRelation().
 *
 * SQL allows constraints to be scattered all over, so thumb through
 * the columns and collect all constraints into one place.
 * If there are any implied indices (e.g. UNIQUE or PRIMARY KEY)
 * then expand those into multiple IndexStmt blocks.
 *    - thomas 1997-12-02
 */
List *
transformCreateStmt(CreateStmt *stmt, const char *queryString)
{
    ParseState *pstate;
    CreateStmtContext cxt;
    List       *result;
    List       *save_alist;
    ListCell   *elements;
    Oid         namespaceid;
    Oid         existing_relid;
    ParseCallbackState pcbstate;

    /* Set up pstate */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /*
     * Look up the creation namespace.  This also checks permissions on the
     * target namespace, locks it against concurrent drops, checks for a
     * preexisting relation in that namespace with the same name, and updates
     * stmt->relation->relpersistence if the selected namespace is temporary.
     */
    setup_parser_errposition_callback(&pcbstate, pstate,
                                      stmt->relation->location);
    namespaceid =
        RangeVarGetAndCheckCreationNamespace(stmt->relation, NoLock,
                                             &existing_relid);
    cancel_parser_errposition_callback(&pcbstate);

    /*
     * If the relation already exists and the user specified "IF NOT EXISTS",
     * bail out with a NOTICE.
     */
    if (stmt->if_not_exists && OidIsValid(existing_relid))
    {
        ereport(NOTICE,
                (errcode(ERRCODE_DUPLICATE_TABLE),
                 errmsg("relation \"%s\" already exists, skipping",
                        stmt->relation->relname)));
        return NIL;
    }

    /*
     * If the target relation name isn't schema-qualified, make it so.  This
     * prevents some corner cases in which added-on rewritten commands might
     * think they should apply to other relations that have the same name and
     * are earlier in the search path.  But a local temp table is effectively
     * specified to be in pg_temp, so no need for anything extra in that case.
     */
    if (stmt->relation->schemaname == NULL
        && stmt->relation->relpersistence != RELPERSISTENCE_TEMP)
        stmt->relation->schemaname = get_namespace_name(namespaceid);

    /* Set up CreateStmtContext */
    cxt.pstate = pstate;
    if (IsA(stmt, CreateForeignTableStmt))
    {
        cxt.stmtType = "CREATE FOREIGN TABLE";
        cxt.isforeign = true;
    }
    else
    {
        cxt.stmtType = "CREATE TABLE";
        cxt.isforeign = false;
    }
    cxt.relation = stmt->relation;
    cxt.rel = NULL;
    cxt.inhRelations = stmt->inhRelations;
    cxt.isalter = false;
    cxt.columns = NIL;
    cxt.ckconstraints = NIL;
    cxt.fkconstraints = NIL;
    cxt.ixconstraints = NIL;
    cxt.likeclauses = NIL;
    cxt.extstats = NIL;
    cxt.blist = NIL;
    cxt.alist = NIL;
    cxt.pkey = NULL;
    cxt.ispartitioned = stmt->partspec != NULL;
    cxt.partbound = stmt->partbound;
    cxt.ofType = (stmt->ofTypename != NULL);

    Assert(!stmt->ofTypename || !stmt->inhRelations);   /* grammar enforces */

    if (stmt->ofTypename)
        transformOfType(&cxt, stmt->ofTypename);

    if (stmt->partspec)
    {
        if (stmt->inhRelations && !stmt->partbound)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("cannot create partitioned table as inheritance child")));
    }

    /*
     * Run through each primary element in the table creation clause. Separate
     * column defs from constraints, and do preliminary analysis.
     */
    foreach(elements, stmt->tableElts)
    {
        Node       *element = lfirst(elements);

        switch (nodeTag(element))
        {
            case T_ColumnDef:
                transformColumnDefinition(&cxt, (ColumnDef *) element);
                break;

            case T_Constraint:
                transformTableConstraint(&cxt, (Constraint *) element);
                break;

            case T_TableLikeClause:
                transformTableLikeClause(&cxt, (TableLikeClause *) element);
                break;

            default:
                elog(ERROR, "unrecognized node type: %d",
                     (int) nodeTag(element));
                break;
        }
    }

    /*
     * Transfer anything we already have in cxt.alist into save_alist, to keep
     * it separate from the output of transformIndexConstraints.  (This may
     * not be necessary anymore, but we'll keep doing it to preserve the
     * historical order of execution of the alist commands.)
     */
    save_alist = cxt.alist;
    cxt.alist = NIL;

    Assert(stmt->constraints == NIL);

    /*
     * Postprocess constraints that give rise to index definitions.
     */
    transformIndexConstraints(&cxt);

    /*
     * Re-consideration of LIKE clauses should happen after creation of
     * indexes, but before creation of foreign keys.  This order is critical
     * because a LIKE clause may attempt to create a primary key.  If there's
     * also a pkey in the main CREATE TABLE list, creation of that will not
     * check for a duplicate at runtime (since index_check_primary_key()
     * expects that we rejected dups here).  Creation of the LIKE-generated
     * pkey behaves like ALTER TABLE ADD, so it will check, but obviously that
     * only works if it happens second.  On the other hand, we want to make
     * pkeys before foreign key constraints, in case the user tries to make a
     * self-referential FK.
     */
    cxt.alist = list_concat(cxt.alist, cxt.likeclauses);

    /*
     * Postprocess foreign-key constraints.
     */
    transformFKConstraints(&cxt, true, false);

    /*
     * Postprocess check constraints.
     *
     * For regular tables all constraints can be marked valid immediately,
     * because the table is new therefore empty. Not so for foreign tables.
     */
    transformCheckConstraints(&cxt, !cxt.isforeign);

    /*
     * Postprocess extended statistics.
     */
    transformExtendedStatistics(&cxt);

    /*
     * Output results.
     */
    stmt->tableElts = cxt.columns;
    stmt->constraints = cxt.ckconstraints;

    result = lappend(cxt.blist, stmt);
    result = list_concat(result, cxt.alist);
    result = list_concat(result, save_alist);

    return result;
}

/*
 * generateSerialExtraStmts
 *      Generate CREATE SEQUENCE and ALTER SEQUENCE ... OWNED BY statements
 *      to create the sequence for a serial or identity column.
 *
 * This includes determining the name the sequence will have.  The caller
 * can ask to get back the name components by passing non-null pointers
 * for snamespace_p and sname_p.
 */
static void
generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column,
                         Oid seqtypid, List *seqoptions,
                         bool for_identity, bool col_exists,
                         char **snamespace_p, char **sname_p)
{
    ListCell   *option;
    DefElem    *nameEl = NULL;
    Oid         snamespaceid;
    char       *snamespace;
    char       *sname;
    CreateSeqStmt *seqstmt;
    AlterSeqStmt *altseqstmt;
    List       *attnamelist;
    int         nameEl_idx = -1;

    /*
     * Determine namespace and name to use for the sequence.
     *
     * First, check if a sequence name was passed in as an option.  This is
     * used by pg_dump.  Else, generate a name.
     *
     * Although we use ChooseRelationName, it's not guaranteed that the
     * selected sequence name won't conflict; given sufficiently long field
     * names, two different serial columns in the same table could be assigned
     * the same sequence name, and we'd not notice since we aren't creating
     * the sequence quite yet.  In practice this seems quite unlikely to be a
     * problem, especially since few people would need two serial columns in
     * one table.
     */
    foreach(option, seqoptions)
    {
        DefElem    *defel = lfirst_node(DefElem, option);

        if (strcmp(defel->defname, "sequence_name") == 0)
        {
            if (nameEl)
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                         errmsg("conflicting or redundant options")));
            nameEl = defel;
            nameEl_idx = foreach_current_index(option);
        }
    }

    if (nameEl)
    {
        RangeVar   *rv = makeRangeVarFromNameList(castNode(List, nameEl->arg));

        snamespace = rv->schemaname;
        if (!snamespace)
        {
            /* Given unqualified SEQUENCE NAME, select namespace */
            if (cxt->rel)
                snamespaceid = RelationGetNamespace(cxt->rel);
            else
                snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
            snamespace = get_namespace_name(snamespaceid);
        }
        sname = rv->relname;
        /* Remove the SEQUENCE NAME item from seqoptions */
        seqoptions = list_delete_nth_cell(seqoptions, nameEl_idx);
    }
    else
    {
        if (cxt->rel)
            snamespaceid = RelationGetNamespace(cxt->rel);
        else
        {
            snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
            RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
        }
        snamespace = get_namespace_name(snamespaceid);
        sname = ChooseRelationName(cxt->relation->relname,
                                   column->colname,
                                   "seq",
                                   snamespaceid,
                                   false);
    }

    ereport(DEBUG1,
            (errmsg_internal("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
                             cxt->stmtType, sname,
                             cxt->relation->relname, column->colname)));

    /*
     * Build a CREATE SEQUENCE command to create the sequence object, and add
     * it to the list of things to be done before this CREATE/ALTER TABLE.
     */
    seqstmt = makeNode(CreateSeqStmt);
    seqstmt->for_identity = for_identity;
    seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
    seqstmt->options = seqoptions;

    /*
     * If a sequence data type was specified, add it to the options.  Prepend
     * to the list rather than append; in case a user supplied their own AS
     * clause, the "redundant options" error will point to their occurrence,
     * not our synthetic one.
     */
    if (seqtypid)
        seqstmt->options = lcons(makeDefElem("as",
                                             (Node *) makeTypeNameFromOid(seqtypid, -1),
                                             -1),
                                 seqstmt->options);

    /*
     * If this is ALTER ADD COLUMN, make sure the sequence will be owned by
     * the table's owner.  The current user might be someone else (perhaps a
     * superuser, or someone who's only a member of the owning role), but the
     * SEQUENCE OWNED BY mechanisms will bleat unless table and sequence have
     * exactly the same owning role.
     */
    if (cxt->rel)
        seqstmt->ownerId = cxt->rel->rd_rel->relowner;
    else
        seqstmt->ownerId = InvalidOid;

    cxt->blist = lappend(cxt->blist, seqstmt);

    /*
     * Store the identity sequence name that we decided on.  ALTER TABLE ...
     * ADD COLUMN ... IDENTITY needs this so that it can fill the new column
     * with values from the sequence, while the association of the sequence
     * with the table is not set until after the ALTER TABLE.
     */
    column->identitySequence = seqstmt->sequence;

    /*
     * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence as
     * owned by this column, and add it to the appropriate list of things to
     * be done along with this CREATE/ALTER TABLE.  In a CREATE or ALTER ADD
     * COLUMN, it must be done after the statement because we don't know the
     * column's attnum yet.  But if we do have the attnum (in AT_AddIdentity),
     * we can do the marking immediately, which improves some ALTER TABLE
     * behaviors.
     */
    altseqstmt = makeNode(AlterSeqStmt);
    altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
    attnamelist = list_make3(makeString(snamespace),
                             makeString(cxt->relation->relname),
                             makeString(column->colname));
    altseqstmt->options = list_make1(makeDefElem("owned_by",
                                                 (Node *) attnamelist, -1));
    altseqstmt->for_identity = for_identity;

    if (col_exists)
        cxt->blist = lappend(cxt->blist, altseqstmt);
    else
        cxt->alist = lappend(cxt->alist, altseqstmt);

    if (snamespace_p)
        *snamespace_p = snamespace;
    if (sname_p)
        *sname_p = sname;
}

/*
 * transformColumnDefinition -
 *      transform a single ColumnDef within CREATE TABLE
 *      Also used in ALTER TABLE ADD COLUMN
 */
static void
transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
{
    bool        is_serial;
    bool        saw_nullable;
    bool        saw_default;
    bool        saw_identity;
    bool        saw_generated;
    ListCell   *clist;

    cxt->columns = lappend(cxt->columns, column);

    /* Check for SERIAL pseudo-types */
    is_serial = false;
    if (column->typeName
        && list_length(column->typeName->names) == 1
        && !column->typeName->pct_type)
    {
        char       *typname = strVal(linitial(column->typeName->names));

        if (strcmp(typname, "smallserial") == 0 ||
            strcmp(typname, "serial2") == 0)
        {
            is_serial = true;
            column->typeName->names = NIL;
            column->typeName->typeOid = INT2OID;
        }
        else if (strcmp(typname, "serial") == 0 ||
                 strcmp(typname, "serial4") == 0)
        {
            is_serial = true;
            column->typeName->names = NIL;
            column->typeName->typeOid = INT4OID;
        }
        else if (strcmp(typname, "bigserial") == 0 ||
                 strcmp(typname, "serial8") == 0)
        {
            is_serial = true;
            column->typeName->names = NIL;
            column->typeName->typeOid = INT8OID;
        }

        /*
         * We have to reject "serial[]" explicitly, because once we've set
         * typeid, LookupTypeName won't notice arrayBounds.  We don't need any
         * special coding for serial(typmod) though.
         */
        if (is_serial && column->typeName->arrayBounds != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("array of serial is not implemented"),
                     parser_errposition(cxt->pstate,
                                        column->typeName->location)));
    }

    /* Do necessary work on the column type declaration */
    if (column->typeName)
        transformColumnType(cxt, column);

    /* Special actions for SERIAL pseudo-types */
    if (is_serial)
    {
        char       *snamespace;
        char       *sname;
        char       *qstring;
        A_Const    *snamenode;
        TypeCast   *castnode;
        FuncCall   *funccallnode;
        Constraint *constraint;

        generateSerialExtraStmts(cxt, column,
                                 column->typeName->typeOid, NIL,
                                 false, false,
                                 &snamespace, &sname);

        /*
         * Create appropriate constraints for SERIAL.  We do this in full,
         * rather than shortcutting, so that we will detect any conflicting
         * constraints the user wrote (like a different DEFAULT).
         *
         * Create an expression tree representing the function call
         * nextval('sequencename').  We cannot reduce the raw tree to cooked
         * form until after the sequence is created, but there's no need to do
         * so.
         */
        qstring = quote_qualified_identifier(snamespace, sname);
        snamenode = makeNode(A_Const);
        snamenode->val.type = T_String;
        snamenode->val.val.str = qstring;
        snamenode->location = -1;
        castnode = makeNode(TypeCast);
        castnode->typeName = SystemTypeName("regclass");
        castnode->arg = (Node *) snamenode;
        castnode->location = -1;
        funccallnode = makeFuncCall(SystemFuncName("nextval"),
                                    list_make1(castnode),
                                    COERCE_EXPLICIT_CALL,
                                    -1);
        constraint = makeNode(Constraint);
        constraint->contype = CONSTR_DEFAULT;
        constraint->location = -1;
        constraint->raw_expr = (Node *) funccallnode;
        constraint->cooked_expr = NULL;
        column->constraints = lappend(column->constraints, constraint);

        constraint = makeNode(Constraint);
        constraint->contype = CONSTR_NOTNULL;
        constraint->location = -1;
        column->constraints = lappend(column->constraints, constraint);
    }

    /* Process column constraints, if any... */
    transformConstraintAttrs(cxt, column->constraints);

    saw_nullable = false;
    saw_default = false;
    saw_identity = false;
    saw_generated = false;

    foreach(clist, column->constraints)
    {
        Constraint *constraint = lfirst_node(Constraint, clist);

        switch (constraint->contype)
        {
            case CONSTR_NULL:
                if (saw_nullable && column->is_not_null)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
                                    column->colname, cxt->relation->relname),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                column->is_not_null = false;
                saw_nullable = true;
                break;

            case CONSTR_NOTNULL:
                if (saw_nullable && !column->is_not_null)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
                                    column->colname, cxt->relation->relname),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                column->is_not_null = true;
                saw_nullable = true;
                break;

            case CONSTR_DEFAULT:
                if (saw_default)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple default values specified for column \"%s\" of table \"%s\"",
                                    column->colname, cxt->relation->relname),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                column->raw_default = constraint->raw_expr;
                Assert(constraint->cooked_expr == NULL);
                saw_default = true;
                break;

            case CONSTR_IDENTITY:
                {
                    Type        ctype;
                    Oid         typeOid;

                    if (cxt->ofType)
                        ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("identity columns are not supported on typed tables")));
                    if (cxt->partbound)
                        ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("identity columns are not supported on partitions")));

                    ctype = typenameType(cxt->pstate, column->typeName, NULL);
                    typeOid = ((Form_pg_type) GETSTRUCT(ctype))->oid;
                    ReleaseSysCache(ctype);

                    if (saw_identity)
                        ereport(ERROR,
                                (errcode(ERRCODE_SYNTAX_ERROR),
                                 errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
                                        column->colname, cxt->relation->relname),
                                 parser_errposition(cxt->pstate,
                                                    constraint->location)));

                    generateSerialExtraStmts(cxt, column,
                                             typeOid, constraint->options,
                                             true, false,
                                             NULL, NULL);

                    column->identity = constraint->generated_when;
                    saw_identity = true;

                    /* An identity column is implicitly NOT NULL */
                    if (saw_nullable && !column->is_not_null)
                        ereport(ERROR,
                                (errcode(ERRCODE_SYNTAX_ERROR),
                                 errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
                                        column->colname, cxt->relation->relname),
                                 parser_errposition(cxt->pstate,
                                                    constraint->location)));
                    column->is_not_null = true;
                    saw_nullable = true;
                    break;
                }

            case CONSTR_GENERATED:
                if (cxt->ofType)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("generated columns are not supported on typed tables")));
                if (cxt->partbound)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("generated columns are not supported on partitions")));

                if (saw_generated)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple generation clauses specified for column \"%s\" of table \"%s\"",
                                    column->colname, cxt->relation->relname),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                column->generated = ATTRIBUTE_GENERATED_STORED;
                column->raw_default = constraint->raw_expr;
                Assert(constraint->cooked_expr == NULL);
                saw_generated = true;
                break;

            case CONSTR_CHECK:
                cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
                break;

            case CONSTR_PRIMARY:
                if (cxt->isforeign)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("primary key constraints are not supported on foreign tables"),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                /* FALL THRU */

            case CONSTR_UNIQUE:
                if (cxt->isforeign)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("unique constraints are not supported on foreign tables"),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                if (constraint->keys == NIL)
                    constraint->keys = list_make1(makeString(column->colname));
                cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
                break;

            case CONSTR_EXCLUSION:
                /* grammar does not allow EXCLUDE as a column constraint */
                elog(ERROR, "column exclusion constraints are not supported");
                break;

            case CONSTR_FOREIGN:
                if (cxt->isforeign)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("foreign key constraints are not supported on foreign tables"),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));

                /*
                 * Fill in the current attribute's name and throw it into the
                 * list of FK constraints to be processed later.
                 */
                constraint->fk_attrs = list_make1(makeString(column->colname));
                cxt->fkconstraints = lappend(cxt->fkconstraints, constraint);
                break;

            case CONSTR_ATTR_DEFERRABLE:
            case CONSTR_ATTR_NOT_DEFERRABLE:
            case CONSTR_ATTR_DEFERRED:
            case CONSTR_ATTR_IMMEDIATE:
                /* transformConstraintAttrs took care of these */
                break;

            default:
                elog(ERROR, "unrecognized constraint type: %d",
                     constraint->contype);
                break;
        }

        if (saw_default && saw_identity)
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
                            column->colname, cxt->relation->relname),
                     parser_errposition(cxt->pstate,
                                        constraint->location)));

        if (saw_default && saw_generated)
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("both default and generation expression specified for column \"%s\" of table \"%s\"",
                            column->colname, cxt->relation->relname),
                     parser_errposition(cxt->pstate,
                                        constraint->location)));

        if (saw_identity && saw_generated)
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("both identity and generation expression specified for column \"%s\" of table \"%s\"",
                            column->colname, cxt->relation->relname),
                     parser_errposition(cxt->pstate,
                                        constraint->location)));
    }

    /*
     * If needed, generate ALTER FOREIGN TABLE ALTER COLUMN statement to add
     * per-column foreign data wrapper options to this column after creation.
     */
    if (column->fdwoptions != NIL)
    {
        AlterTableStmt *stmt;
        AlterTableCmd *cmd;

        cmd = makeNode(AlterTableCmd);
        cmd->subtype = AT_AlterColumnGenericOptions;
        cmd->name = column->colname;
        cmd->def = (Node *) column->fdwoptions;
        cmd->behavior = DROP_RESTRICT;
        cmd->missing_ok = false;

        stmt = makeNode(AlterTableStmt);
        stmt->relation = cxt->relation;
        stmt->cmds = NIL;
        stmt->objtype = OBJECT_FOREIGN_TABLE;
        stmt->cmds = lappend(stmt->cmds, cmd);

        cxt->alist = lappend(cxt->alist, stmt);
    }
}

/*
 * transformTableConstraint
 *      transform a Constraint node within CREATE TABLE or ALTER TABLE
 */
static void
transformTableConstraint(CreateStmtContext *cxt, Constraint *constraint)
{
    switch (constraint->contype)
    {
        case CONSTR_PRIMARY:
            if (cxt->isforeign)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("primary key constraints are not supported on foreign tables"),
                         parser_errposition(cxt->pstate,
                                            constraint->location)));
            cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
            break;

        case CONSTR_UNIQUE:
            if (cxt->isforeign)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("unique constraints are not supported on foreign tables"),
                         parser_errposition(cxt->pstate,
                                            constraint->location)));
            cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
            break;

        case CONSTR_EXCLUSION:
            if (cxt->isforeign)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("exclusion constraints are not supported on foreign tables"),
                         parser_errposition(cxt->pstate,
                                            constraint->location)));
            if (cxt->ispartitioned)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("exclusion constraints are not supported on partitioned tables"),
                         parser_errposition(cxt->pstate,
                                            constraint->location)));
            cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
            break;

        case CONSTR_CHECK:
            cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
            break;

        case CONSTR_FOREIGN:
            if (cxt->isforeign)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("foreign key constraints are not supported on foreign tables"),
                         parser_errposition(cxt->pstate,
                                            constraint->location)));
            cxt->fkconstraints = lappend(cxt->fkconstraints, constraint);
            break;

        case CONSTR_NULL:
        case CONSTR_NOTNULL:
        case CONSTR_DEFAULT:
        case CONSTR_ATTR_DEFERRABLE:
        case CONSTR_ATTR_NOT_DEFERRABLE:
        case CONSTR_ATTR_DEFERRED:
        case CONSTR_ATTR_IMMEDIATE:
            elog(ERROR, "invalid context for constraint type %d",
                 constraint->contype);
            break;

        default:
            elog(ERROR, "unrecognized constraint type: %d",
                 constraint->contype);
            break;
    }
}

/*
 * transformTableLikeClause
 *
 * Change the LIKE <srctable> portion of a CREATE TABLE statement into
 * column definitions that recreate the user defined column portions of
 * <srctable>.  Also, if there are any LIKE options that we can't fully
 * process at this point, add the TableLikeClause to cxt->likeclauses, which
 * will cause utility.c to call expandTableLikeClause() after the new
 * table has been created.
 */
static void
transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_clause)
{
    AttrNumber  parent_attno;
    Relation    relation;
    TupleDesc   tupleDesc;
    AclResult   aclresult;
    char       *comment;
    ParseCallbackState pcbstate;

    setup_parser_errposition_callback(&pcbstate, cxt->pstate,
                                      table_like_clause->relation->location);

    /* we could support LIKE in many cases, but worry about it another day */
    if (cxt->isforeign)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("LIKE is not supported for creating foreign tables")));

    /* Open the relation referenced by the LIKE clause */
    relation = relation_openrv(table_like_clause->relation, AccessShareLock);

    if (relation->rd_rel->relkind != RELKIND_RELATION &&
        relation->rd_rel->relkind != RELKIND_VIEW &&
        relation->rd_rel->relkind != RELKIND_MATVIEW &&
        relation->rd_rel->relkind != RELKIND_COMPOSITE_TYPE &&
        relation->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
        relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a table, view, materialized view, composite type, or foreign table",
                        RelationGetRelationName(relation))));

    cancel_parser_errposition_callback(&pcbstate);

    /*
     * Check for privileges
     */
    if (relation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
    {
        aclresult = pg_type_aclcheck(relation->rd_rel->reltype, GetUserId(),
                                     ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, OBJECT_TYPE,
                           RelationGetRelationName(relation));
    }
    else
    {
        aclresult = pg_class_aclcheck(RelationGetRelid(relation), GetUserId(),
                                      ACL_SELECT);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, get_relkind_objtype(relation->rd_rel->relkind),
                           RelationGetRelationName(relation));
    }

    tupleDesc = RelationGetDescr(relation);

    /*
     * Insert the copied attributes into the cxt for the new table definition.
     * We must do this now so that they appear in the table in the relative
     * position where the LIKE clause is, as required by SQL99.
     */
    for (parent_attno = 1; parent_attno <= tupleDesc->natts;
         parent_attno++)
    {
        Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
                                                    parent_attno - 1);
        char       *attributeName = NameStr(attribute->attname);
        ColumnDef  *def;

        /*
         * Ignore dropped columns in the parent.
         */
        if (attribute->attisdropped)
            continue;

        /*
         * Create a new column, which is marked as NOT inherited.
         *
         * For constraints, ONLY the NOT NULL constraint is inherited by the
         * new column definition per SQL99.
         */
        def = makeNode(ColumnDef);
        def->colname = pstrdup(attributeName);
        def->typeName = makeTypeNameFromOid(attribute->atttypid,
                                            attribute->atttypmod);
        def->inhcount = 0;
        def->is_local = true;
        def->is_not_null = attribute->attnotnull;
        def->is_from_type = false;
        def->storage = 0;
        def->raw_default = NULL;
        def->cooked_default = NULL;
        def->collClause = NULL;
        def->collOid = attribute->attcollation;
        def->constraints = NIL;
        def->location = -1;

        /*
         * Add to column list
         */
        cxt->columns = lappend(cxt->columns, def);

        /*
         * Although we don't transfer the column's default/generation
         * expression now, we need to mark it GENERATED if appropriate.
         */
        if (attribute->atthasdef && attribute->attgenerated &&
            (table_like_clause->options & CREATE_TABLE_LIKE_GENERATED))
            def->generated = attribute->attgenerated;

        /*
         * Copy identity if requested
         */
        if (attribute->attidentity &&
            (table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
        {
            Oid         seq_relid;
            List       *seq_options;

            /*
             * find sequence owned by old column; extract sequence parameters;
             * build new create sequence command
             */
            seq_relid = getIdentitySequence(RelationGetRelid(relation), attribute->attnum, false);
            seq_options = sequence_options(seq_relid);
            generateSerialExtraStmts(cxt, def,
                                     InvalidOid, seq_options,
                                     true, false,
                                     NULL, NULL);
            def->identity = attribute->attidentity;
        }

        /* Likewise, copy storage if requested */
        if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
            def->storage = attribute->attstorage;
        else
            def->storage = 0;

        /* Likewise, copy compression if requested */
        if ((table_like_clause->options & CREATE_TABLE_LIKE_COMPRESSION) != 0
            && CompressionMethodIsValid(attribute->attcompression))
            def->compression =
                pstrdup(GetCompressionMethodName(attribute->attcompression));
        else
            def->compression = NULL;

        /* Likewise, copy comment if requested */
        if ((table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS) &&
            (comment = GetComment(attribute->attrelid,
                                  RelationRelationId,
                                  attribute->attnum)) != NULL)
        {
            CommentStmt *stmt = makeNode(CommentStmt);

            stmt->objtype = OBJECT_COLUMN;
            stmt->object = (Node *) list_make3(makeString(cxt->relation->schemaname),
                                               makeString(cxt->relation->relname),
                                               makeString(def->colname));
            stmt->comment = comment;

            cxt->alist = lappend(cxt->alist, stmt);
        }
    }

    /*
     * We cannot yet deal with defaults, CHECK constraints, or indexes, since
     * we don't yet know what column numbers the copied columns will have in
     * the finished table.  If any of those options are specified, add the
     * LIKE clause to cxt->likeclauses so that expandTableLikeClause will be
     * called after we do know that.  Also, remember the relation OID so that
     * expandTableLikeClause is certain to open the same table.
     */
    if (table_like_clause->options &
        (CREATE_TABLE_LIKE_DEFAULTS |
         CREATE_TABLE_LIKE_GENERATED |
         CREATE_TABLE_LIKE_CONSTRAINTS |
         CREATE_TABLE_LIKE_INDEXES))
    {
        table_like_clause->relationOid = RelationGetRelid(relation);
        cxt->likeclauses = lappend(cxt->likeclauses, table_like_clause);
    }

    /*
     * We may copy extended statistics if requested, since the representation
     * of CreateStatsStmt doesn't depend on column numbers.
     */
    if (table_like_clause->options & CREATE_TABLE_LIKE_STATISTICS)
    {
        List       *parent_extstats;
        ListCell   *l;

        parent_extstats = RelationGetStatExtList(relation);

        foreach(l, parent_extstats)
        {
            Oid         parent_stat_oid = lfirst_oid(l);
            CreateStatsStmt *stats_stmt;

            stats_stmt = generateClonedExtStatsStmt(cxt->relation,
                                                    RelationGetRelid(relation),
                                                    parent_stat_oid);

            /* Copy comment on statistics object, if requested */
            if (table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS)
            {
                comment = GetComment(parent_stat_oid, StatisticExtRelationId, 0);

                /*
                 * We make use of CreateStatsStmt's stxcomment option, so as
                 * not to need to know now what name the statistics will have.
                 */
                stats_stmt->stxcomment = comment;
            }

            cxt->extstats = lappend(cxt->extstats, stats_stmt);
        }

        list_free(parent_extstats);
    }

    /*
     * Close the parent rel, but keep our AccessShareLock on it until xact
     * commit.  That will prevent someone else from deleting or ALTERing the
     * parent before we can run expandTableLikeClause.
     */
    table_close(relation, NoLock);
}

/*
 * expandTableLikeClause
 *
 * Process LIKE options that require knowing the final column numbers
 * assigned to the new table's columns.  This executes after we have
 * run DefineRelation for the new table.  It returns a list of utility
 * commands that should be run to generate indexes etc.
 */
List *
expandTableLikeClause(RangeVar *heapRel, TableLikeClause *table_like_clause)
{
    List       *result = NIL;
    List       *atsubcmds = NIL;
    AttrNumber  parent_attno;
    Relation    relation;
    Relation    childrel;
    TupleDesc   tupleDesc;
    TupleConstr *constr;
    AttrMap    *attmap;
    char       *comment;

    /*
     * Open the relation referenced by the LIKE clause.  We should still have
     * the table lock obtained by transformTableLikeClause (and this'll throw
     * an assertion failure if not).  Hence, no need to recheck privileges
     * etc.  We must open the rel by OID not name, to be sure we get the same
     * table.
     */
    if (!OidIsValid(table_like_clause->relationOid))
        elog(ERROR, "expandTableLikeClause called on untransformed LIKE clause");

    relation = relation_open(table_like_clause->relationOid, NoLock);

    tupleDesc = RelationGetDescr(relation);
    constr = tupleDesc->constr;

    /*
     * Open the newly-created child relation; we have lock on that too.
     */
    childrel = relation_openrv(heapRel, NoLock);

    /*
     * Construct a map from the LIKE relation's attnos to the child rel's.
     * This re-checks type match etc, although it shouldn't be possible to
     * have a failure since both tables are locked.
     */
    attmap = build_attrmap_by_name(RelationGetDescr(childrel),
                                   tupleDesc);

    /*
     * Process defaults, if required.
     */
    if ((table_like_clause->options &
         (CREATE_TABLE_LIKE_DEFAULTS | CREATE_TABLE_LIKE_GENERATED)) &&
        constr != NULL)
    {
        for (parent_attno = 1; parent_attno <= tupleDesc->natts;
             parent_attno++)
        {
            Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
                                                        parent_attno - 1);

            /*
             * Ignore dropped columns in the parent.
             */
            if (attribute->attisdropped)
                continue;

            /*
             * Copy default, if present and it should be copied.  We have
             * separate options for plain default expressions and GENERATED
             * defaults.
             */
            if (attribute->atthasdef &&
                (attribute->attgenerated ?
                 (table_like_clause->options & CREATE_TABLE_LIKE_GENERATED) :
                 (table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS)))
            {
                Node       *this_default = NULL;
                AttrDefault *attrdef = constr->defval;
                AlterTableCmd *atsubcmd;
                bool        found_whole_row;

                /* Find default in constraint structure */
                for (int i = 0; i < constr->num_defval; i++)
                {
                    if (attrdef[i].adnum == parent_attno)
                    {
                        this_default = stringToNode(attrdef[i].adbin);
                        break;
                    }
                }
                if (this_default == NULL)
                    elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
                         parent_attno, RelationGetRelationName(relation));

                atsubcmd = makeNode(AlterTableCmd);
                atsubcmd->subtype = AT_CookedColumnDefault;
                atsubcmd->num = attmap->attnums[parent_attno - 1];
                atsubcmd->def = map_variable_attnos(this_default,
                                                    1, 0,
                                                    attmap,
                                                    InvalidOid,
                                                    &found_whole_row);

                /*
                 * Prevent this for the same reason as for constraints below.
                 * Note that defaults cannot contain any vars, so it's OK that
                 * the error message refers to generated columns.
                 */
                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\".",
                                       NameStr(attribute->attname),
                                       RelationGetRelationName(relation))));

                atsubcmds = lappend(atsubcmds, atsubcmd);
            }
        }
    }

    /*
     * Copy CHECK constraints if requested, being careful to adjust attribute
     * numbers so they match the child.
     */
    if ((table_like_clause->options & CREATE_TABLE_LIKE_CONSTRAINTS) &&
        constr != NULL)
    {
        int         ccnum;

        for (ccnum = 0; ccnum < constr->num_check; ccnum++)
        {
            char       *ccname = constr->check[ccnum].ccname;
            char       *ccbin = constr->check[ccnum].ccbin;
            bool        ccnoinherit = constr->check[ccnum].ccnoinherit;
            Node       *ccbin_node;
            bool        found_whole_row;
            Constraint *n;
            AlterTableCmd *atsubcmd;

            ccbin_node = map_variable_attnos(stringToNode(ccbin),
                                             1, 0,
                                             attmap,
                                             InvalidOid, &found_whole_row);

            /*
             * We reject whole-row variables because the whole point of LIKE
             * is that the new table's rowtype might later diverge from the
             * parent's.  So, while translation might be possible right now,
             * it wouldn't be possible to guarantee it would work in future.
             */
            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\".",
                                   ccname,
                                   RelationGetRelationName(relation))));

            n = makeNode(Constraint);
            n->contype = CONSTR_CHECK;
            n->conname = pstrdup(ccname);
            n->location = -1;
            n->is_no_inherit = ccnoinherit;
            n->raw_expr = NULL;
            n->cooked_expr = nodeToString(ccbin_node);

            /* We can skip validation, since the new table should be empty. */
            n->skip_validation = true;
            n->initially_valid = true;

            atsubcmd = makeNode(AlterTableCmd);
            atsubcmd->subtype = AT_AddConstraint;
            atsubcmd->def = (Node *) n;
            atsubcmds = lappend(atsubcmds, atsubcmd);

            /* Copy comment on constraint */
            if ((table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS) &&
                (comment = GetComment(get_relation_constraint_oid(RelationGetRelid(relation),
                                                                  n->conname, false),
                                      ConstraintRelationId,
                                      0)) != NULL)
            {
                CommentStmt *stmt = makeNode(CommentStmt);

                stmt->objtype = OBJECT_TABCONSTRAINT;
                stmt->object = (Node *) list_make3(makeString(heapRel->schemaname),
                                                   makeString(heapRel->relname),
                                                   makeString(n->conname));
                stmt->comment = comment;

                result = lappend(result, stmt);
            }
        }
    }

    /*
     * If we generated any ALTER TABLE actions above, wrap them into a single
     * ALTER TABLE command.  Stick it at the front of the result, so it runs
     * before any CommentStmts we made above.
     */
    if (atsubcmds)
    {
        AlterTableStmt *atcmd = makeNode(AlterTableStmt);

        atcmd->relation = copyObject(heapRel);
        atcmd->cmds = atsubcmds;
        atcmd->objtype = OBJECT_TABLE;
        atcmd->missing_ok = false;
        result = lcons(atcmd, result);
    }

    /*
     * Process indexes if required.
     */
    if ((table_like_clause->options & CREATE_TABLE_LIKE_INDEXES) &&
        relation->rd_rel->relhasindex)
    {
        List       *parent_indexes;
        ListCell   *l;

        parent_indexes = RelationGetIndexList(relation);

        foreach(l, parent_indexes)
        {
            Oid         parent_index_oid = lfirst_oid(l);
            Relation    parent_index;
            IndexStmt  *index_stmt;

            parent_index = index_open(parent_index_oid, AccessShareLock);

            /* Build CREATE INDEX statement to recreate the parent_index */
            index_stmt = generateClonedIndexStmt(heapRel,
                                                 parent_index,
                                                 attmap,
                                                 NULL);

            /* Copy comment on index, if requested */
            if (table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS)
            {
                comment = GetComment(parent_index_oid, RelationRelationId, 0);

                /*
                 * We make use of IndexStmt's idxcomment option, so as not to
                 * need to know now what name the index will have.
                 */
                index_stmt->idxcomment = comment;
            }

            result = lappend(result, index_stmt);

            index_close(parent_index, AccessShareLock);
        }
    }

    /* Done with child rel */
    table_close(childrel, NoLock);

    /*
     * Close the parent rel, but keep our AccessShareLock 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);

    return result;
}

static void
transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
{
    HeapTuple   tuple;
    TupleDesc   tupdesc;
    int         i;
    Oid         ofTypeId;

    AssertArg(ofTypename);

    tuple = typenameType(NULL, ofTypename, NULL);
    check_of_type(tuple);
    ofTypeId = ((Form_pg_type) GETSTRUCT(tuple))->oid;
    ofTypename->typeOid = ofTypeId; /* cached for later */

    tupdesc = lookup_rowtype_tupdesc(ofTypeId, -1);
    for (i = 0; i < tupdesc->natts; i++)
    {
        Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
        ColumnDef  *n;

        if (attr->attisdropped)
            continue;

        n = makeNode(ColumnDef);
        n->colname = pstrdup(NameStr(attr->attname));
        n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod);
        n->inhcount = 0;
        n->is_local = true;
        n->is_not_null = false;
        n->is_from_type = true;
        n->storage = 0;
        n->raw_default = NULL;
        n->cooked_default = NULL;
        n->collClause = NULL;
        n->collOid = attr->attcollation;
        n->constraints = NIL;
        n->location = -1;
        cxt->columns = lappend(cxt->columns, n);
    }
    DecrTupleDescRefCount(tupdesc);

    ReleaseSysCache(tuple);
}

/*
 * Generate an IndexStmt node using information from an already existing index
 * "source_idx".
 *
 * heapRel is stored into the IndexStmt's relation field, but we don't use it
 * otherwise; some callers pass NULL, if they don't need it to be valid.
 * (The target relation might not exist yet, so we mustn't try to access it.)
 *
 * Attribute numbers in expression Vars are adjusted according to attmap.
 *
 * If constraintOid isn't NULL, we store the OID of any constraint associated
 * with the index there.
 *
 * Unlike transformIndexConstraint, we don't make any effort to force primary
 * key columns to be NOT NULL.  The larger cloning process this is part of
 * should have cloned their NOT NULL status separately (and DefineIndex will
 * complain if that fails to happen).
 */
IndexStmt *
generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
                        const AttrMap *attmap,
                        Oid *constraintOid)
{
    Oid         source_relid = RelationGetRelid(source_idx);
    HeapTuple   ht_idxrel;
    HeapTuple   ht_idx;
    HeapTuple   ht_am;
    Form_pg_class idxrelrec;
    Form_pg_index idxrec;
    Form_pg_am  amrec;
    oidvector  *indcollation;
    oidvector  *indclass;
    IndexStmt  *index;
    List       *indexprs;
    ListCell   *indexpr_item;
    Oid         indrelid;
    int         keyno;
    Oid         keycoltype;
    Datum       datum;
    bool        isnull;

    if (constraintOid)
        *constraintOid = InvalidOid;

    /*
     * Fetch pg_class tuple of source index.  We can't use the copy in the
     * relcache entry because it doesn't include optional fields.
     */
    ht_idxrel = SearchSysCache1(RELOID, ObjectIdGetDatum(source_relid));
    if (!HeapTupleIsValid(ht_idxrel))
        elog(ERROR, "cache lookup failed for relation %u", source_relid);
    idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);

    /* Fetch pg_index tuple for source index from relcache entry */
    ht_idx = source_idx->rd_indextuple;
    idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
    indrelid = idxrec->indrelid;

    /* Fetch the pg_am tuple of the index' access method */
    ht_am = SearchSysCache1(AMOID, ObjectIdGetDatum(idxrelrec->relam));
    if (!HeapTupleIsValid(ht_am))
        elog(ERROR, "cache lookup failed for access method %u",
             idxrelrec->relam);
    amrec = (Form_pg_am) GETSTRUCT(ht_am);

    /* Extract indcollation from the pg_index tuple */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indcollation, &isnull);
    Assert(!isnull);
    indcollation = (oidvector *) DatumGetPointer(datum);

    /* Extract indclass from the pg_index tuple */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indclass, &isnull);
    Assert(!isnull);
    indclass = (oidvector *) DatumGetPointer(datum);

    /* Begin building the IndexStmt */
    index = makeNode(IndexStmt);
    index->relation = heapRel;
    index->accessMethod = pstrdup(NameStr(amrec->amname));
    if (OidIsValid(idxrelrec->reltablespace))
        index->tableSpace = get_tablespace_name(idxrelrec->reltablespace);
    else
        index->tableSpace = NULL;
    index->excludeOpNames = NIL;
    index->idxcomment = NULL;
    index->indexOid = InvalidOid;
    index->oldNode = InvalidOid;
    index->oldCreateSubid = InvalidSubTransactionId;
    index->oldFirstRelfilenodeSubid = InvalidSubTransactionId;
    index->unique = idxrec->indisunique;
    index->primary = idxrec->indisprimary;
    index->transformed = true;  /* don't need transformIndexStmt */
    index->concurrent = false;
    index->if_not_exists = false;
    index->reset_default_tblspc = false;

    /*
     * We don't try to preserve the name of the source index; instead, just
     * let DefineIndex() choose a reasonable name.  (If we tried to preserve
     * the name, we'd get duplicate-relation-name failures unless the source
     * table was in a different schema.)
     */
    index->idxname = NULL;

    /*
     * If the index is marked PRIMARY or has an exclusion condition, it's
     * certainly from a constraint; else, if it's not marked UNIQUE, it
     * certainly isn't.  If it is or might be from a constraint, we have to
     * fetch the pg_constraint record.
     */
    if (index->primary || index->unique || idxrec->indisexclusion)
    {
        Oid         constraintId = get_index_constraint(source_relid);

        if (OidIsValid(constraintId))
        {
            HeapTuple   ht_constr;
            Form_pg_constraint conrec;

            if (constraintOid)
                *constraintOid = constraintId;

            ht_constr = SearchSysCache1(CONSTROID,
                                        ObjectIdGetDatum(constraintId));
            if (!HeapTupleIsValid(ht_constr))
                elog(ERROR, "cache lookup failed for constraint %u",
                     constraintId);
            conrec = (Form_pg_constraint) GETSTRUCT(ht_constr);

            index->isconstraint = true;
            index->deferrable = conrec->condeferrable;
            index->initdeferred = conrec->condeferred;

            /* If it's an exclusion constraint, we need the operator names */
            if (idxrec->indisexclusion)
            {
                Datum      *elems;
                int         nElems;
                int         i;

                Assert(conrec->contype == CONSTRAINT_EXCLUSION);
                /* Extract operator OIDs from the pg_constraint tuple */
                datum = SysCacheGetAttr(CONSTROID, ht_constr,
                                        Anum_pg_constraint_conexclop,
                                        &isnull);
                if (isnull)
                    elog(ERROR, "null conexclop for constraint %u",
                         constraintId);

                deconstruct_array(DatumGetArrayTypeP(datum),
                                  OIDOID, sizeof(Oid), true, TYPALIGN_INT,
                                  &elems, NULL, &nElems);

                for (i = 0; i < nElems; i++)
                {
                    Oid         operid = DatumGetObjectId(elems[i]);
                    HeapTuple   opertup;
                    Form_pg_operator operform;
                    char       *oprname;
                    char       *nspname;
                    List       *namelist;

                    opertup = SearchSysCache1(OPEROID,
                                              ObjectIdGetDatum(operid));
                    if (!HeapTupleIsValid(opertup))
                        elog(ERROR, "cache lookup failed for operator %u",
                             operid);
                    operform = (Form_pg_operator) GETSTRUCT(opertup);
                    oprname = pstrdup(NameStr(operform->oprname));
                    /* For simplicity we always schema-qualify the op name */
                    nspname = get_namespace_name(operform->oprnamespace);
                    namelist = list_make2(makeString(nspname),
                                          makeString(oprname));
                    index->excludeOpNames = lappend(index->excludeOpNames,
                                                    namelist);
                    ReleaseSysCache(opertup);
                }
            }

            ReleaseSysCache(ht_constr);
        }
        else
            index->isconstraint = false;
    }
    else
        index->isconstraint = false;

    /* Get the index expressions, if any */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indexprs, &isnull);
    if (!isnull)
    {
        char       *exprsString;

        exprsString = TextDatumGetCString(datum);
        indexprs = (List *) stringToNode(exprsString);
    }
    else
        indexprs = NIL;

    /* Build the list of IndexElem */
    index->indexParams = NIL;
    index->indexIncludingParams = NIL;

    indexpr_item = list_head(indexprs);
    for (keyno = 0; keyno < idxrec->indnkeyatts; keyno++)
    {
        IndexElem  *iparam;
        AttrNumber  attnum = idxrec->indkey.values[keyno];
        Form_pg_attribute attr = TupleDescAttr(RelationGetDescr(source_idx),
                                               keyno);
        int16       opt = source_idx->rd_indoption[keyno];

        iparam = makeNode(IndexElem);

        if (AttributeNumberIsValid(attnum))
        {
            /* Simple index column */
            char       *attname;

            attname = get_attname(indrelid, attnum, false);
            keycoltype = get_atttype(indrelid, attnum);

            iparam->name = attname;
            iparam->expr = NULL;
        }
        else
        {
            /* Expressional index */
            Node       *indexkey;
            bool        found_whole_row;

            if (indexpr_item == NULL)
                elog(ERROR, "too few entries in indexprs list");
            indexkey = (Node *) lfirst(indexpr_item);
            indexpr_item = lnext(indexprs, indexpr_item);

            /* Adjust Vars to match new table's column numbering */
            indexkey = map_variable_attnos(indexkey,
                                           1, 0,
                                           attmap,
                                           InvalidOid, &found_whole_row);

            /* As in expandTableLikeClause, reject whole-row variables */
            if (found_whole_row)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot convert whole-row table reference"),
                         errdetail("Index \"%s\" contains a whole-row table reference.",
                                   RelationGetRelationName(source_idx))));

            iparam->name = NULL;
            iparam->expr = indexkey;

            keycoltype = exprType(indexkey);
        }

        /* Copy the original index column name */
        iparam->indexcolname = pstrdup(NameStr(attr->attname));

        /* Add the collation name, if non-default */
        iparam->collation = get_collation(indcollation->values[keyno], keycoltype);

        /* Add the operator class name, if non-default */
        iparam->opclass = get_opclass(indclass->values[keyno], keycoltype);
        iparam->opclassopts =
            untransformRelOptions(get_attoptions(source_relid, keyno + 1));

        iparam->ordering = SORTBY_DEFAULT;
        iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;

        /* Adjust options if necessary */
        if (source_idx->rd_indam->amcanorder)
        {
            /*
             * If it supports sort ordering, copy DESC and NULLS opts. Don't
             * set non-default settings unnecessarily, though, so as to
             * improve the chance of recognizing equivalence to constraint
             * indexes.
             */
            if (opt & INDOPTION_DESC)
            {
                iparam->ordering = SORTBY_DESC;
                if ((opt & INDOPTION_NULLS_FIRST) == 0)
                    iparam->nulls_ordering = SORTBY_NULLS_LAST;
            }
            else
            {
                if (opt & INDOPTION_NULLS_FIRST)
                    iparam->nulls_ordering = SORTBY_NULLS_FIRST;
            }
        }

        index->indexParams = lappend(index->indexParams, iparam);
    }

    /* Handle included columns separately */
    for (keyno = idxrec->indnkeyatts; keyno < idxrec->indnatts; keyno++)
    {
        IndexElem  *iparam;
        AttrNumber  attnum = idxrec->indkey.values[keyno];
        Form_pg_attribute attr = TupleDescAttr(RelationGetDescr(source_idx),
                                               keyno);

        iparam = makeNode(IndexElem);

        if (AttributeNumberIsValid(attnum))
        {
            /* Simple index column */
            char       *attname;

            attname = get_attname(indrelid, attnum, false);

            iparam->name = attname;
            iparam->expr = NULL;
        }
        else
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("expressions are not supported in included columns")));

        /* Copy the original index column name */
        iparam->indexcolname = pstrdup(NameStr(attr->attname));

        index->indexIncludingParams = lappend(index->indexIncludingParams, iparam);
    }
    /* Copy reloptions if any */
    datum = SysCacheGetAttr(RELOID, ht_idxrel,
                            Anum_pg_class_reloptions, &isnull);
    if (!isnull)
        index->options = untransformRelOptions(datum);

    /* If it's a partial index, decompile and append the predicate */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indpred, &isnull);
    if (!isnull)
    {
        char       *pred_str;
        Node       *pred_tree;
        bool        found_whole_row;

        /* Convert text string to node tree */
        pred_str = TextDatumGetCString(datum);
        pred_tree = (Node *) stringToNode(pred_str);

        /* Adjust Vars to match new table's column numbering */
        pred_tree = map_variable_attnos(pred_tree,
                                        1, 0,
                                        attmap,
                                        InvalidOid, &found_whole_row);

        /* As in expandTableLikeClause, reject whole-row variables */
        if (found_whole_row)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot convert whole-row table reference"),
                     errdetail("Index \"%s\" contains a whole-row table reference.",
                               RelationGetRelationName(source_idx))));

        index->whereClause = pred_tree;
    }

    /* Clean up */
    ReleaseSysCache(ht_idxrel);
    ReleaseSysCache(ht_am);

    return index;
}

/*
 * Generate a CreateStatsStmt node using information from an already existing
 * extended statistic "source_statsid", for the rel identified by heapRel and
 * heapRelid.
 */
static CreateStatsStmt *
generateClonedExtStatsStmt(RangeVar *heapRel, Oid heapRelid,
                           Oid source_statsid)
{
    HeapTuple   ht_stats;
    Form_pg_statistic_ext statsrec;
    CreateStatsStmt *stats;
    List       *stat_types = NIL;
    List       *def_names = NIL;
    bool        isnull;
    Datum       datum;
    ArrayType  *arr;
    char       *enabled;
    int         i;

    Assert(OidIsValid(heapRelid));
    Assert(heapRel != NULL);

    /*
     * Fetch pg_statistic_ext tuple of source statistics object.
     */
    ht_stats = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(source_statsid));
    if (!HeapTupleIsValid(ht_stats))
        elog(ERROR, "cache lookup failed for statistics object %u", source_statsid);
    statsrec = (Form_pg_statistic_ext) GETSTRUCT(ht_stats);

    /* Determine which statistics types exist */
    datum = SysCacheGetAttr(STATEXTOID, ht_stats,
                            Anum_pg_statistic_ext_stxkind, &isnull);
    Assert(!isnull);
    arr = DatumGetArrayTypeP(datum);
    if (ARR_NDIM(arr) != 1 ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != CHAROID)
        elog(ERROR, "stxkind is not a 1-D char array");
    enabled = (char *) ARR_DATA_PTR(arr);
    for (i = 0; i < ARR_DIMS(arr)[0]; i++)
    {
        if (enabled[i] == STATS_EXT_NDISTINCT)
            stat_types = lappend(stat_types, makeString("ndistinct"));
        else if (enabled[i] == STATS_EXT_DEPENDENCIES)
            stat_types = lappend(stat_types, makeString("dependencies"));
        else if (enabled[i] == STATS_EXT_MCV)
            stat_types = lappend(stat_types, makeString("mcv"));
        else if (enabled[i] == STATS_EXT_EXPRESSIONS)
            /* expression stats are not exposed to users */
            continue;
        else
            elog(ERROR, "unrecognized statistics kind %c", enabled[i]);
    }

    /* Determine which columns the statistics are on */
    for (i = 0; i < statsrec->stxkeys.dim1; i++)
    {
        StatsElem  *selem = makeNode(StatsElem);
        AttrNumber  attnum = statsrec->stxkeys.values[i];

        selem->name = get_attname(heapRelid, attnum, false);
        selem->expr = NULL;

        def_names = lappend(def_names, selem);
    }

    /*
     * Now handle expressions, if there are any. The order (with respect to
     * regular attributes) does not really matter for extended stats, so we
     * simply append them after simple column references.
     *
     * XXX Some places during build/estimation treat expressions as if they
     * are before attributes, but for the CREATE command that's entirely
     * irrelevant.
     */
    datum = SysCacheGetAttr(STATEXTOID, ht_stats,
                            Anum_pg_statistic_ext_stxexprs, &isnull);

    if (!isnull)
    {
        ListCell   *lc;
        List       *exprs = NIL;
        char       *exprsString;

        exprsString = TextDatumGetCString(datum);
        exprs = (List *) stringToNode(exprsString);

        foreach(lc, exprs)
        {
            StatsElem  *selem = makeNode(StatsElem);

            selem->name = NULL;
            selem->expr = (Node *) lfirst(lc);

            def_names = lappend(def_names, selem);
        }

        pfree(exprsString);
    }

    /* finally, build the output node */
    stats = makeNode(CreateStatsStmt);
    stats->defnames = NULL;
    stats->stat_types = stat_types;
    stats->exprs = def_names;
    stats->relations = list_make1(heapRel);
    stats->stxcomment = NULL;
    stats->transformed = true;  /* don't need transformStatsStmt again */
    stats->if_not_exists = false;

    /* Clean up */
    ReleaseSysCache(ht_stats);

    return stats;
}

/*
 * get_collation        - fetch qualified name of a collation
 *
 * If collation is InvalidOid or is the default for the given actual_datatype,
 * then the return value is NIL.
 */
static List *
get_collation(Oid collation, Oid actual_datatype)
{
    List       *result;
    HeapTuple   ht_coll;
    Form_pg_collation coll_rec;
    char       *nsp_name;
    char       *coll_name;

    if (!OidIsValid(collation))
        return NIL;             /* easy case */
    if (collation == get_typcollation(actual_datatype))
        return NIL;             /* just let it default */

    ht_coll = SearchSysCache1(COLLOID, ObjectIdGetDatum(collation));
    if (!HeapTupleIsValid(ht_coll))
        elog(ERROR, "cache lookup failed for collation %u", collation);
    coll_rec = (Form_pg_collation) GETSTRUCT(ht_coll);

    /* For simplicity, we always schema-qualify the name */
    nsp_name = get_namespace_name(coll_rec->collnamespace);
    coll_name = pstrdup(NameStr(coll_rec->collname));
    result = list_make2(makeString(nsp_name), makeString(coll_name));

    ReleaseSysCache(ht_coll);
    return result;
}

/*
 * get_opclass          - fetch qualified name of an index operator class
 *
 * If the opclass is the default for the given actual_datatype, then
 * the return value is NIL.
 */
static List *
get_opclass(Oid opclass, Oid actual_datatype)
{
    List       *result = NIL;
    HeapTuple   ht_opc;
    Form_pg_opclass opc_rec;

    ht_opc = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclass));
    if (!HeapTupleIsValid(ht_opc))
        elog(ERROR, "cache lookup failed for opclass %u", opclass);
    opc_rec = (Form_pg_opclass) GETSTRUCT(ht_opc);

    if (GetDefaultOpClass(actual_datatype, opc_rec->opcmethod) != opclass)
    {
        /* For simplicity, we always schema-qualify the name */
        char       *nsp_name = get_namespace_name(opc_rec->opcnamespace);
        char       *opc_name = pstrdup(NameStr(opc_rec->opcname));

        result = list_make2(makeString(nsp_name), makeString(opc_name));
    }

    ReleaseSysCache(ht_opc);
    return result;
}


/*
 * transformIndexConstraints
 *      Handle UNIQUE, PRIMARY KEY, EXCLUDE constraints, which create indexes.
 *      We also merge in any index definitions arising from
 *      LIKE ... INCLUDING INDEXES.
 */
static void
transformIndexConstraints(CreateStmtContext *cxt)
{
    IndexStmt  *index;
    List       *indexlist = NIL;
    List       *finalindexlist = NIL;
    ListCell   *lc;

    /*
     * Run through the constraints that need to generate an index. For PRIMARY
     * KEY, mark each column as NOT NULL and create an index. For UNIQUE or
     * EXCLUDE, create an index as for PRIMARY KEY, but do not insist on NOT
     * NULL.
     */
    foreach(lc, cxt->ixconstraints)
    {
        Constraint *constraint = lfirst_node(Constraint, lc);

        Assert(constraint->contype == CONSTR_PRIMARY ||
               constraint->contype == CONSTR_UNIQUE ||
               constraint->contype == CONSTR_EXCLUSION);

        index = transformIndexConstraint(constraint, cxt);

        indexlist = lappend(indexlist, index);
    }

    /*
     * Scan the index list and remove any redundant index specifications. This
     * can happen if, for instance, the user writes UNIQUE PRIMARY KEY. A
     * strict reading of SQL would suggest raising an error instead, but that
     * strikes me as too anal-retentive. - tgl 2001-02-14
     *
     * XXX in ALTER TABLE case, it'd be nice to look for duplicate
     * pre-existing indexes, too.
     */
    if (cxt->pkey != NULL)
    {
        /* Make sure we keep the PKEY index in preference to others... */
        finalindexlist = list_make1(cxt->pkey);
    }

    foreach(lc, indexlist)
    {
        bool        keep = true;
        ListCell   *k;

        index = lfirst(lc);

        /* if it's pkey, it's already in finalindexlist */
        if (index == cxt->pkey)
            continue;

        foreach(k, finalindexlist)
        {
            IndexStmt  *priorindex = lfirst(k);

            if (equal(index->indexParams, priorindex->indexParams) &&
                equal(index->indexIncludingParams, priorindex->indexIncludingParams) &&
                equal(index->whereClause, priorindex->whereClause) &&
                equal(index->excludeOpNames, priorindex->excludeOpNames) &&
                strcmp(index->accessMethod, priorindex->accessMethod) == 0 &&
                index->deferrable == priorindex->deferrable &&
                index->initdeferred == priorindex->initdeferred)
            {
                priorindex->unique |= index->unique;

                /*
                 * If the prior index is as yet unnamed, and this one is
                 * named, then transfer the name to the prior index. This
                 * ensures that if we have named and unnamed constraints,
                 * we'll use (at least one of) the names for the index.
                 */
                if (priorindex->idxname == NULL)
                    priorindex->idxname = index->idxname;
                keep = false;
                break;
            }
        }

        if (keep)
            finalindexlist = lappend(finalindexlist, index);
    }

    /*
     * Now append all the IndexStmts to cxt->alist.  If we generated an ALTER
     * TABLE SET NOT NULL statement to support a primary key, it's already in
     * cxt->alist.
     */
    cxt->alist = list_concat(cxt->alist, finalindexlist);
}

/*
 * transformIndexConstraint
 *      Transform one UNIQUE, PRIMARY KEY, or EXCLUDE constraint for
 *      transformIndexConstraints.
 *
 * We return an IndexStmt.  For a PRIMARY KEY constraint, we additionally
 * produce NOT NULL constraints, either by marking ColumnDefs in cxt->columns
 * as is_not_null or by adding an ALTER TABLE SET NOT NULL command to
 * cxt->alist.
 */
static IndexStmt *
transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
{
    IndexStmt  *index;
    List       *notnullcmds = NIL;
    ListCell   *lc;

    index = makeNode(IndexStmt);

    index->unique = (constraint->contype != CONSTR_EXCLUSION);
    index->primary = (constraint->contype == CONSTR_PRIMARY);
    if (index->primary)
    {
        if (cxt->pkey != NULL)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("multiple primary keys for table \"%s\" are not allowed",
                            cxt->relation->relname),
                     parser_errposition(cxt->pstate, constraint->location)));
        cxt->pkey = index;

        /*
         * In ALTER TABLE case, a primary index might already exist, but
         * DefineIndex will check for it.
         */
    }
    index->isconstraint = true;
    index->deferrable = constraint->deferrable;
    index->initdeferred = constraint->initdeferred;

    if (constraint->conname != NULL)
        index->idxname = pstrdup(constraint->conname);
    else
        index->idxname = NULL;  /* DefineIndex will choose name */

    index->relation = cxt->relation;
    index->accessMethod = constraint->access_method ? constraint->access_method : DEFAULT_INDEX_TYPE;
    index->options = constraint->options;
    index->tableSpace = constraint->indexspace;
    index->whereClause = constraint->where_clause;
    index->indexParams = NIL;
    index->indexIncludingParams = NIL;
    index->excludeOpNames = NIL;
    index->idxcomment = NULL;
    index->indexOid = InvalidOid;
    index->oldNode = InvalidOid;
    index->oldCreateSubid = InvalidSubTransactionId;
    index->oldFirstRelfilenodeSubid = InvalidSubTransactionId;
    index->transformed = false;
    index->concurrent = false;
    index->if_not_exists = false;
    index->reset_default_tblspc = constraint->reset_default_tblspc;

    /*
     * If it's ALTER TABLE ADD CONSTRAINT USING INDEX, look up the index and
     * verify it's usable, then extract the implied column name list.  (We
     * will not actually need the column name list at runtime, but we need it
     * now to check for duplicate column entries below.)
     */
    if (constraint->indexname != NULL)
    {
        char       *index_name = constraint->indexname;
        Relation    heap_rel = cxt->rel;
        Oid         index_oid;
        Relation    index_rel;
        Form_pg_index index_form;
        oidvector  *indclass;
        Datum       indclassDatum;
        bool        isnull;
        int         i;

        /* Grammar should not allow this with explicit column list */
        Assert(constraint->keys == NIL);

        /* Grammar should only allow PRIMARY and UNIQUE constraints */
        Assert(constraint->contype == CONSTR_PRIMARY ||
               constraint->contype == CONSTR_UNIQUE);

        /* Must be ALTER, not CREATE, but grammar doesn't enforce that */
        if (!cxt->isalter)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot use an existing index in CREATE TABLE"),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Look for the index in the same schema as the table */
        index_oid = get_relname_relid(index_name, RelationGetNamespace(heap_rel));

        if (!OidIsValid(index_oid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("index \"%s\" does not exist", index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Open the index (this will throw an error if it is not an index) */
        index_rel = index_open(index_oid, AccessShareLock);
        index_form = index_rel->rd_index;

        /* Check that it does not have an associated constraint already */
        if (OidIsValid(get_index_constraint(index_oid)))
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("index \"%s\" is already associated with a constraint",
                            index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Perform validity checks on the index */
        if (index_form->indrelid != RelationGetRelid(heap_rel))
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("index \"%s\" does not belong to table \"%s\"",
                            index_name, RelationGetRelationName(heap_rel)),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (!index_form->indisvalid)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("index \"%s\" is not valid", index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (!index_form->indisunique)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("\"%s\" is not a unique index", index_name),
                     errdetail("Cannot create a primary key or unique constraint using such an index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (RelationGetIndexExpressions(index_rel) != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("index \"%s\" contains expressions", index_name),
                     errdetail("Cannot create a primary key or unique constraint using such an index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (RelationGetIndexPredicate(index_rel) != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("\"%s\" is a partial index", index_name),
                     errdetail("Cannot create a primary key or unique constraint using such an index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        /*
         * It's probably unsafe to change a deferred index to non-deferred. (A
         * non-constraint index couldn't be deferred anyway, so this case
         * should never occur; no need to sweat, but let's check it.)
         */
        if (!index_form->indimmediate && !constraint->deferrable)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("\"%s\" is a deferrable index", index_name),
                     errdetail("Cannot create a non-deferrable constraint using a deferrable index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        /*
         * Insist on it being a btree.  That's the only kind that supports
         * uniqueness at the moment anyway; but we must have an index that
         * exactly matches what you'd get from plain ADD CONSTRAINT syntax,
         * else dump and reload will produce a different index (breaking
         * pg_upgrade in particular).
         */
        if (index_rel->rd_rel->relam != get_index_am_oid(DEFAULT_INDEX_TYPE, false))
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("index \"%s\" is not a btree", index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Must get indclass the hard way */
        indclassDatum = SysCacheGetAttr(INDEXRELID, index_rel->rd_indextuple,
                                        Anum_pg_index_indclass, &isnull);
        Assert(!isnull);
        indclass = (oidvector *) DatumGetPointer(indclassDatum);

        for (i = 0; i < index_form->indnatts; i++)
        {
            int16       attnum = index_form->indkey.values[i];
            const FormData_pg_attribute *attform;
            char       *attname;
            Oid         defopclass;

            /*
             * We shouldn't see attnum == 0 here, since we already rejected
             * expression indexes.  If we do, SystemAttributeDefinition will
             * throw an error.
             */
            if (attnum > 0)
            {
                Assert(attnum <= heap_rel->rd_att->natts);
                attform = TupleDescAttr(heap_rel->rd_att, attnum - 1);
            }
            else
                attform = SystemAttributeDefinition(attnum);
            attname = pstrdup(NameStr(attform->attname));

            if (i < index_form->indnkeyatts)
            {
                /*
                 * Insist on default opclass, collation, and sort options.
                 * While the index would still work as a constraint with
                 * non-default settings, it might not provide exactly the same
                 * uniqueness semantics as you'd get from a normally-created
                 * constraint; and there's also the dump/reload problem
                 * mentioned above.
                 */
                Datum       attoptions =
                get_attoptions(RelationGetRelid(index_rel), i + 1);

                defopclass = GetDefaultOpClass(attform->atttypid,
                                               index_rel->rd_rel->relam);
                if (indclass->values[i] != defopclass ||
                    attform->attcollation != index_rel->rd_indcollation[i] ||
                    attoptions != (Datum) 0 ||
                    index_rel->rd_indoption[i] != 0)
                    ereport(ERROR,
                            (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                             errmsg("index \"%s\" column number %d does not have default sorting behavior", index_name, i + 1),
                             errdetail("Cannot create a primary key or unique constraint using such an index."),
                             parser_errposition(cxt->pstate, constraint->location)));

                constraint->keys = lappend(constraint->keys, makeString(attname));
            }
            else
                constraint->including = lappend(constraint->including, makeString(attname));
        }

        /* Close the index relation but keep the lock */
        relation_close(index_rel, NoLock);

        index->indexOid = index_oid;
    }

    /*
     * If it's an EXCLUDE constraint, the grammar returns a list of pairs of
     * IndexElems and operator names.  We have to break that apart into
     * separate lists.
     */
    if (constraint->contype == CONSTR_EXCLUSION)
    {
        foreach(lc, constraint->exclusions)
        {
            List       *pair = (List *) lfirst(lc);
            IndexElem  *elem;
            List       *opname;

            Assert(list_length(pair) == 2);
            elem = linitial_node(IndexElem, pair);
            opname = lsecond_node(List, pair);

            index->indexParams = lappend(index->indexParams, elem);
            index->excludeOpNames = lappend(index->excludeOpNames, opname);
        }
    }

    /*
     * For UNIQUE and PRIMARY KEY, we just have a list of column names.
     *
     * Make sure referenced keys exist.  If we are making a PRIMARY KEY index,
     * also make sure they are NOT NULL.
     */
    else
    {
        foreach(lc, constraint->keys)
        {
            char       *key = strVal(lfirst(lc));
            bool        found = false;
            bool        forced_not_null = false;
            ColumnDef  *column = NULL;
            ListCell   *columns;
            IndexElem  *iparam;

            /* Make sure referenced column exists. */
            foreach(columns, cxt->columns)
            {
                column = castNode(ColumnDef, lfirst(columns));
                if (strcmp(column->colname, key) == 0)
                {
                    found = true;
                    break;
                }
            }
            if (found)
            {
                /*
                 * column is defined in the new table.  For PRIMARY KEY, we
                 * can apply the NOT NULL constraint cheaply here ... unless
                 * the column is marked is_from_type, in which case marking it
                 * here would be ineffective (see MergeAttributes).
                 */
                if (constraint->contype == CONSTR_PRIMARY &&
                    !column->is_from_type)
                {
                    column->is_not_null = true;
                    forced_not_null = true;
                }
            }
            else if (SystemAttributeByName(key) != NULL)
            {
                /*
                 * column will be a system column in the new table, so accept
                 * it. System columns can't ever be null, so no need to worry
                 * about PRIMARY/NOT NULL constraint.
                 */
                found = true;
            }
            else if (cxt->inhRelations)
            {
                /* try inherited tables */
                ListCell   *inher;

                foreach(inher, cxt->inhRelations)
                {
                    RangeVar   *inh = castNode(RangeVar, lfirst(inher));
                    Relation    rel;
                    int         count;

                    rel = table_openrv(inh, AccessShareLock);
                    /* check user requested inheritance from valid relkind */
                    if (rel->rd_rel->relkind != RELKIND_RELATION &&
                        rel->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
                        rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
                        ereport(ERROR,
                                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                 errmsg("inherited relation \"%s\" is not a table or foreign table",
                                        inh->relname)));
                    for (count = 0; count < rel->rd_att->natts; count++)
                    {
                        Form_pg_attribute inhattr = TupleDescAttr(rel->rd_att,
                                                                  count);
                        char       *inhname = NameStr(inhattr->attname);

                        if (inhattr->attisdropped)
                            continue;
                        if (strcmp(key, inhname) == 0)
                        {
                            found = true;

                            /*
                             * It's tempting to set forced_not_null if the
                             * parent column is already NOT NULL, but that
                             * seems unsafe because the column's NOT NULL
                             * marking might disappear between now and
                             * execution.  Do the runtime check to be safe.
                             */
                            break;
                        }
                    }
                    table_close(rel, NoLock);
                    if (found)
                        break;
                }
            }

            /*
             * In the ALTER TABLE case, don't complain about index keys not
             * created in the command; they may well exist already.
             * DefineIndex will complain about them if not.
             */
            if (!found && !cxt->isalter)
                ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" named in key does not exist", key),
                         parser_errposition(cxt->pstate, constraint->location)));

            /* Check for PRIMARY KEY(foo, foo) */
            foreach(columns, index->indexParams)
            {
                iparam = (IndexElem *) lfirst(columns);
                if (iparam->name && strcmp(key, iparam->name) == 0)
                {
                    if (index->primary)
                        ereport(ERROR,
                                (errcode(ERRCODE_DUPLICATE_COLUMN),
                                 errmsg("column \"%s\" appears twice in primary key constraint",
                                        key),
                                 parser_errposition(cxt->pstate, constraint->location)));
                    else
                        ereport(ERROR,
                                (errcode(ERRCODE_DUPLICATE_COLUMN),
                                 errmsg("column \"%s\" appears twice in unique constraint",
                                        key),
                                 parser_errposition(cxt->pstate, constraint->location)));
                }
            }

            /* OK, add it to the index definition */
            iparam = makeNode(IndexElem);
            iparam->name = pstrdup(key);
            iparam->expr = NULL;
            iparam->indexcolname = NULL;
            iparam->collation = NIL;
            iparam->opclass = NIL;
            iparam->opclassopts = NIL;
            iparam->ordering = SORTBY_DEFAULT;
            iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;
            index->indexParams = lappend(index->indexParams, iparam);

            /*
             * For a primary-key column, also create an item for ALTER TABLE
             * SET NOT NULL if we couldn't ensure it via is_not_null above.
             */
            if (constraint->contype == CONSTR_PRIMARY && !forced_not_null)
            {
                AlterTableCmd *notnullcmd = makeNode(AlterTableCmd);

                notnullcmd->subtype = AT_SetNotNull;
                notnullcmd->name = pstrdup(key);
                notnullcmds = lappend(notnullcmds, notnullcmd);
            }
        }
    }

    /*
     * Add included columns to index definition.  This is much like the
     * simple-column-name-list code above, except that we don't worry about
     * NOT NULL marking; included columns in a primary key should not be
     * forced NOT NULL.  We don't complain about duplicate columns, either,
     * though maybe we should?
     */
    foreach(lc, constraint->including)
    {
        char       *key = strVal(lfirst(lc));
        bool        found = false;
        ColumnDef  *column = NULL;
        ListCell   *columns;
        IndexElem  *iparam;

        foreach(columns, cxt->columns)
        {
            column = lfirst_node(ColumnDef, columns);
            if (strcmp(column->colname, key) == 0)
            {
                found = true;
                break;
            }
        }

        if (!found)
        {
            if (SystemAttributeByName(key) != NULL)
            {
                /*
                 * column will be a system column in the new table, so accept
                 * it.
                 */
                found = true;
            }
            else if (cxt->inhRelations)
            {
                /* try inherited tables */
                ListCell   *inher;

                foreach(inher, cxt->inhRelations)
                {
                    RangeVar   *inh = lfirst_node(RangeVar, inher);
                    Relation    rel;
                    int         count;

                    rel = table_openrv(inh, AccessShareLock);
                    /* check user requested inheritance from valid relkind */
                    if (rel->rd_rel->relkind != RELKIND_RELATION &&
                        rel->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
                        rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
                        ereport(ERROR,
                                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                 errmsg("inherited relation \"%s\" is not a table or foreign table",
                                        inh->relname)));
                    for (count = 0; count < rel->rd_att->natts; count++)
                    {
                        Form_pg_attribute inhattr = TupleDescAttr(rel->rd_att,
                                                                  count);
                        char       *inhname = NameStr(inhattr->attname);

                        if (inhattr->attisdropped)
                            continue;
                        if (strcmp(key, inhname) == 0)
                        {
                            found = true;
                            break;
                        }
                    }
                    table_close(rel, NoLock);
                    if (found)
                        break;
                }
            }
        }

        /*
         * In the ALTER TABLE case, don't complain about index keys not
         * created in the command; they may well exist already. DefineIndex
         * will complain about them if not.
         */
        if (!found && !cxt->isalter)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" named in key does not exist", key),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* OK, add it to the index definition */
        iparam = makeNode(IndexElem);
        iparam->name = pstrdup(key);
        iparam->expr = NULL;
        iparam->indexcolname = NULL;
        iparam->collation = NIL;
        iparam->opclass = NIL;
        iparam->opclassopts = NIL;
        index->indexIncludingParams = lappend(index->indexIncludingParams, iparam);
    }

    /*
     * If we found anything that requires run-time SET NOT NULL, build a full
     * ALTER TABLE command for that and add it to cxt->alist.
     */
    if (notnullcmds)
    {
        AlterTableStmt *alterstmt = makeNode(AlterTableStmt);

        alterstmt->relation = copyObject(cxt->relation);
        alterstmt->cmds = notnullcmds;
        alterstmt->objtype = OBJECT_TABLE;
        alterstmt->missing_ok = false;

        cxt->alist = lappend(cxt->alist, alterstmt);
    }

    return index;
}

/*
 * transformExtendedStatistics
 *     Handle extended statistic objects
 *
 * Right now, there's nothing to do here, so we just append the list to
 * the existing "after" list.
 */
static void
transformExtendedStatistics(CreateStmtContext *cxt)
{
    cxt->alist = list_concat(cxt->alist, cxt->extstats);
}

/*
 * transformCheckConstraints
 *      handle CHECK constraints
 *
 * Right now, there's nothing to do here when called from ALTER TABLE,
 * but the other constraint-transformation functions are called in both
 * the CREATE TABLE and ALTER TABLE paths, so do the same here, and just
 * don't do anything if we're not authorized to skip validation.
 */
static void
transformCheckConstraints(CreateStmtContext *cxt, bool skipValidation)
{
    ListCell   *ckclist;

    if (cxt->ckconstraints == NIL)
        return;

    /*
     * If creating a new table (but not a foreign table), we can safely skip
     * validation of check constraints, and nonetheless mark them valid. (This
     * will override any user-supplied NOT VALID flag.)
     */
    if (skipValidation)
    {
        foreach(ckclist, cxt->ckconstraints)
        {
            Constraint *constraint = (Constraint *) lfirst(ckclist);

            constraint->skip_validation = true;
            constraint->initially_valid = true;
        }
    }
}

/*
 * transformFKConstraints
 *      handle FOREIGN KEY constraints
 */
static void
transformFKConstraints(CreateStmtContext *cxt,
                       bool skipValidation, bool isAddConstraint)
{
    ListCell   *fkclist;

    if (cxt->fkconstraints == NIL)
        return;

    /*
     * If CREATE TABLE or adding a column with NULL default, we can safely
     * skip validation of FK constraints, and nonetheless mark them valid.
     * (This will override any user-supplied NOT VALID flag.)
     */
    if (skipValidation)
    {
        foreach(fkclist, cxt->fkconstraints)
        {
            Constraint *constraint = (Constraint *) lfirst(fkclist);

            constraint->skip_validation = true;
            constraint->initially_valid = true;
        }
    }

    /*
     * For CREATE TABLE or ALTER TABLE ADD COLUMN, gin up an ALTER TABLE ADD
     * CONSTRAINT command to execute after the basic command is complete. (If
     * called from ADD CONSTRAINT, that routine will add the FK constraints to
     * its own subcommand list.)
     *
     * Note: the ADD CONSTRAINT command must also execute after any index
     * creation commands.  Thus, this should run after
     * transformIndexConstraints, so that the CREATE INDEX commands are
     * already in cxt->alist.  See also the handling of cxt->likeclauses.
     */
    if (!isAddConstraint)
    {
        AlterTableStmt *alterstmt = makeNode(AlterTableStmt);

        alterstmt->relation = cxt->relation;
        alterstmt->cmds = NIL;
        alterstmt->objtype = OBJECT_TABLE;

        foreach(fkclist, cxt->fkconstraints)
        {
            Constraint *constraint = (Constraint *) lfirst(fkclist);
            AlterTableCmd *altercmd = makeNode(AlterTableCmd);

            altercmd->subtype = AT_AddConstraint;
            altercmd->name = NULL;
            altercmd->def = (Node *) constraint;
            alterstmt->cmds = lappend(alterstmt->cmds, altercmd);
        }

        cxt->alist = lappend(cxt->alist, alterstmt);
    }
}

/*
 * transformIndexStmt - parse analysis for CREATE INDEX and ALTER TABLE
 *
 * Note: this is a no-op for an index not using either index expressions or
 * a predicate expression.  There are several code paths that create indexes
 * without bothering to call this, because they know they don't have any
 * such expressions to deal with.
 *
 * To avoid race conditions, it's important that this function rely only on
 * the passed-in relid (and not on stmt->relation) to determine the target
 * relation.
 */
IndexStmt *
transformIndexStmt(Oid relid, IndexStmt *stmt, const char *queryString)
{
    ParseState *pstate;
    ParseNamespaceItem *nsitem;
    ListCell   *l;
    Relation    rel;

    /* Nothing to do if statement already transformed. */
    if (stmt->transformed)
        return stmt;

    /* Set up pstate */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /*
     * Put the parent table into the rtable so that the expressions can refer
     * to its fields without qualification.  Caller is responsible for locking
     * relation, but we still need to open it.
     */
    rel = relation_open(relid, NoLock);
    nsitem = addRangeTableEntryForRelation(pstate, rel,
                                           AccessShareLock,
                                           NULL, false, true);

    /* no to join list, yes to namespaces */
    addNSItemToQuery(pstate, nsitem, false, true, true);

    /* take care of the where clause */
    if (stmt->whereClause)
    {
        stmt->whereClause = transformWhereClause(pstate,
                                                 stmt->whereClause,
                                                 EXPR_KIND_INDEX_PREDICATE,
                                                 "WHERE");
        /* we have to fix its collations too */
        assign_expr_collations(pstate, stmt->whereClause);
    }

    /* take care of any index expressions */
    foreach(l, stmt->indexParams)
    {
        IndexElem  *ielem = (IndexElem *) lfirst(l);

        if (ielem->expr)
        {
            /* Extract preliminary index col name before transforming expr */
            if (ielem->indexcolname == NULL)
                ielem->indexcolname = FigureIndexColname(ielem->expr);

            /* Now do parse transformation of the expression */
            ielem->expr = transformExpr(pstate, ielem->expr,
                                        EXPR_KIND_INDEX_EXPRESSION);

            /* We have to fix its collations too */
            assign_expr_collations(pstate, ielem->expr);

            /*
             * transformExpr() should have already rejected subqueries,
             * aggregates, window functions, and SRFs, based on the EXPR_KIND_
             * for an index expression.
             *
             * DefineIndex() will make more checks.
             */
        }
    }

    /*
     * Check that only the base rel is mentioned.  (This should be dead code
     * now that add_missing_from is history.)
     */
    if (list_length(pstate->p_rtable) != 1)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
                 errmsg("index expressions and predicates can refer only to the table being indexed")));

    free_parsestate(pstate);

    /* Close relation */
    table_close(rel, NoLock);

    /* Mark statement as successfully transformed */
    stmt->transformed = true;

    return stmt;
}

/*
 * transformStatsStmt - parse analysis for CREATE STATISTICS
 *
 * To avoid race conditions, it's important that this function rely only on
 * the passed-in relid (and not on stmt->relation) to determine the target
 * relation.
 */
CreateStatsStmt *
transformStatsStmt(Oid relid, CreateStatsStmt *stmt, const char *queryString)
{
    ParseState *pstate;
    ParseNamespaceItem *nsitem;
    ListCell   *l;
    Relation    rel;

    /* Nothing to do if statement already transformed. */
    if (stmt->transformed)
        return stmt;

    /* Set up pstate */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /*
     * Put the parent table into the rtable so that the expressions can refer
     * to its fields without qualification.  Caller is responsible for locking
     * relation, but we still need to open it.
     */
    rel = relation_open(relid, NoLock);
    nsitem = addRangeTableEntryForRelation(pstate, rel,
                                           AccessShareLock,
                                           NULL, false, true);

    /* no to join list, yes to namespaces */
    addNSItemToQuery(pstate, nsitem, false, true, true);

    /* take care of any expressions */
    foreach(l, stmt->exprs)
    {
        StatsElem  *selem = (StatsElem *) lfirst(l);

        if (selem->expr)
        {
            /* Now do parse transformation of the expression */
            selem->expr = transformExpr(pstate, selem->expr,
                                        EXPR_KIND_STATS_EXPRESSION);

            /* We have to fix its collations too */
            assign_expr_collations(pstate, selem->expr);
        }
    }

    /*
     * Check that only the base rel is mentioned.  (This should be dead code
     * now that add_missing_from is history.)
     */
    if (list_length(pstate->p_rtable) != 1)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
                 errmsg("statistics expressions can refer only to the table being indexed")));

    free_parsestate(pstate);

    /* Close relation */
    table_close(rel, NoLock);

    /* Mark statement as successfully transformed */
    stmt->transformed = true;

    return stmt;
}


/*
 * transformRuleStmt -
 *    transform a CREATE RULE Statement. The action is a list of parse
 *    trees which is transformed into a list of query trees, and we also
 *    transform the WHERE clause if any.
 *
 * actions and whereClause are output parameters that receive the
 * transformed results.
 */
void
transformRuleStmt(RuleStmt *stmt, const char *queryString,
                  List **actions, Node **whereClause)
{
    Relation    rel;
    ParseState *pstate;
    ParseNamespaceItem *oldnsitem;
    ParseNamespaceItem *newnsitem;

    /*
     * To avoid deadlock, make sure the first thing we do is grab
     * AccessExclusiveLock on the target relation.  This will be needed by
     * DefineQueryRewrite(), and we don't want to grab a lesser lock
     * beforehand.
     */
    rel = table_openrv(stmt->relation, AccessExclusiveLock);

    if (rel->rd_rel->relkind == RELKIND_MATVIEW)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("rules on materialized views are not supported")));

    /* Set up pstate */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /*
     * NOTE: 'OLD' must always have a varno equal to 1 and 'NEW' equal to 2.
     * Set up their ParseNamespaceItems in the main pstate for use in parsing
     * the rule qualification.
     */
    oldnsitem = addRangeTableEntryForRelation(pstate, rel,
                                              AccessShareLock,
                                              makeAlias("old", NIL),
                                              false, false);
    newnsitem = addRangeTableEntryForRelation(pstate, rel,
                                              AccessShareLock,
                                              makeAlias("new", NIL),
                                              false, false);
    /* Must override addRangeTableEntry's default access-check flags */
    oldnsitem->p_rte->requiredPerms = 0;
    newnsitem->p_rte->requiredPerms = 0;

    /*
     * They must be in the namespace too for lookup purposes, but only add the
     * one(s) that are relevant for the current kind of rule.  In an UPDATE
     * rule, quals must refer to OLD.field or NEW.field to be unambiguous, but
     * there's no need to be so picky for INSERT & DELETE.  We do not add them
     * to the joinlist.
     */
    switch (stmt->event)
    {
        case CMD_SELECT:
            addNSItemToQuery(pstate, oldnsitem, false, true, true);
            break;
        case CMD_UPDATE:
            addNSItemToQuery(pstate, oldnsitem, false, true, true);
            addNSItemToQuery(pstate, newnsitem, false, true, true);
            break;
        case CMD_INSERT:
            addNSItemToQuery(pstate, newnsitem, false, true, true);
            break;
        case CMD_DELETE:
            addNSItemToQuery(pstate, oldnsitem, false, true, true);
            break;
        default:
            elog(ERROR, "unrecognized event type: %d",
                 (int) stmt->event);
            break;
    }

    /* take care of the where clause */
    *whereClause = transformWhereClause(pstate,
                                        stmt->whereClause,
                                        EXPR_KIND_WHERE,
                                        "WHERE");
    /* we have to fix its collations too */
    assign_expr_collations(pstate, *whereClause);

    /* this is probably dead code without add_missing_from: */
    if (list_length(pstate->p_rtable) != 2) /* naughty, naughty... */
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("rule WHERE condition cannot contain references to other relations")));

    /*
     * 'instead nothing' rules with a qualification need a query rangetable so
     * the rewrite handler can add the negated rule qualification to the
     * original query. We create a query with the new command type CMD_NOTHING
     * here that is treated specially by the rewrite system.
     */
    if (stmt->actions == NIL)
    {
        Query      *nothing_qry = makeNode(Query);

        nothing_qry->commandType = CMD_NOTHING;
        nothing_qry->rtable = pstate->p_rtable;
        nothing_qry->jointree = makeFromExpr(NIL, NULL);    /* no join wanted */

        *actions = list_make1(nothing_qry);
    }
    else
    {
        ListCell   *l;
        List       *newactions = NIL;

        /*
         * transform each statement, like parse_sub_analyze()
         */
        foreach(l, stmt->actions)
        {
            Node       *action = (Node *) lfirst(l);
            ParseState *sub_pstate = make_parsestate(NULL);
            Query      *sub_qry,
                       *top_subqry;
            bool        has_old,
                        has_new;

            /*
             * Since outer ParseState isn't parent of inner, have to pass down
             * the query text by hand.
             */
            sub_pstate->p_sourcetext = queryString;

            /*
             * Set up OLD/NEW in the rtable for this statement.  The entries
             * are added only to relnamespace, not varnamespace, because we
             * don't want them to be referred to by unqualified field names
             * nor "*" in the rule actions.  We decide later whether to put
             * them in the joinlist.
             */
            oldnsitem = addRangeTableEntryForRelation(sub_pstate, rel,
                                                      AccessShareLock,
                                                      makeAlias("old", NIL),
                                                      false, false);
            newnsitem = addRangeTableEntryForRelation(sub_pstate, rel,
                                                      AccessShareLock,
                                                      makeAlias("new", NIL),
                                                      false, false);
            oldnsitem->p_rte->requiredPerms = 0;
            newnsitem->p_rte->requiredPerms = 0;
            addNSItemToQuery(sub_pstate, oldnsitem, false, true, false);
            addNSItemToQuery(sub_pstate, newnsitem, false, true, false);

            /* Transform the rule action statement */
            top_subqry = transformStmt(sub_pstate, action);

            /*
             * We cannot support utility-statement actions (eg NOTIFY) with
             * nonempty rule WHERE conditions, because there's no way to make
             * the utility action execute conditionally.
             */
            if (top_subqry->commandType == CMD_UTILITY &&
                *whereClause != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("rules with WHERE conditions can only have SELECT, INSERT, UPDATE, or DELETE actions")));

            /*
             * If the action is INSERT...SELECT, OLD/NEW have been pushed down
             * into the SELECT, and that's what we need to look at. (Ugly
             * kluge ... try to fix this when we redesign querytrees.)
             */
            sub_qry = getInsertSelectQuery(top_subqry, NULL);

            /*
             * If the sub_qry is a setop, we cannot attach any qualifications
             * to it, because the planner won't notice them.  This could
             * perhaps be relaxed someday, but for now, we may as well reject
             * such a rule immediately.
             */
            if (sub_qry->setOperations != NULL && *whereClause != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));

            /*
             * Validate action's use of OLD/NEW, qual too
             */
            has_old =
                rangeTableEntry_used((Node *) sub_qry, PRS2_OLD_VARNO, 0) ||
                rangeTableEntry_used(*whereClause, PRS2_OLD_VARNO, 0);
            has_new =
                rangeTableEntry_used((Node *) sub_qry, PRS2_NEW_VARNO, 0) ||
                rangeTableEntry_used(*whereClause, PRS2_NEW_VARNO, 0);

            switch (stmt->event)
            {
                case CMD_SELECT:
                    if (has_old)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON SELECT rule cannot use OLD")));
                    if (has_new)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON SELECT rule cannot use NEW")));
                    break;
                case CMD_UPDATE:
                    /* both are OK */
                    break;
                case CMD_INSERT:
                    if (has_old)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON INSERT rule cannot use OLD")));
                    break;
                case CMD_DELETE:
                    if (has_new)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON DELETE rule cannot use NEW")));
                    break;
                default:
                    elog(ERROR, "unrecognized event type: %d",
                         (int) stmt->event);
                    break;
            }

            /*
             * OLD/NEW are not allowed in WITH queries, because they would
             * amount to outer references for the WITH, which we disallow.
             * However, they were already in the outer rangetable when we
             * analyzed the query, so we have to check.
             *
             * Note that in the INSERT...SELECT case, we need to examine the
             * CTE lists of both top_subqry and sub_qry.
             *
             * Note that we aren't digging into the body of the query looking
             * for WITHs in nested sub-SELECTs.  A WITH down there can
             * legitimately refer to OLD/NEW, because it'd be an
             * indirect-correlated outer reference.
             */
            if (rangeTableEntry_used((Node *) top_subqry->cteList,
                                     PRS2_OLD_VARNO, 0) ||
                rangeTableEntry_used((Node *) sub_qry->cteList,
                                     PRS2_OLD_VARNO, 0))
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot refer to OLD within WITH query")));
            if (rangeTableEntry_used((Node *) top_subqry->cteList,
                                     PRS2_NEW_VARNO, 0) ||
                rangeTableEntry_used((Node *) sub_qry->cteList,
                                     PRS2_NEW_VARNO, 0))
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot refer to NEW within WITH query")));

            /*
             * For efficiency's sake, add OLD to the rule action's jointree
             * only if it was actually referenced in the statement or qual.
             *
             * For INSERT, NEW is not really a relation (only a reference to
             * the to-be-inserted tuple) and should never be added to the
             * jointree.
             *
             * For UPDATE, we treat NEW as being another kind of reference to
             * OLD, because it represents references to *transformed* tuples
             * of the existing relation.  It would be wrong to enter NEW
             * separately in the jointree, since that would cause a double
             * join of the updated relation.  It's also wrong to fail to make
             * a jointree entry if only NEW and not OLD is mentioned.
             */
            if (has_old || (has_new && stmt->event == CMD_UPDATE))
            {
                RangeTblRef *rtr;

                /*
                 * If sub_qry is a setop, manipulating its jointree will do no
                 * good at all, because the jointree is dummy. (This should be
                 * a can't-happen case because of prior tests.)
                 */
                if (sub_qry->setOperations != NULL)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
                /* hackishly add OLD to the already-built FROM clause */
                rtr = makeNode(RangeTblRef);
                rtr->rtindex = oldnsitem->p_rtindex;
                sub_qry->jointree->fromlist =
                    lappend(sub_qry->jointree->fromlist, rtr);
            }

            newactions = lappend(newactions, top_subqry);

            free_parsestate(sub_pstate);
        }

        *actions = newactions;
    }

    free_parsestate(pstate);

    /* Close relation, but keep the exclusive lock */
    table_close(rel, NoLock);
}


/*
 * transformAlterTableStmt -
 *      parse analysis for ALTER TABLE
 *
 * Returns the transformed AlterTableStmt.  There may be additional actions
 * to be done before and after the transformed statement, which are returned
 * in *beforeStmts and *afterStmts as lists of utility command parsetrees.
 *
 * To avoid race conditions, it's important that this function rely only on
 * the passed-in relid (and not on stmt->relation) to determine the target
 * relation.
 */
AlterTableStmt *
transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
                        const char *queryString,
                        List **beforeStmts, List **afterStmts)
{
    Relation    rel;
    TupleDesc   tupdesc;
    ParseState *pstate;
    CreateStmtContext cxt;
    List       *save_alist;
    ListCell   *lcmd,
               *l;
    List       *newcmds = NIL;
    bool        skipValidation = true;
    AlterTableCmd *newcmd;
    ParseNamespaceItem *nsitem;

    /* Caller is responsible for locking the relation */
    rel = relation_open(relid, NoLock);
    tupdesc = RelationGetDescr(rel);

    /* Set up pstate */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;
    nsitem = addRangeTableEntryForRelation(pstate,
                                           rel,
                                           AccessShareLock,
                                           NULL,
                                           false,
                                           true);
    addNSItemToQuery(pstate, nsitem, false, true, true);

    /* Set up CreateStmtContext */
    cxt.pstate = pstate;
    if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
    {
        cxt.stmtType = "ALTER FOREIGN TABLE";
        cxt.isforeign = true;
    }
    else
    {
        cxt.stmtType = "ALTER TABLE";
        cxt.isforeign = false;
    }
    cxt.relation = stmt->relation;
    cxt.rel = rel;
    cxt.inhRelations = NIL;
    cxt.isalter = true;
    cxt.columns = NIL;
    cxt.ckconstraints = NIL;
    cxt.fkconstraints = NIL;
    cxt.ixconstraints = NIL;
    cxt.likeclauses = NIL;
    cxt.extstats = NIL;
    cxt.blist = NIL;
    cxt.alist = NIL;
    cxt.pkey = NULL;
    cxt.ispartitioned = (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
    cxt.partbound = NULL;
    cxt.ofType = false;

    /*
     * Transform ALTER subcommands that need it (most don't).  These largely
     * re-use code from CREATE TABLE.
     */
    foreach(lcmd, stmt->cmds)
    {
        AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);

        switch (cmd->subtype)
        {
            case AT_AddColumn:
            case AT_AddColumnRecurse:
                {
                    ColumnDef  *def = castNode(ColumnDef, cmd->def);

                    transformColumnDefinition(&cxt, def);

                    /*
                     * If the column has a non-null default, we can't skip
                     * validation of foreign keys.
                     */
                    if (def->raw_default != NULL)
                        skipValidation = false;

                    /*
                     * All constraints are processed in other ways. Remove the
                     * original list
                     */
                    def->constraints = NIL;

                    newcmds = lappend(newcmds, cmd);
                    break;
                }

            case AT_AddConstraint:
            case AT_AddConstraintRecurse:

                /*
                 * The original AddConstraint cmd node doesn't go to newcmds
                 */
                if (IsA(cmd->def, Constraint))
                {
                    transformTableConstraint(&cxt, (Constraint *) cmd->def);
                    if (((Constraint *) cmd->def)->contype == CONSTR_FOREIGN)
                        skipValidation = false;
                }
                else
                    elog(ERROR, "unrecognized node type: %d",
                         (int) nodeTag(cmd->def));
                break;

            case AT_AlterColumnType:
                {
                    ColumnDef  *def = castNode(ColumnDef, cmd->def);
                    AttrNumber  attnum;

                    /*
                     * For ALTER COLUMN TYPE, transform the USING clause if
                     * one was specified.
                     */
                    if (def->raw_default)
                    {
                        def->cooked_default =
                            transformExpr(pstate, def->raw_default,
                                          EXPR_KIND_ALTER_COL_TRANSFORM);
                    }

                    /*
                     * For identity column, create ALTER SEQUENCE command to
                     * change the data type of the sequence.
                     */
                    attnum = get_attnum(relid, cmd->name);
                    if (attnum == InvalidAttrNumber)
                        ereport(ERROR,
                                (errcode(ERRCODE_UNDEFINED_COLUMN),
                                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                                        cmd->name, RelationGetRelationName(rel))));

                    if (TupleDescAttr(tupdesc, attnum - 1)->attidentity)
                    {
                        Oid         seq_relid = getIdentitySequence(relid, attnum, false);
                        Oid         typeOid = typenameTypeId(pstate, def->typeName);
                        AlterSeqStmt *altseqstmt = makeNode(AlterSeqStmt);

                        altseqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
                                                            get_rel_name(seq_relid),
                                                            -1);
                        altseqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(typeOid, -1), -1));
                        altseqstmt->for_identity = true;
                        cxt.blist = lappend(cxt.blist, altseqstmt);
                    }

                    newcmds = lappend(newcmds, cmd);
                    break;
                }

            case AT_AddIdentity:
                {
                    Constraint *def = castNode(Constraint, cmd->def);
                    ColumnDef  *newdef = makeNode(ColumnDef);
                    AttrNumber  attnum;

                    newdef->colname = cmd->name;
                    newdef->identity = def->generated_when;
                    cmd->def = (Node *) newdef;

                    attnum = get_attnum(relid, cmd->name);
                    if (attnum == InvalidAttrNumber)
                        ereport(ERROR,
                                (errcode(ERRCODE_UNDEFINED_COLUMN),
                                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                                        cmd->name, RelationGetRelationName(rel))));

                    generateSerialExtraStmts(&cxt, newdef,
                                             get_atttype(relid, attnum),
                                             def->options, true, true,
                                             NULL, NULL);

                    newcmds = lappend(newcmds, cmd);
                    break;
                }

            case AT_SetIdentity:
                {
                    /*
                     * Create an ALTER SEQUENCE statement for the internal
                     * sequence of the identity column.
                     */
                    ListCell   *lc;
                    List       *newseqopts = NIL;
                    List       *newdef = NIL;
                    AttrNumber  attnum;
                    Oid         seq_relid;

                    /*
                     * Split options into those handled by ALTER SEQUENCE and
                     * those for ALTER TABLE proper.
                     */
                    foreach(lc, castNode(List, cmd->def))
                    {
                        DefElem    *def = lfirst_node(DefElem, lc);

                        if (strcmp(def->defname, "generated") == 0)
                            newdef = lappend(newdef, def);
                        else
                            newseqopts = lappend(newseqopts, def);
                    }

                    attnum = get_attnum(relid, cmd->name);
                    if (attnum == InvalidAttrNumber)
                        ereport(ERROR,
                                (errcode(ERRCODE_UNDEFINED_COLUMN),
                                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                                        cmd->name, RelationGetRelationName(rel))));

                    seq_relid = getIdentitySequence(relid, attnum, true);

                    if (seq_relid)
                    {
                        AlterSeqStmt *seqstmt;

                        seqstmt = makeNode(AlterSeqStmt);
                        seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
                                                         get_rel_name(seq_relid), -1);
                        seqstmt->options = newseqopts;
                        seqstmt->for_identity = true;
                        seqstmt->missing_ok = false;

                        cxt.blist = lappend(cxt.blist, seqstmt);
                    }

                    /*
                     * If column was not an identity column, we just let the
                     * ALTER TABLE command error out later.  (There are cases
                     * this fails to cover, but we'll need to restructure
                     * where creation of the sequence dependency linkage
                     * happens before we can fix it.)
                     */

                    cmd->def = (Node *) newdef;
                    newcmds = lappend(newcmds, cmd);
                    break;
                }

            case AT_AttachPartition:
            case AT_DetachPartition:
                {
                    PartitionCmd *partcmd = (PartitionCmd *) cmd->def;

                    transformPartitionCmd(&cxt, partcmd);
                    /* assign transformed value of the partition bound */
                    partcmd->bound = cxt.partbound;
                }

                newcmds = lappend(newcmds, cmd);
                break;

            default:

                /*
                 * Currently, we shouldn't actually get here for subcommand
                 * types that don't require transformation; but if we do, just
                 * emit them unchanged.
                 */
                newcmds = lappend(newcmds, cmd);
                break;
        }
    }

    /*
     * Transfer anything we already have in cxt.alist into save_alist, to keep
     * it separate from the output of transformIndexConstraints.
     */
    save_alist = cxt.alist;
    cxt.alist = NIL;

    /* Postprocess constraints */
    transformIndexConstraints(&cxt);
    transformFKConstraints(&cxt, skipValidation, true);
    transformCheckConstraints(&cxt, false);

    /*
     * Push any index-creation commands into the ALTER, so that they can be
     * scheduled nicely by tablecmds.c.  Note that tablecmds.c assumes that
     * the IndexStmt attached to an AT_AddIndex or AT_AddIndexConstraint
     * subcommand has already been through transformIndexStmt.
     */
    foreach(l, cxt.alist)
    {
        Node       *istmt = (Node *) lfirst(l);

        /*
         * We assume here that cxt.alist contains only IndexStmts and possibly
         * ALTER TABLE SET NOT NULL statements generated from primary key
         * constraints.  We absorb the subcommands of the latter directly.
         */
        if (IsA(istmt, IndexStmt))
        {
            IndexStmt  *idxstmt = (IndexStmt *) istmt;

            idxstmt = transformIndexStmt(relid, idxstmt, queryString);
            newcmd = makeNode(AlterTableCmd);
            newcmd->subtype = OidIsValid(idxstmt->indexOid) ? AT_AddIndexConstraint : AT_AddIndex;
            newcmd->def = (Node *) idxstmt;
            newcmds = lappend(newcmds, newcmd);
        }
        else if (IsA(istmt, AlterTableStmt))
        {
            AlterTableStmt *alterstmt = (AlterTableStmt *) istmt;

            newcmds = list_concat(newcmds, alterstmt->cmds);
        }
        else
            elog(ERROR, "unexpected stmt type %d", (int) nodeTag(istmt));
    }
    cxt.alist = NIL;

    /* Append any CHECK or FK constraints to the commands list */
    foreach(l, cxt.ckconstraints)
    {
        newcmd = makeNode(AlterTableCmd);
        newcmd->subtype = AT_AddConstraint;
        newcmd->def = (Node *) lfirst(l);
        newcmds = lappend(newcmds, newcmd);
    }
    foreach(l, cxt.fkconstraints)
    {
        newcmd = makeNode(AlterTableCmd);
        newcmd->subtype = AT_AddConstraint;
        newcmd->def = (Node *) lfirst(l);
        newcmds = lappend(newcmds, newcmd);
    }

    /* Append extended statistic objects */
    transformExtendedStatistics(&cxt);

    /* Close rel */
    relation_close(rel, NoLock);

    /*
     * Output results.
     */
    stmt->cmds = newcmds;

    *beforeStmts = cxt.blist;
    *afterStmts = list_concat(cxt.alist, save_alist);

    return stmt;
}


/*
 * Preprocess a list of column constraint clauses
 * to attach constraint attributes to their primary constraint nodes
 * and detect inconsistent/misplaced constraint attributes.
 *
 * NOTE: currently, attributes are only supported for FOREIGN KEY, UNIQUE,
 * EXCLUSION, and PRIMARY KEY constraints, but someday they ought to be
 * supported for other constraint types.
 */
static void
transformConstraintAttrs(CreateStmtContext *cxt, List *constraintList)
{
    Constraint *lastprimarycon = NULL;
    bool        saw_deferrability = false;
    bool        saw_initially = false;
    ListCell   *clist;

#define SUPPORTS_ATTRS(node)                \
    ((node) != NULL &&                      \
     ((node)->contype == CONSTR_PRIMARY ||  \
      (node)->contype == CONSTR_UNIQUE ||   \
      (node)->contype == CONSTR_EXCLUSION || \
      (node)->contype == CONSTR_FOREIGN))

    foreach(clist, constraintList)
    {
        Constraint *con = (Constraint *) lfirst(clist);

        if (!IsA(con, Constraint))
            elog(ERROR, "unrecognized node type: %d",
                 (int) nodeTag(con));
        switch (con->contype)
        {
            case CONSTR_ATTR_DEFERRABLE:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced DEFERRABLE clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_deferrability)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_deferrability = true;
                lastprimarycon->deferrable = true;
                break;

            case CONSTR_ATTR_NOT_DEFERRABLE:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced NOT DEFERRABLE clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_deferrability)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_deferrability = true;
                lastprimarycon->deferrable = false;
                if (saw_initially &&
                    lastprimarycon->initdeferred)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
                             parser_errposition(cxt->pstate, con->location)));
                break;

            case CONSTR_ATTR_DEFERRED:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced INITIALLY DEFERRED clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_initially)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_initially = true;
                lastprimarycon->initdeferred = true;

                /*
                 * If only INITIALLY DEFERRED appears, assume DEFERRABLE
                 */
                if (!saw_deferrability)
                    lastprimarycon->deferrable = true;
                else if (!lastprimarycon->deferrable)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
                             parser_errposition(cxt->pstate, con->location)));
                break;

            case CONSTR_ATTR_IMMEDIATE:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced INITIALLY IMMEDIATE clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_initially)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_initially = true;
                lastprimarycon->initdeferred = false;
                break;

            default:
                /* Otherwise it's not an attribute */
                lastprimarycon = con;
                /* reset flags for new primary node */
                saw_deferrability = false;
                saw_initially = false;
                break;
        }
    }
}

/*
 * Special handling of type definition for a column
 */
static void
transformColumnType(CreateStmtContext *cxt, ColumnDef *column)
{
    /*
     * All we really need to do here is verify that the type is valid,
     * including any collation spec that might be present.
     */
    Type        ctype = typenameType(cxt->pstate, column->typeName, NULL);

    if (column->collClause)
    {
        Form_pg_type typtup = (Form_pg_type) GETSTRUCT(ctype);

        LookupCollation(cxt->pstate,
                        column->collClause->collname,
                        column->collClause->location);
        /* Complain if COLLATE is applied to an uncollatable type */
        if (!OidIsValid(typtup->typcollation))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("collations are not supported by type %s",
                            format_type_be(typtup->oid)),
                     parser_errposition(cxt->pstate,
                                        column->collClause->location)));
    }

    ReleaseSysCache(ctype);
}


/*
 * transformCreateSchemaStmt -
 *    analyzes the CREATE SCHEMA statement
 *
 * Split the schema element list into individual commands and place
 * them in the result list in an order such that there are no forward
 * references (e.g. GRANT to a table created later in the list). Note
 * that the logic we use for determining forward references is
 * presently quite incomplete.
 *
 * SQL also allows constraints to make forward references, so thumb through
 * the table columns and move forward references to a posterior alter-table
 * command.
 *
 * The result is a list of parse nodes that still need to be analyzed ---
 * but we can't analyze the later commands until we've executed the earlier
 * ones, because of possible inter-object references.
 *
 * Note: this breaks the rules a little bit by modifying schema-name fields
 * within passed-in structs.  However, the transformation would be the same
 * if done over, so it should be all right to scribble on the input to this
 * extent.
 */
List *
transformCreateSchemaStmt(CreateSchemaStmt *stmt)
{
    CreateSchemaStmtContext cxt;
    List       *result;
    ListCell   *elements;

    cxt.stmtType = "CREATE SCHEMA";
    cxt.schemaname = stmt->schemaname;
    cxt.authrole = (RoleSpec *) stmt->authrole;
    cxt.sequences = NIL;
    cxt.tables = NIL;
    cxt.views = NIL;
    cxt.indexes = NIL;
    cxt.triggers = NIL;
    cxt.grants = NIL;

    /*
     * Run through each schema element in the schema element list. Separate
     * statements by type, and do preliminary analysis.
     */
    foreach(elements, stmt->schemaElts)
    {
        Node       *element = lfirst(elements);

        switch (nodeTag(element))
        {
            case T_CreateSeqStmt:
                {
                    CreateSeqStmt *elp = (CreateSeqStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->sequence->schemaname);
                    cxt.sequences = lappend(cxt.sequences, element);
                }
                break;

            case T_CreateStmt:
                {
                    CreateStmt *elp = (CreateStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->relation->schemaname);

                    /*
                     * XXX todo: deal with constraints
                     */
                    cxt.tables = lappend(cxt.tables, element);
                }
                break;

            case T_ViewStmt:
                {
                    ViewStmt   *elp = (ViewStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->view->schemaname);

                    /*
                     * XXX todo: deal with references between views
                     */
                    cxt.views = lappend(cxt.views, element);
                }
                break;

            case T_IndexStmt:
                {
                    IndexStmt  *elp = (IndexStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->relation->schemaname);
                    cxt.indexes = lappend(cxt.indexes, element);
                }
                break;

            case T_CreateTrigStmt:
                {
                    CreateTrigStmt *elp = (CreateTrigStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->relation->schemaname);
                    cxt.triggers = lappend(cxt.triggers, element);
                }
                break;

            case T_GrantStmt:
                cxt.grants = lappend(cxt.grants, element);
                break;

            default:
                elog(ERROR, "unrecognized node type: %d",
                     (int) nodeTag(element));
        }
    }

    result = NIL;
    result = list_concat(result, cxt.sequences);
    result = list_concat(result, cxt.tables);
    result = list_concat(result, cxt.views);
    result = list_concat(result, cxt.indexes);
    result = list_concat(result, cxt.triggers);
    result = list_concat(result, cxt.grants);

    return result;
}

/*
 * setSchemaName
 *      Set or check schema name in an element of a CREATE SCHEMA command
 */
static void
setSchemaName(char *context_schema, char **stmt_schema_name)
{
    if (*stmt_schema_name == NULL)
        *stmt_schema_name = context_schema;
    else if (strcmp(context_schema, *stmt_schema_name) != 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_SCHEMA_DEFINITION),
                 errmsg("CREATE specifies a schema (%s) "
                        "different from the one being created (%s)",
                        *stmt_schema_name, context_schema)));
}

/*
 * transformPartitionCmd
 *      Analyze the ATTACH/DETACH PARTITION command
 *
 * In case of the ATTACH PARTITION command, cxt->partbound is set to the
 * transformed value of cmd->bound.
 */
static void
transformPartitionCmd(CreateStmtContext *cxt, PartitionCmd *cmd)
{
    Relation    parentRel = cxt->rel;

    switch (parentRel->rd_rel->relkind)
    {
        case RELKIND_PARTITIONED_TABLE:
            /* transform the partition bound, if any */
            Assert(RelationGetPartitionKey(parentRel) != NULL);
            if (cmd->bound != NULL)
                cxt->partbound = transformPartitionBound(cxt->pstate, parentRel,
                                                         cmd->bound);
            break;
        case RELKIND_PARTITIONED_INDEX:

            /*
             * A partitioned index cannot have a partition bound set.  ALTER
             * INDEX prevents that with its grammar, but not ALTER TABLE.
             */
            if (cmd->bound != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("\"%s\" is not a partitioned table",
                                RelationGetRelationName(parentRel))));
            break;
        case RELKIND_RELATION:
            /* the table must be partitioned */
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("table \"%s\" is not partitioned",
                            RelationGetRelationName(parentRel))));
            break;
        case RELKIND_INDEX:
            /* the index must be partitioned */
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("index \"%s\" is not partitioned",
                            RelationGetRelationName(parentRel))));
            break;
        default:
            /* parser shouldn't let this case through */
            elog(ERROR, "\"%s\" is not a partitioned table or index",
                 RelationGetRelationName(parentRel));
            break;
    }
}

/*
 * transformPartitionBound
 *
 * Transform a partition bound specification
 */
PartitionBoundSpec *
transformPartitionBound(ParseState *pstate, Relation parent,
                        PartitionBoundSpec *spec)
{
    PartitionBoundSpec *result_spec;
    PartitionKey key = RelationGetPartitionKey(parent);
    char        strategy = get_partition_strategy(key);
    int         partnatts = get_partition_natts(key);
    List       *partexprs = get_partition_exprs(key);

    /* Avoid scribbling on input */
    result_spec = copyObject(spec);

    if (spec->is_default)
    {
        /*
         * Hash partitioning does not support a default partition; there's no
         * use case for it (since the set of partitions to create is perfectly
         * defined), and if users do get into it accidentally, it's hard to
         * back out from it afterwards.
         */
        if (strategy == PARTITION_STRATEGY_HASH)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("a hash-partitioned table may not have a default partition")));

        /*
         * In case of the default partition, parser had no way to identify the
         * partition strategy. Assign the parent's strategy to the default
         * partition bound spec.
         */
        result_spec->strategy = strategy;

        return result_spec;
    }

    if (strategy == PARTITION_STRATEGY_HASH)
    {
        if (spec->strategy != PARTITION_STRATEGY_HASH)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("invalid bound specification for a hash partition"),
                     parser_errposition(pstate, exprLocation((Node *) spec))));

        if (spec->modulus <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("modulus for hash partition must be a positive integer")));

        Assert(spec->remainder >= 0);

        if (spec->remainder >= spec->modulus)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("remainder for hash partition must be less than modulus")));
    }
    else if (strategy == PARTITION_STRATEGY_LIST)
    {
        ListCell   *cell;
        char       *colname;
        Oid         coltype;
        int32       coltypmod;
        Oid         partcollation;

        if (spec->strategy != PARTITION_STRATEGY_LIST)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("invalid bound specification for a list partition"),
                     parser_errposition(pstate, exprLocation((Node *) spec))));

        /* Get the only column's name in case we need to output an error */
        if (key->partattrs[0] != 0)
            colname = get_attname(RelationGetRelid(parent),
                                  key->partattrs[0], false);
        else
            colname = deparse_expression((Node *) linitial(partexprs),
                                         deparse_context_for(RelationGetRelationName(parent),
                                                             RelationGetRelid(parent)),
                                         false, false);
        /* Need its type data too */
        coltype = get_partition_col_typid(key, 0);
        coltypmod = get_partition_col_typmod(key, 0);
        partcollation = get_partition_col_collation(key, 0);

        result_spec->listdatums = NIL;
        foreach(cell, spec->listdatums)
        {
            Node       *expr = lfirst(cell);
            Const      *value;
            ListCell   *cell2;
            bool        duplicate;

            value = transformPartitionBoundValue(pstate, expr,
                                                 colname, coltype, coltypmod,
                                                 partcollation);

            /* Don't add to the result if the value is a duplicate */
            duplicate = false;
            foreach(cell2, result_spec->listdatums)
            {
                Const      *value2 = castNode(Const, lfirst(cell2));

                if (equal(value, value2))
                {
                    duplicate = true;
                    break;
                }
            }
            if (duplicate)
                continue;

            result_spec->listdatums = lappend(result_spec->listdatums,
                                              value);
        }
    }
    else if (strategy == PARTITION_STRATEGY_RANGE)
    {
        if (spec->strategy != PARTITION_STRATEGY_RANGE)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("invalid bound specification for a range partition"),
                     parser_errposition(pstate, exprLocation((Node *) spec))));

        if (list_length(spec->lowerdatums) != partnatts)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("FROM must specify exactly one value per partitioning column")));
        if (list_length(spec->upperdatums) != partnatts)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("TO must specify exactly one value per partitioning column")));

        /*
         * Convert raw parse nodes into PartitionRangeDatum nodes and perform
         * any necessary validation.
         */
        result_spec->lowerdatums =
            transformPartitionRangeBounds(pstate, spec->lowerdatums,
                                          parent);
        result_spec->upperdatums =
            transformPartitionRangeBounds(pstate, spec->upperdatums,
                                          parent);
    }
    else
        elog(ERROR, "unexpected partition strategy: %d", (int) strategy);

    return result_spec;
}

/*
 * transformPartitionRangeBounds
 *      This converts the expressions for range partition bounds from the raw
 *      grammar representation to PartitionRangeDatum structs
 */
static List *
transformPartitionRangeBounds(ParseState *pstate, List *blist,
                              Relation parent)
{
    List       *result = NIL;
    PartitionKey key = RelationGetPartitionKey(parent);
    List       *partexprs = get_partition_exprs(key);
    ListCell   *lc;
    int         i,
                j;

    i = j = 0;
    foreach(lc, blist)
    {
        Node       *expr = lfirst(lc);
        PartitionRangeDatum *prd = NULL;

        /*
         * Infinite range bounds -- "minvalue" and "maxvalue" -- get passed in
         * as ColumnRefs.
         */
        if (IsA(expr, ColumnRef))
        {
            ColumnRef  *cref = (ColumnRef *) expr;
            char       *cname = NULL;

            /*
             * There should be a single field named either "minvalue" or
             * "maxvalue".
             */
            if (list_length(cref->fields) == 1 &&
                IsA(linitial(cref->fields), String))
                cname = strVal(linitial(cref->fields));

            if (cname == NULL)
            {
                /*
                 * ColumnRef is not in the desired single-field-name form. For
                 * consistency between all partition strategies, let the
                 * expression transformation report any errors rather than
                 * doing it ourselves.
                 */
            }
            else if (strcmp("minvalue", cname) == 0)
            {
                prd = makeNode(PartitionRangeDatum);
                prd->kind = PARTITION_RANGE_DATUM_MINVALUE;
                prd->value = NULL;
            }
            else if (strcmp("maxvalue", cname) == 0)
            {
                prd = makeNode(PartitionRangeDatum);
                prd->kind = PARTITION_RANGE_DATUM_MAXVALUE;
                prd->value = NULL;
            }
        }

        if (prd == NULL)
        {
            char       *colname;
            Oid         coltype;
            int32       coltypmod;
            Oid         partcollation;
            Const      *value;

            /* Get the column's name in case we need to output an error */
            if (key->partattrs[i] != 0)
                colname = get_attname(RelationGetRelid(parent),
                                      key->partattrs[i], false);
            else
            {
                colname = deparse_expression((Node *) list_nth(partexprs, j),
                                             deparse_context_for(RelationGetRelationName(parent),
                                                                 RelationGetRelid(parent)),
                                             false, false);
                ++j;
            }

            /* Need its type data too */
            coltype = get_partition_col_typid(key, i);
            coltypmod = get_partition_col_typmod(key, i);
            partcollation = get_partition_col_collation(key, i);

            value = transformPartitionBoundValue(pstate, expr,
                                                 colname,
                                                 coltype, coltypmod,
                                                 partcollation);
            if (value->constisnull)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("cannot specify NULL in range bound")));
            prd = makeNode(PartitionRangeDatum);
            prd->kind = PARTITION_RANGE_DATUM_VALUE;
            prd->value = (Node *) value;
            ++i;
        }

        prd->location = exprLocation(expr);

        result = lappend(result, prd);
    }

    /*
     * Once we see MINVALUE or MAXVALUE for one column, the remaining columns
     * must be the same.
     */
    validateInfiniteBounds(pstate, result);

    return result;
}

/*
 * validateInfiniteBounds
 *
 * Check that a MAXVALUE or MINVALUE specification in a partition bound is
 * followed only by more of the same.
 */
static void
validateInfiniteBounds(ParseState *pstate, List *blist)
{
    ListCell   *lc;
    PartitionRangeDatumKind kind = PARTITION_RANGE_DATUM_VALUE;

    foreach(lc, blist)
    {
        PartitionRangeDatum *prd = castNode(PartitionRangeDatum, lfirst(lc));

        if (kind == prd->kind)
            continue;

        switch (kind)
        {
            case PARTITION_RANGE_DATUM_VALUE:
                kind = prd->kind;
                break;

            case PARTITION_RANGE_DATUM_MAXVALUE:
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("every bound following MAXVALUE must also be MAXVALUE"),
                         parser_errposition(pstate, exprLocation((Node *) prd))));
                break;

            case PARTITION_RANGE_DATUM_MINVALUE:
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("every bound following MINVALUE must also be MINVALUE"),
                         parser_errposition(pstate, exprLocation((Node *) prd))));
                break;
        }
    }
}

/*
 * Transform one entry in a partition bound spec, producing a constant.
 */
static Const *
transformPartitionBoundValue(ParseState *pstate, Node *val,
                             const char *colName, Oid colType, int32 colTypmod,
                             Oid partCollation)
{
    Node       *value;

    /* Transform raw parsetree */
    value = transformExpr(pstate, val, EXPR_KIND_PARTITION_BOUND);

    /*
     * transformExpr() should have already rejected column references,
     * subqueries, aggregates, window functions, and SRFs, based on the
     * EXPR_KIND_ of a partition bound expression.
     */
    Assert(!contain_var_clause(value));

    /*
     * Coerce to the correct type.  This might cause an explicit coercion step
     * to be added on top of the expression, which must be evaluated before
     * returning the result to the caller.
     */
    value = coerce_to_target_type(pstate,
                                  value, exprType(value),
                                  colType,
                                  colTypmod,
                                  COERCION_ASSIGNMENT,
                                  COERCE_IMPLICIT_CAST,
                                  -1);

    if (value == NULL)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("specified value cannot be cast to type %s for column \"%s\"",
                        format_type_be(colType), colName),
                 parser_errposition(pstate, exprLocation(val))));

    /*
     * Evaluate the expression, if needed, assigning the partition key's data
     * type and collation to the resulting Const node.
     */
    if (!IsA(value, Const))
    {
        assign_expr_collations(pstate, value);
        value = (Node *) expression_planner((Expr *) value);
        value = (Node *) evaluate_expr((Expr *) value, colType, colTypmod,
                                       partCollation);
        if (!IsA(value, Const))
            elog(ERROR, "could not evaluate partition bound expression");
    }
    else
    {
        /*
         * If the expression is already a Const, as is often the case, we can
         * skip the rather expensive steps above.  But we still have to insert
         * the right collation, since coerce_to_target_type doesn't handle
         * that.
         */
        ((Const *) value)->constcollid = partCollation;
    }

    /*
     * Attach original expression's parse location to the Const, so that
     * that's what will be reported for any later errors related to this
     * partition bound.
     */
    ((Const *) value)->location = exprLocation(val);

    return (Const *) value;
}