ruleutils.c

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/*-------------------------------------------------------------------------
 *
 * ruleutils.c
 *    Functions to convert stored expressions/querytrees back to
 *    source text
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/ruleutils.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include <ctype.h>
#include <unistd.h>
#include <fcntl.h>
 
#include "access/amapi.h"
#include "access/htup_details.h"
#include "access/relation.h"
#include "access/table.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_am.h"
#include "catalog/pg_authid.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_depend.h"
#include "catalog/pg_language.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_partitioned_table.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_statistic_ext.h"
#include "catalog/pg_trigger.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/tablespace.h"
#include "common/keywords.h"
#include "executor/spi.h"
#include "funcapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "nodes/pathnodes.h"
#include "optimizer/optimizer.h"
#include "parser/parse_agg.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.h"
#include "parser/parse_relation.h"
#include "parser/parser.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
#include "rewrite/rewriteSupport.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/hsearch.h"
#include "utils/lsyscache.h"
#include "utils/partcache.h"
#include "utils/rel.h"
#include "utils/ruleutils.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
#include "utils/varlena.h"
#include "utils/xml.h"
 
/* ----------
 * Pretty formatting constants
 * ----------
 */
 
/* Indent counts */
#define PRETTYINDENT_STD        8
#define PRETTYINDENT_JOIN       4
#define PRETTYINDENT_VAR        4
 
#define PRETTYINDENT_LIMIT      40  /* wrap limit */
 
/* Pretty flags */
#define PRETTYFLAG_PAREN        0x0001
#define PRETTYFLAG_INDENT       0x0002
#define PRETTYFLAG_SCHEMA       0x0004
 
/* Standard conversion of a "bool pretty" option to detailed flags */
#define GET_PRETTY_FLAGS(pretty) \
    ((pretty) ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) \
     : PRETTYFLAG_INDENT)
 
/* Default line length for pretty-print wrapping: 0 means wrap always */
#define WRAP_COLUMN_DEFAULT     0
 
/* macros to test if pretty action needed */
#define PRETTY_PAREN(context)   ((context)->prettyFlags & PRETTYFLAG_PAREN)
#define PRETTY_INDENT(context)  ((context)->prettyFlags & PRETTYFLAG_INDENT)
#define PRETTY_SCHEMA(context)  ((context)->prettyFlags & PRETTYFLAG_SCHEMA)
 
 
/* ----------
 * Local data types
 * ----------
 */
 
/* Context info needed for invoking a recursive querytree display routine */
typedef struct
{
    StringInfo  buf;            /* output buffer to append to */
    List       *namespaces;     /* List of deparse_namespace nodes */
    TupleDesc   resultDesc;     /* if top level of a view, the view's tupdesc */
    List       *targetList;     /* Current query level's SELECT targetlist */
    List       *windowClause;   /* Current query level's WINDOW clause */
    int         prettyFlags;    /* enabling of pretty-print functions */
    int         wrapColumn;     /* max line length, or -1 for no limit */
    int         indentLevel;    /* current indent level for pretty-print */
    bool        varprefix;      /* true to print prefixes on Vars */
    bool        colNamesVisible;    /* do we care about output column names? */
    bool        inGroupBy;      /* deparsing GROUP BY clause? */
    bool        varInOrderBy;   /* deparsing simple Var in ORDER BY? */
    Bitmapset  *appendparents;  /* if not null, map child Vars of these relids
                                 * back to the parent rel */
} deparse_context;
 
/*
 * Each level of query context around a subtree needs a level of Var namespace.
 * A Var having varlevelsup=N refers to the N'th item (counting from 0) in
 * the current context's namespaces list.
 *
 * rtable is the list of actual RTEs from the Query or PlannedStmt.
 * rtable_names holds the alias name to be used for each RTE (either a C
 * string, or NULL for nameless RTEs such as unnamed joins).
 * rtable_columns holds the column alias names to be used for each RTE.
 *
 * subplans is a list of Plan trees for SubPlans and CTEs (it's only used
 * in the PlannedStmt case).
 * ctes is a list of CommonTableExpr nodes (only used in the Query case).
 * appendrels, if not null (it's only used in the PlannedStmt case), is an
 * array of AppendRelInfo nodes, indexed by child relid.  We use that to map
 * child-table Vars to their inheritance parents.
 *
 * In some cases we need to make names of merged JOIN USING columns unique
 * across the whole query, not only per-RTE.  If so, unique_using is true
 * and using_names is a list of C strings representing names already assigned
 * to USING columns.
 *
 * When deparsing plan trees, there is always just a single item in the
 * deparse_namespace list (since a plan tree never contains Vars with
 * varlevelsup > 0).  We store the Plan node that is the immediate
 * parent of the expression to be deparsed, as well as a list of that
 * Plan's ancestors.  In addition, we store its outer and inner subplan nodes,
 * as well as their targetlists, and the index tlist if the current plan node
 * might contain INDEX_VAR Vars.  (These fields could be derived on-the-fly
 * from the current Plan node, but it seems notationally clearer to set them
 * up as separate fields.)
 */
typedef struct
{
    List       *rtable;         /* List of RangeTblEntry nodes */
    List       *rtable_names;   /* Parallel list of names for RTEs */
    List       *rtable_columns; /* Parallel list of deparse_columns structs */
    List       *subplans;       /* List of Plan trees for SubPlans */
    List       *ctes;           /* List of CommonTableExpr nodes */
    AppendRelInfo **appendrels; /* Array of AppendRelInfo nodes, or NULL */
    char       *ret_old_alias;  /* alias for OLD in RETURNING list */
    char       *ret_new_alias;  /* alias for NEW in RETURNING list */
    /* Workspace for column alias assignment: */
    bool        unique_using;   /* Are we making USING names globally unique */
    List       *using_names;    /* List of assigned names for USING columns */
    /* Remaining fields are used only when deparsing a Plan tree: */
    Plan       *plan;           /* immediate parent of current expression */
    List       *ancestors;      /* ancestors of plan */
    Plan       *outer_plan;     /* outer subnode, or NULL if none */
    Plan       *inner_plan;     /* inner subnode, or NULL if none */
    List       *outer_tlist;    /* referent for OUTER_VAR Vars */
    List       *inner_tlist;    /* referent for INNER_VAR Vars */
    List       *index_tlist;    /* referent for INDEX_VAR Vars */
    /* Special namespace representing a function signature: */
    char       *funcname;
    int         numargs;
    char      **argnames;
} deparse_namespace;
 
/*
 * Per-relation data about column alias names.
 *
 * Selecting aliases is unreasonably complicated because of the need to dump
 * rules/views whose underlying tables may have had columns added, deleted, or
 * renamed since the query was parsed.  We must nonetheless print the rule/view
 * in a form that can be reloaded and will produce the same results as before.
 *
 * For each RTE used in the query, we must assign column aliases that are
 * unique within that RTE.  SQL does not require this of the original query,
 * but due to factors such as *-expansion we need to be able to uniquely
 * reference every column in a decompiled query.  As long as we qualify all
 * column references, per-RTE uniqueness is sufficient for that.
 *
 * However, we can't ensure per-column name uniqueness for unnamed join RTEs,
 * since they just inherit column names from their input RTEs, and we can't
 * rename the columns at the join level.  Most of the time this isn't an issue
 * because we don't need to reference the join's output columns as such; we
 * can reference the input columns instead.  That approach can fail for merged
 * JOIN USING columns, however, so when we have one of those in an unnamed
 * join, we have to make that column's alias globally unique across the whole
 * query to ensure it can be referenced unambiguously.
 *
 * Another problem is that a JOIN USING clause requires the columns to be
 * merged to have the same aliases in both input RTEs, and that no other
 * columns in those RTEs or their children conflict with the USING names.
 * To handle that, we do USING-column alias assignment in a recursive
 * traversal of the query's jointree.  When descending through a JOIN with
 * USING, we preassign the USING column names to the child columns, overriding
 * other rules for column alias assignment.  We also mark each RTE with a list
 * of all USING column names selected for joins containing that RTE, so that
 * when we assign other columns' aliases later, we can avoid conflicts.
 *
 * Another problem is that if a JOIN's input tables have had columns added or
 * deleted since the query was parsed, we must generate a column alias list
 * for the join that matches the current set of input columns --- otherwise, a
 * change in the number of columns in the left input would throw off matching
 * of aliases to columns of the right input.  Thus, positions in the printable
 * column alias list are not necessarily one-for-one with varattnos of the
 * JOIN, so we need a separate new_colnames[] array for printing purposes.
 *
 * Finally, when dealing with wide tables we risk O(N^2) costs in assigning
 * non-duplicate column names.  We ameliorate that by using a hash table that
 * holds all the strings appearing in colnames, new_colnames, and parentUsing.
 */
typedef struct
{
    /*
     * colnames is an array containing column aliases to use for columns that
     * existed when the query was parsed.  Dropped columns have NULL entries.
     * This array can be directly indexed by varattno to get a Var's name.
     *
     * Non-NULL entries are guaranteed unique within the RTE, *except* when
     * this is for an unnamed JOIN RTE.  In that case we merely copy up names
     * from the two input RTEs.
     *
     * During the recursive descent in set_using_names(), forcible assignment
     * of a child RTE's column name is represented by pre-setting that element
     * of the child's colnames array.  So at that stage, NULL entries in this
     * array just mean that no name has been preassigned, not necessarily that
     * the column is dropped.
     */
    int         num_cols;       /* length of colnames[] array */
    char      **colnames;       /* array of C strings and NULLs */
 
    /*
     * new_colnames is an array containing column aliases to use for columns
     * that would exist if the query was re-parsed against the current
     * definitions of its base tables.  This is what to print as the column
     * alias list for the RTE.  This array does not include dropped columns,
     * but it will include columns added since original parsing.  Indexes in
     * it therefore have little to do with current varattno values.  As above,
     * entries are unique unless this is for an unnamed JOIN RTE.  (In such an
     * RTE, we never actually print this array, but we must compute it anyway
     * for possible use in computing column names of upper joins.) The
     * parallel array is_new_col marks which of these columns are new since
     * original parsing.  Entries with is_new_col false must match the
     * non-NULL colnames entries one-for-one.
     */
    int         num_new_cols;   /* length of new_colnames[] array */
    char      **new_colnames;   /* array of C strings */
    bool       *is_new_col;     /* array of bool flags */
 
    /* This flag tells whether we should actually print a column alias list */
    bool        printaliases;
 
    /* This list has all names used as USING names in joins above this RTE */
    List       *parentUsing;    /* names assigned to parent merged columns */
 
    /*
     * If this struct is for a JOIN RTE, we fill these fields during the
     * set_using_names() pass to describe its relationship to its child RTEs.
     *
     * leftattnos and rightattnos are arrays with one entry per existing
     * output column of the join (hence, indexable by join varattno).  For a
     * simple reference to a column of the left child, leftattnos[i] is the
     * child RTE's attno and rightattnos[i] is zero; and conversely for a
     * column of the right child.  But for merged columns produced by JOIN
     * USING/NATURAL JOIN, both leftattnos[i] and rightattnos[i] are nonzero.
     * Note that a simple reference might be to a child RTE column that's been
     * dropped; but that's OK since the column could not be used in the query.
     *
     * If it's a JOIN USING, usingNames holds the alias names selected for the
     * merged columns (these might be different from the original USING list,
     * if we had to modify names to achieve uniqueness).
     */
    int         leftrti;        /* rangetable index of left child */
    int         rightrti;       /* rangetable index of right child */
    int        *leftattnos;     /* left-child varattnos of join cols, or 0 */
    int        *rightattnos;    /* right-child varattnos of join cols, or 0 */
    List       *usingNames;     /* names assigned to merged columns */
 
    /*
     * Hash table holding copies of all the strings appearing in this struct's
     * colnames, new_colnames, and parentUsing.  We use a hash table only for
     * sufficiently wide relations, and only during the colname-assignment
     * functions set_relation_column_names and set_join_column_names;
     * otherwise, names_hash is NULL.
     */
    HTAB       *names_hash;     /* entries are just strings */
} deparse_columns;
 
/* This macro is analogous to rt_fetch(), but for deparse_columns structs */
#define deparse_columns_fetch(rangetable_index, dpns) \
    ((deparse_columns *) list_nth((dpns)->rtable_columns, (rangetable_index)-1))
 
/*
 * Entry in set_rtable_names' hash table
 */
typedef struct
{
    char        name[NAMEDATALEN];  /* Hash key --- must be first */
    int         counter;        /* Largest addition used so far for name */
} NameHashEntry;
 
/* Callback signature for resolve_special_varno() */
typedef void (*rsv_callback) (Node *node, deparse_context *context,
                              void *callback_arg);
 
 
/* ----------
 * Global data
 * ----------
 */
static SPIPlanPtr plan_getrulebyoid = NULL;
static const char *const query_getrulebyoid = "SELECT * FROM pg_catalog.pg_rewrite WHERE oid = $1";
static SPIPlanPtr plan_getviewrule = NULL;
static const char *const query_getviewrule = "SELECT * FROM pg_catalog.pg_rewrite WHERE ev_class = $1 AND rulename = $2";
 
/* GUC parameters */
bool        quote_all_identifiers = false;
 
 
/* ----------
 * Local functions
 *
 * Most of these functions used to use fixed-size buffers to build their
 * results.  Now, they take an (already initialized) StringInfo object
 * as a parameter, and append their text output to its contents.
 * ----------
 */
static char *deparse_expression_pretty(Node *expr, List *dpcontext,
                                       bool forceprefix, bool showimplicit,
                                       int prettyFlags, int startIndent);
static char *pg_get_viewdef_worker(Oid viewoid,
                                   int prettyFlags, int wrapColumn);
static char *pg_get_triggerdef_worker(Oid trigid, bool pretty);
static int  decompile_column_index_array(Datum column_index_array, Oid relId,
                                         bool withPeriod, StringInfo buf);
static char *pg_get_ruledef_worker(Oid ruleoid, int prettyFlags);
static char *pg_get_indexdef_worker(Oid indexrelid, int colno,
                                    const Oid *excludeOps,
                                    bool attrsOnly, bool keysOnly,
                                    bool showTblSpc, bool inherits,
                                    int prettyFlags, bool missing_ok);
static char *pg_get_statisticsobj_worker(Oid statextid, bool columns_only,
                                         bool missing_ok);
static char *pg_get_partkeydef_worker(Oid relid, int prettyFlags,
                                      bool attrsOnly, bool missing_ok);
static char *pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
                                         int prettyFlags, bool missing_ok);
static text *pg_get_expr_worker(text *expr, Oid relid, int prettyFlags);
static int  print_function_arguments(StringInfo buf, HeapTuple proctup,
                                     bool print_table_args, bool print_defaults);
static void print_function_rettype(StringInfo buf, HeapTuple proctup);
static void print_function_trftypes(StringInfo buf, HeapTuple proctup);
static void print_function_sqlbody(StringInfo buf, HeapTuple proctup);
static void set_rtable_names(deparse_namespace *dpns, List *parent_namespaces,
                             Bitmapset *rels_used);
static void set_deparse_for_query(deparse_namespace *dpns, Query *query,
                                  List *parent_namespaces);
static void set_simple_column_names(deparse_namespace *dpns);
static bool has_dangerous_join_using(deparse_namespace *dpns, Node *jtnode);
static void set_using_names(deparse_namespace *dpns, Node *jtnode,
                            List *parentUsing);
static void set_relation_column_names(deparse_namespace *dpns,
                                      RangeTblEntry *rte,
                                      deparse_columns *colinfo);
static void set_join_column_names(deparse_namespace *dpns, RangeTblEntry *rte,
                                  deparse_columns *colinfo);
static bool colname_is_unique(const char *colname, deparse_namespace *dpns,
                              deparse_columns *colinfo);
static char *make_colname_unique(char *colname, deparse_namespace *dpns,
                                 deparse_columns *colinfo);
static void expand_colnames_array_to(deparse_columns *colinfo, int n);
static void build_colinfo_names_hash(deparse_columns *colinfo);
static void add_to_names_hash(deparse_columns *colinfo, const char *name);
static void destroy_colinfo_names_hash(deparse_columns *colinfo);
static void identify_join_columns(JoinExpr *j, RangeTblEntry *jrte,
                                  deparse_columns *colinfo);
static char *get_rtable_name(int rtindex, deparse_context *context);
static void set_deparse_plan(deparse_namespace *dpns, Plan *plan);
static Plan *find_recursive_union(deparse_namespace *dpns,
                                  WorkTableScan *wtscan);
static void push_child_plan(deparse_namespace *dpns, Plan *plan,
                            deparse_namespace *save_dpns);
static void pop_child_plan(deparse_namespace *dpns,
                           deparse_namespace *save_dpns);
static void push_ancestor_plan(deparse_namespace *dpns, ListCell *ancestor_cell,
                               deparse_namespace *save_dpns);
static void pop_ancestor_plan(deparse_namespace *dpns,
                              deparse_namespace *save_dpns);
static void make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
                         int prettyFlags);
static void make_viewdef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
                         int prettyFlags, int wrapColumn);
static void get_query_def(Query *query, StringInfo buf, List *parentnamespace,
                          TupleDesc resultDesc, bool colNamesVisible,
                          int prettyFlags, int wrapColumn, int startIndent);
static void get_values_def(List *values_lists, deparse_context *context);
static void get_with_clause(Query *query, deparse_context *context);
static void get_select_query_def(Query *query, deparse_context *context);
static void get_insert_query_def(Query *query, deparse_context *context);
static void get_update_query_def(Query *query, deparse_context *context);
static void get_update_query_targetlist_def(Query *query, List *targetList,
                                            deparse_context *context,
                                            RangeTblEntry *rte);
static void get_delete_query_def(Query *query, deparse_context *context);
static void get_merge_query_def(Query *query, deparse_context *context);
static void get_utility_query_def(Query *query, deparse_context *context);
static void get_basic_select_query(Query *query, deparse_context *context);
static void get_target_list(List *targetList, deparse_context *context);
static void get_returning_clause(Query *query, deparse_context *context);
static void get_setop_query(Node *setOp, Query *query,
                            deparse_context *context);
static Node *get_rule_sortgroupclause(Index ref, List *tlist,
                                      bool force_colno,
                                      deparse_context *context);
static void get_rule_groupingset(GroupingSet *gset, List *targetlist,
                                 bool omit_parens, deparse_context *context);
static void get_rule_orderby(List *orderList, List *targetList,
                             bool force_colno, deparse_context *context);
static void get_rule_windowclause(Query *query, deparse_context *context);
static void get_rule_windowspec(WindowClause *wc, List *targetList,
                                deparse_context *context);
static void get_window_frame_options(int frameOptions,
                                     Node *startOffset, Node *endOffset,
                                     deparse_context *context);
static char *get_variable(Var *var, int levelsup, bool istoplevel,
                          deparse_context *context);
static void get_special_variable(Node *node, deparse_context *context,
                                 void *callback_arg);
static void resolve_special_varno(Node *node, deparse_context *context,
                                  rsv_callback callback, void *callback_arg);
static Node *find_param_referent(Param *param, deparse_context *context,
                                 deparse_namespace **dpns_p, ListCell **ancestor_cell_p);
static SubPlan *find_param_generator(Param *param, deparse_context *context,
                                     int *column_p);
static SubPlan *find_param_generator_initplan(Param *param, Plan *plan,
                                              int *column_p);
static void get_parameter(Param *param, deparse_context *context);
static const char *get_simple_binary_op_name(OpExpr *expr);
static bool isSimpleNode(Node *node, Node *parentNode, int prettyFlags);
static void appendContextKeyword(deparse_context *context, const char *str,
                                 int indentBefore, int indentAfter, int indentPlus);
static void removeStringInfoSpaces(StringInfo str);
static void get_rule_expr(Node *node, deparse_context *context,
                          bool showimplicit);
static void get_rule_expr_toplevel(Node *node, deparse_context *context,
                                   bool showimplicit);
static void get_rule_list_toplevel(List *lst, deparse_context *context,
                                   bool showimplicit);
static void get_rule_expr_funccall(Node *node, deparse_context *context,
                                   bool showimplicit);
static bool looks_like_function(Node *node);
static void get_oper_expr(OpExpr *expr, deparse_context *context);
static void get_func_expr(FuncExpr *expr, deparse_context *context,
                          bool showimplicit);
static void get_agg_expr(Aggref *aggref, deparse_context *context,
                         Aggref *original_aggref);
static void get_agg_expr_helper(Aggref *aggref, deparse_context *context,
                                Aggref *original_aggref, const char *funcname,
                                const char *options, bool is_json_objectagg);
static void get_agg_combine_expr(Node *node, deparse_context *context,
                                 void *callback_arg);
static void get_windowfunc_expr(WindowFunc *wfunc, deparse_context *context);
static void get_windowfunc_expr_helper(WindowFunc *wfunc, deparse_context *context,
                                       const char *funcname, const char *options,
                                       bool is_json_objectagg);
static bool get_func_sql_syntax(FuncExpr *expr, deparse_context *context);
static void get_coercion_expr(Node *arg, deparse_context *context,
                              Oid resulttype, int32 resulttypmod,
                              Node *parentNode);
static void get_const_expr(Const *constval, deparse_context *context,
                           int showtype);
static void get_const_collation(Const *constval, deparse_context *context);
static void get_json_format(JsonFormat *format, StringInfo buf);
static void get_json_returning(JsonReturning *returning, StringInfo buf,
                               bool json_format_by_default);
static void get_json_constructor(JsonConstructorExpr *ctor,
                                 deparse_context *context, bool showimplicit);
static void get_json_constructor_options(JsonConstructorExpr *ctor,
                                         StringInfo buf);
static void get_json_agg_constructor(JsonConstructorExpr *ctor,
                                     deparse_context *context,
                                     const char *funcname,
                                     bool is_json_objectagg);
static void simple_quote_literal(StringInfo buf, const char *val);
static void get_sublink_expr(SubLink *sublink, deparse_context *context);
static void get_tablefunc(TableFunc *tf, deparse_context *context,
                          bool showimplicit);
static void get_from_clause(Query *query, const char *prefix,
                            deparse_context *context);
static void get_from_clause_item(Node *jtnode, Query *query,
                                 deparse_context *context);
static void get_rte_alias(RangeTblEntry *rte, int varno, bool use_as,
                          deparse_context *context);
static void get_column_alias_list(deparse_columns *colinfo,
                                  deparse_context *context);
static void get_from_clause_coldeflist(RangeTblFunction *rtfunc,
                                       deparse_columns *colinfo,
                                       deparse_context *context);
static void get_tablesample_def(TableSampleClause *tablesample,
                                deparse_context *context);
static void get_opclass_name(Oid opclass, Oid actual_datatype,
                             StringInfo buf);
static Node *processIndirection(Node *node, deparse_context *context);
static void printSubscripts(SubscriptingRef *sbsref, deparse_context *context);
static char *get_relation_name(Oid relid);
static char *generate_relation_name(Oid relid, List *namespaces);
static char *generate_qualified_relation_name(Oid relid);
static char *generate_function_name(Oid funcid, int nargs,
                                    List *argnames, Oid *argtypes,
                                    bool has_variadic, bool *use_variadic_p,
                                    bool inGroupBy);
static char *generate_operator_name(Oid operid, Oid arg1, Oid arg2);
static void add_cast_to(StringInfo buf, Oid typid);
static char *generate_qualified_type_name(Oid typid);
static text *string_to_text(char *str);
static char *flatten_reloptions(Oid relid);
static void get_reloptions(StringInfo buf, Datum reloptions);
static void get_json_path_spec(Node *path_spec, deparse_context *context,
                               bool showimplicit);
static void get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
                                   deparse_context *context,
                                   bool showimplicit);
static void get_json_table_nested_columns(TableFunc *tf, JsonTablePlan *plan,
                                          deparse_context *context,
                                          bool showimplicit,
                                          bool needcomma);
 
#define only_marker(rte)  ((rte)->inh ? "" : "ONLY ")
 
 
/* ----------
 * pg_get_ruledef       - Do it all and return a text
 *                that could be used as a statement
 *                to recreate the rule
 * ----------
 */
Datum
pg_get_ruledef(PG_FUNCTION_ARGS)
{
    Oid         ruleoid = PG_GETARG_OID(0);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = PRETTYFLAG_INDENT;
 
    res = pg_get_ruledef_worker(ruleoid, prettyFlags);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
 
Datum
pg_get_ruledef_ext(PG_FUNCTION_ARGS)
{
    Oid         ruleoid = PG_GETARG_OID(0);
    bool        pretty = PG_GETARG_BOOL(1);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    res = pg_get_ruledef_worker(ruleoid, prettyFlags);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
 
static char *
pg_get_ruledef_worker(Oid ruleoid, int prettyFlags)
{
    Datum       args[1];
    char        nulls[1];
    int         spirc;
    HeapTuple   ruletup;
    TupleDesc   rulettc;
    StringInfoData buf;
 
    /*
     * Do this first so that string is alloc'd in outer context not SPI's.
     */
    initStringInfo(&buf);
 
    /*
     * Connect to SPI manager
     */
    SPI_connect();
 
    /*
     * On the first call prepare the plan to lookup pg_rewrite. We read
     * pg_rewrite over the SPI manager instead of using the syscache to be
     * checked for read access on pg_rewrite.
     */
    if (plan_getrulebyoid == NULL)
    {
        Oid         argtypes[1];
        SPIPlanPtr  plan;
 
        argtypes[0] = OIDOID;
        plan = SPI_prepare(query_getrulebyoid, 1, argtypes);
        if (plan == NULL)
            elog(ERROR, "SPI_prepare failed for \"%s\"", query_getrulebyoid);
        SPI_keepplan(plan);
        plan_getrulebyoid = plan;
    }
 
    /*
     * Get the pg_rewrite tuple for this rule
     */
    args[0] = ObjectIdGetDatum(ruleoid);
    nulls[0] = ' ';
    spirc = SPI_execute_plan(plan_getrulebyoid, args, nulls, true, 0);
    if (spirc != SPI_OK_SELECT)
        elog(ERROR, "failed to get pg_rewrite tuple for rule %u", ruleoid);
    if (SPI_processed != 1)
    {
        /*
         * There is no tuple data available here, just keep the output buffer
         * empty.
         */
    }
    else
    {
        /*
         * Get the rule's definition and put it into executor's memory
         */
        ruletup = SPI_tuptable->vals[0];
        rulettc = SPI_tuptable->tupdesc;
        make_ruledef(&buf, ruletup, rulettc, prettyFlags);
    }
 
    /*
     * Disconnect from SPI manager
     */
    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "SPI_finish failed");
 
    if (buf.len == 0)
        return NULL;
 
    return buf.data;
}
 
 
/* ----------
 * pg_get_viewdef       - Mainly the same thing, but we
 *                only return the SELECT part of a view
 * ----------
 */
Datum
pg_get_viewdef(PG_FUNCTION_ARGS)
{
    /* By OID */
    Oid         viewoid = PG_GETARG_OID(0);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = PRETTYFLAG_INDENT;
 
    res = pg_get_viewdef_worker(viewoid, prettyFlags, WRAP_COLUMN_DEFAULT);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
 
Datum
pg_get_viewdef_ext(PG_FUNCTION_ARGS)
{
    /* By OID */
    Oid         viewoid = PG_GETARG_OID(0);
    bool        pretty = PG_GETARG_BOOL(1);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    res = pg_get_viewdef_worker(viewoid, prettyFlags, WRAP_COLUMN_DEFAULT);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
Datum
pg_get_viewdef_wrap(PG_FUNCTION_ARGS)
{
    /* By OID */
    Oid         viewoid = PG_GETARG_OID(0);
    int         wrap = PG_GETARG_INT32(1);
    int         prettyFlags;
    char       *res;
 
    /* calling this implies we want pretty printing */
    prettyFlags = GET_PRETTY_FLAGS(true);
 
    res = pg_get_viewdef_worker(viewoid, prettyFlags, wrap);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
Datum
pg_get_viewdef_name(PG_FUNCTION_ARGS)
{
    /* By qualified name */
    text       *viewname = PG_GETARG_TEXT_PP(0);
    int         prettyFlags;
    RangeVar   *viewrel;
    Oid         viewoid;
    char       *res;
 
    prettyFlags = PRETTYFLAG_INDENT;
 
    /* Look up view name.  Can't lock it - we might not have privileges. */
    viewrel = makeRangeVarFromNameList(textToQualifiedNameList(viewname));
    viewoid = RangeVarGetRelid(viewrel, NoLock, false);
 
    res = pg_get_viewdef_worker(viewoid, prettyFlags, WRAP_COLUMN_DEFAULT);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
 
Datum
pg_get_viewdef_name_ext(PG_FUNCTION_ARGS)
{
    /* By qualified name */
    text       *viewname = PG_GETARG_TEXT_PP(0);
    bool        pretty = PG_GETARG_BOOL(1);
    int         prettyFlags;
    RangeVar   *viewrel;
    Oid         viewoid;
    char       *res;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    /* Look up view name.  Can't lock it - we might not have privileges. */
    viewrel = makeRangeVarFromNameList(textToQualifiedNameList(viewname));
    viewoid = RangeVarGetRelid(viewrel, NoLock, false);
 
    res = pg_get_viewdef_worker(viewoid, prettyFlags, WRAP_COLUMN_DEFAULT);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
/*
 * Common code for by-OID and by-name variants of pg_get_viewdef
 */
static char *
pg_get_viewdef_worker(Oid viewoid, int prettyFlags, int wrapColumn)
{
    Datum       args[2];
    char        nulls[2];
    int         spirc;
    HeapTuple   ruletup;
    TupleDesc   rulettc;
    StringInfoData buf;
 
    /*
     * Do this first so that string is alloc'd in outer context not SPI's.
     */
    initStringInfo(&buf);
 
    /*
     * Connect to SPI manager
     */
    SPI_connect();
 
    /*
     * On the first call prepare the plan to lookup pg_rewrite. We read
     * pg_rewrite over the SPI manager instead of using the syscache to be
     * checked for read access on pg_rewrite.
     */
    if (plan_getviewrule == NULL)
    {
        Oid         argtypes[2];
        SPIPlanPtr  plan;
 
        argtypes[0] = OIDOID;
        argtypes[1] = NAMEOID;
        plan = SPI_prepare(query_getviewrule, 2, argtypes);
        if (plan == NULL)
            elog(ERROR, "SPI_prepare failed for \"%s\"", query_getviewrule);
        SPI_keepplan(plan);
        plan_getviewrule = plan;
    }
 
    /*
     * Get the pg_rewrite tuple for the view's SELECT rule
     */
    args[0] = ObjectIdGetDatum(viewoid);
    args[1] = DirectFunctionCall1(namein, CStringGetDatum(ViewSelectRuleName));
    nulls[0] = ' ';
    nulls[1] = ' ';
    spirc = SPI_execute_plan(plan_getviewrule, args, nulls, true, 0);
    if (spirc != SPI_OK_SELECT)
        elog(ERROR, "failed to get pg_rewrite tuple for view %u", viewoid);
    if (SPI_processed != 1)
    {
        /*
         * There is no tuple data available here, just keep the output buffer
         * empty.
         */
    }
    else
    {
        /*
         * Get the rule's definition and put it into executor's memory
         */
        ruletup = SPI_tuptable->vals[0];
        rulettc = SPI_tuptable->tupdesc;
        make_viewdef(&buf, ruletup, rulettc, prettyFlags, wrapColumn);
    }
 
    /*
     * Disconnect from SPI manager
     */
    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "SPI_finish failed");
 
    if (buf.len == 0)
        return NULL;
 
    return buf.data;
}
 
/* ----------
 * pg_get_triggerdef        - Get the definition of a trigger
 * ----------
 */
Datum
pg_get_triggerdef(PG_FUNCTION_ARGS)
{
    Oid         trigid = PG_GETARG_OID(0);
    char       *res;
 
    res = pg_get_triggerdef_worker(trigid, false);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
Datum
pg_get_triggerdef_ext(PG_FUNCTION_ARGS)
{
    Oid         trigid = PG_GETARG_OID(0);
    bool        pretty = PG_GETARG_BOOL(1);
    char       *res;
 
    res = pg_get_triggerdef_worker(trigid, pretty);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
static char *
pg_get_triggerdef_worker(Oid trigid, bool pretty)
{
    HeapTuple   ht_trig;
    Form_pg_trigger trigrec;
    StringInfoData buf;
    Relation    tgrel;
    ScanKeyData skey[1];
    SysScanDesc tgscan;
    int         findx = 0;
    char       *tgname;
    char       *tgoldtable;
    char       *tgnewtable;
    Datum       value;
    bool        isnull;
 
    /*
     * Fetch the pg_trigger tuple by the Oid of the trigger
     */
    tgrel = table_open(TriggerRelationId, AccessShareLock);
 
    ScanKeyInit(&skey[0],
                Anum_pg_trigger_oid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(trigid));
 
    tgscan = systable_beginscan(tgrel, TriggerOidIndexId, true,
                                NULL, 1, skey);
 
    ht_trig = systable_getnext(tgscan);
 
    if (!HeapTupleIsValid(ht_trig))
    {
        systable_endscan(tgscan);
        table_close(tgrel, AccessShareLock);
        return NULL;
    }
 
    trigrec = (Form_pg_trigger) GETSTRUCT(ht_trig);
 
    /*
     * Start the trigger definition. Note that the trigger's name should never
     * be schema-qualified, but the trigger rel's name may be.
     */
    initStringInfo(&buf);
 
    tgname = NameStr(trigrec->tgname);
    appendStringInfo(&buf, "CREATE %sTRIGGER %s ",
                     OidIsValid(trigrec->tgconstraint) ? "CONSTRAINT " : "",
                     quote_identifier(tgname));
 
    if (TRIGGER_FOR_BEFORE(trigrec->tgtype))
        appendStringInfoString(&buf, "BEFORE");
    else if (TRIGGER_FOR_AFTER(trigrec->tgtype))
        appendStringInfoString(&buf, "AFTER");
    else if (TRIGGER_FOR_INSTEAD(trigrec->tgtype))
        appendStringInfoString(&buf, "INSTEAD OF");
    else
        elog(ERROR, "unexpected tgtype value: %d", trigrec->tgtype);
 
    if (TRIGGER_FOR_INSERT(trigrec->tgtype))
    {
        appendStringInfoString(&buf, " INSERT");
        findx++;
    }
    if (TRIGGER_FOR_DELETE(trigrec->tgtype))
    {
        if (findx > 0)
            appendStringInfoString(&buf, " OR DELETE");
        else
            appendStringInfoString(&buf, " DELETE");
        findx++;
    }
    if (TRIGGER_FOR_UPDATE(trigrec->tgtype))
    {
        if (findx > 0)
            appendStringInfoString(&buf, " OR UPDATE");
        else
            appendStringInfoString(&buf, " UPDATE");
        findx++;
        /* tgattr is first var-width field, so OK to access directly */
        if (trigrec->tgattr.dim1 > 0)
        {
            int         i;
 
            appendStringInfoString(&buf, " OF ");
            for (i = 0; i < trigrec->tgattr.dim1; i++)
            {
                char       *attname;
 
                if (i > 0)
                    appendStringInfoString(&buf, ", ");
                attname = get_attname(trigrec->tgrelid,
                                      trigrec->tgattr.values[i], false);
                appendStringInfoString(&buf, quote_identifier(attname));
            }
        }
    }
    if (TRIGGER_FOR_TRUNCATE(trigrec->tgtype))
    {
        if (findx > 0)
            appendStringInfoString(&buf, " OR TRUNCATE");
        else
            appendStringInfoString(&buf, " TRUNCATE");
        findx++;
    }
 
    /*
     * In non-pretty mode, always schema-qualify the target table name for
     * safety.  In pretty mode, schema-qualify only if not visible.
     */
    appendStringInfo(&buf, " ON %s ",
                     pretty ?
                     generate_relation_name(trigrec->tgrelid, NIL) :
                     generate_qualified_relation_name(trigrec->tgrelid));
 
    if (OidIsValid(trigrec->tgconstraint))
    {
        if (OidIsValid(trigrec->tgconstrrelid))
            appendStringInfo(&buf, "FROM %s ",
                             generate_relation_name(trigrec->tgconstrrelid, NIL));
        if (!trigrec->tgdeferrable)
            appendStringInfoString(&buf, "NOT ");
        appendStringInfoString(&buf, "DEFERRABLE INITIALLY ");
        if (trigrec->tginitdeferred)
            appendStringInfoString(&buf, "DEFERRED ");
        else
            appendStringInfoString(&buf, "IMMEDIATE ");
    }
 
    value = fastgetattr(ht_trig, Anum_pg_trigger_tgoldtable,
                        tgrel->rd_att, &isnull);
    if (!isnull)
        tgoldtable = NameStr(*DatumGetName(value));
    else
        tgoldtable = NULL;
    value = fastgetattr(ht_trig, Anum_pg_trigger_tgnewtable,
                        tgrel->rd_att, &isnull);
    if (!isnull)
        tgnewtable = NameStr(*DatumGetName(value));
    else
        tgnewtable = NULL;
    if (tgoldtable != NULL || tgnewtable != NULL)
    {
        appendStringInfoString(&buf, "REFERENCING ");
        if (tgoldtable != NULL)
            appendStringInfo(&buf, "OLD TABLE AS %s ",
                             quote_identifier(tgoldtable));
        if (tgnewtable != NULL)
            appendStringInfo(&buf, "NEW TABLE AS %s ",
                             quote_identifier(tgnewtable));
    }
 
    if (TRIGGER_FOR_ROW(trigrec->tgtype))
        appendStringInfoString(&buf, "FOR EACH ROW ");
    else
        appendStringInfoString(&buf, "FOR EACH STATEMENT ");
 
    /* If the trigger has a WHEN qualification, add that */
    value = fastgetattr(ht_trig, Anum_pg_trigger_tgqual,
                        tgrel->rd_att, &isnull);
    if (!isnull)
    {
        Node       *qual;
        char        relkind;
        deparse_context context;
        deparse_namespace dpns;
        RangeTblEntry *oldrte;
        RangeTblEntry *newrte;
 
        appendStringInfoString(&buf, "WHEN (");
 
        qual = stringToNode(TextDatumGetCString(value));
 
        relkind = get_rel_relkind(trigrec->tgrelid);
 
        /* Build minimal OLD and NEW RTEs for the rel */
        oldrte = makeNode(RangeTblEntry);
        oldrte->rtekind = RTE_RELATION;
        oldrte->relid = trigrec->tgrelid;
        oldrte->relkind = relkind;
        oldrte->rellockmode = AccessShareLock;
        oldrte->alias = makeAlias("old", NIL);
        oldrte->eref = oldrte->alias;
        oldrte->lateral = false;
        oldrte->inh = false;
        oldrte->inFromCl = true;
 
        newrte = makeNode(RangeTblEntry);
        newrte->rtekind = RTE_RELATION;
        newrte->relid = trigrec->tgrelid;
        newrte->relkind = relkind;
        newrte->rellockmode = AccessShareLock;
        newrte->alias = makeAlias("new", NIL);
        newrte->eref = newrte->alias;
        newrte->lateral = false;
        newrte->inh = false;
        newrte->inFromCl = true;
 
        /* Build two-element rtable */
        memset(&dpns, 0, sizeof(dpns));
        dpns.rtable = list_make2(oldrte, newrte);
        dpns.subplans = NIL;
        dpns.ctes = NIL;
        dpns.appendrels = NULL;
        set_rtable_names(&dpns, NIL, NULL);
        set_simple_column_names(&dpns);
 
        /* Set up context with one-deep namespace stack */
        context.buf = &buf;
        context.namespaces = list_make1(&dpns);
        context.resultDesc = NULL;
        context.targetList = NIL;
        context.windowClause = NIL;
        context.varprefix = true;
        context.prettyFlags = GET_PRETTY_FLAGS(pretty);
        context.wrapColumn = WRAP_COLUMN_DEFAULT;
        context.indentLevel = PRETTYINDENT_STD;
        context.colNamesVisible = true;
        context.inGroupBy = false;
        context.varInOrderBy = false;
        context.appendparents = NULL;
 
        get_rule_expr(qual, &context, false);
 
        appendStringInfoString(&buf, ") ");
    }
 
    appendStringInfo(&buf, "EXECUTE FUNCTION %s(",
                     generate_function_name(trigrec->tgfoid, 0,
                                            NIL, NULL,
                                            false, NULL, false));
 
    if (trigrec->tgnargs > 0)
    {
        char       *p;
        int         i;
 
        value = fastgetattr(ht_trig, Anum_pg_trigger_tgargs,
                            tgrel->rd_att, &isnull);
        if (isnull)
            elog(ERROR, "tgargs is null for trigger %u", trigid);
        p = (char *) VARDATA_ANY(DatumGetByteaPP(value));
        for (i = 0; i < trigrec->tgnargs; i++)
        {
            if (i > 0)
                appendStringInfoString(&buf, ", ");
            simple_quote_literal(&buf, p);
            /* advance p to next string embedded in tgargs */
            while (*p)
                p++;
            p++;
        }
    }
 
    /* We deliberately do not put semi-colon at end */
    appendStringInfoChar(&buf, ')');
 
    /* Clean up */
    systable_endscan(tgscan);
 
    table_close(tgrel, AccessShareLock);
 
    return buf.data;
}
 
/* ----------
 * pg_get_indexdef          - Get the definition of an index
 *
 * In the extended version, there is a colno argument as well as pretty bool.
 *  if colno == 0, we want a complete index definition.
 *  if colno > 0, we only want the Nth index key's variable or expression.
 *
 * Note that the SQL-function versions of this omit any info about the
 * index tablespace; this is intentional because pg_dump wants it that way.
 * However pg_get_indexdef_string() includes the index tablespace.
 * ----------
 */
Datum
pg_get_indexdef(PG_FUNCTION_ARGS)
{
    Oid         indexrelid = PG_GETARG_OID(0);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = PRETTYFLAG_INDENT;
 
    res = pg_get_indexdef_worker(indexrelid, 0, NULL,
                                 false, false,
                                 false, false,
                                 prettyFlags, true);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
Datum
pg_get_indexdef_ext(PG_FUNCTION_ARGS)
{
    Oid         indexrelid = PG_GETARG_OID(0);
    int32       colno = PG_GETARG_INT32(1);
    bool        pretty = PG_GETARG_BOOL(2);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    res = pg_get_indexdef_worker(indexrelid, colno, NULL,
                                 colno != 0, false,
                                 false, false,
                                 prettyFlags, true);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
/*
 * Internal version for use by ALTER TABLE.
 * Includes a tablespace clause in the result.
 * Returns a palloc'd C string; no pretty-printing.
 */
char *
pg_get_indexdef_string(Oid indexrelid)
{
    return pg_get_indexdef_worker(indexrelid, 0, NULL,
                                  false, false,
                                  true, true,
                                  0, false);
}
 
/* Internal version that just reports the key-column definitions */
char *
pg_get_indexdef_columns(Oid indexrelid, bool pretty)
{
    int         prettyFlags;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    return pg_get_indexdef_worker(indexrelid, 0, NULL,
                                  true, true,
                                  false, false,
                                  prettyFlags, false);
}
 
/* Internal version, extensible with flags to control its behavior */
char *
pg_get_indexdef_columns_extended(Oid indexrelid, bits16 flags)
{
    bool        pretty = ((flags & RULE_INDEXDEF_PRETTY) != 0);
    bool        keys_only = ((flags & RULE_INDEXDEF_KEYS_ONLY) != 0);
    int         prettyFlags;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    return pg_get_indexdef_worker(indexrelid, 0, NULL,
                                  true, keys_only,
                                  false, false,
                                  prettyFlags, false);
}
 
/*
 * Internal workhorse to decompile an index definition.
 *
 * This is now used for exclusion constraints as well: if excludeOps is not
 * NULL then it points to an array of exclusion operator OIDs.
 */
static char *
pg_get_indexdef_worker(Oid indexrelid, int colno,
                       const Oid *excludeOps,
                       bool attrsOnly, bool keysOnly,
                       bool showTblSpc, bool inherits,
                       int prettyFlags, bool missing_ok)
{
    /* might want a separate isConstraint parameter later */
    bool        isConstraint = (excludeOps != NULL);
    HeapTuple   ht_idx;
    HeapTuple   ht_idxrel;
    HeapTuple   ht_am;
    Form_pg_index idxrec;
    Form_pg_class idxrelrec;
    Form_pg_am  amrec;
    IndexAmRoutine *amroutine;
    List       *indexprs;
    ListCell   *indexpr_item;
    List       *context;
    Oid         indrelid;
    int         keyno;
    Datum       indcollDatum;
    Datum       indclassDatum;
    Datum       indoptionDatum;
    oidvector  *indcollation;
    oidvector  *indclass;
    int2vector *indoption;
    StringInfoData buf;
    char       *str;
    char       *sep;
 
    /*
     * Fetch the pg_index tuple by the Oid of the index
     */
    ht_idx = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexrelid));
    if (!HeapTupleIsValid(ht_idx))
    {
        if (missing_ok)
            return NULL;
        elog(ERROR, "cache lookup failed for index %u", indexrelid);
    }
    idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
 
    indrelid = idxrec->indrelid;
    Assert(indexrelid == idxrec->indexrelid);
 
    /* Must get indcollation, indclass, and indoption the hard way */
    indcollDatum = SysCacheGetAttrNotNull(INDEXRELID, ht_idx,
                                          Anum_pg_index_indcollation);
    indcollation = (oidvector *) DatumGetPointer(indcollDatum);
 
    indclassDatum = SysCacheGetAttrNotNull(INDEXRELID, ht_idx,
                                           Anum_pg_index_indclass);
    indclass = (oidvector *) DatumGetPointer(indclassDatum);
 
    indoptionDatum = SysCacheGetAttrNotNull(INDEXRELID, ht_idx,
                                            Anum_pg_index_indoption);
    indoption = (int2vector *) DatumGetPointer(indoptionDatum);
 
    /*
     * Fetch the pg_class tuple of the index relation
     */
    ht_idxrel = SearchSysCache1(RELOID, ObjectIdGetDatum(indexrelid));
    if (!HeapTupleIsValid(ht_idxrel))
        elog(ERROR, "cache lookup failed for relation %u", indexrelid);
    idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);
 
    /*
     * 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);
 
    /* Fetch the index AM's API struct */
    amroutine = GetIndexAmRoutine(amrec->amhandler);
 
    /*
     * Get the index expressions, if any.  (NOTE: we do not use the relcache
     * versions of the expressions and predicate, because we want to display
     * non-const-folded expressions.)
     */
    if (!heap_attisnull(ht_idx, Anum_pg_index_indexprs, NULL))
    {
        Datum       exprsDatum;
        char       *exprsString;
 
        exprsDatum = SysCacheGetAttrNotNull(INDEXRELID, ht_idx,
                                            Anum_pg_index_indexprs);
        exprsString = TextDatumGetCString(exprsDatum);
        indexprs = (List *) stringToNode(exprsString);
        pfree(exprsString);
    }
    else
        indexprs = NIL;
 
    indexpr_item = list_head(indexprs);
 
    context = deparse_context_for(get_relation_name(indrelid), indrelid);
 
    /*
     * Start the index definition.  Note that the index's name should never be
     * schema-qualified, but the indexed rel's name may be.
     */
    initStringInfo(&buf);
 
    if (!attrsOnly)
    {
        if (!isConstraint)
            appendStringInfo(&buf, "CREATE %sINDEX %s ON %s%s USING %s (",
                             idxrec->indisunique ? "UNIQUE " : "",
                             quote_identifier(NameStr(idxrelrec->relname)),
                             idxrelrec->relkind == RELKIND_PARTITIONED_INDEX
                             && !inherits ? "ONLY " : "",
                             (prettyFlags & PRETTYFLAG_SCHEMA) ?
                             generate_relation_name(indrelid, NIL) :
                             generate_qualified_relation_name(indrelid),
                             quote_identifier(NameStr(amrec->amname)));
        else                    /* currently, must be EXCLUDE constraint */
            appendStringInfo(&buf, "EXCLUDE USING %s (",
                             quote_identifier(NameStr(amrec->amname)));
    }
 
    /*
     * Report the indexed attributes
     */
    sep = "";
    for (keyno = 0; keyno < idxrec->indnatts; keyno++)
    {
        AttrNumber  attnum = idxrec->indkey.values[keyno];
        Oid         keycoltype;
        Oid         keycolcollation;
 
        /*
         * Ignore non-key attributes if told to.
         */
        if (keysOnly && keyno >= idxrec->indnkeyatts)
            break;
 
        /* Otherwise, print INCLUDE to divide key and non-key attrs. */
        if (!colno && keyno == idxrec->indnkeyatts)
        {
            appendStringInfoString(&buf, ") INCLUDE (");
            sep = "";
        }
 
        if (!colno)
            appendStringInfoString(&buf, sep);
        sep = ", ";
 
        if (attnum != 0)
        {
            /* Simple index column */
            char       *attname;
            int32       keycoltypmod;
 
            attname = get_attname(indrelid, attnum, false);
            if (!colno || colno == keyno + 1)
                appendStringInfoString(&buf, quote_identifier(attname));
            get_atttypetypmodcoll(indrelid, attnum,
                                  &keycoltype, &keycoltypmod,
                                  &keycolcollation);
        }
        else
        {
            /* expressional index */
            Node       *indexkey;
 
            if (indexpr_item == NULL)
                elog(ERROR, "too few entries in indexprs list");
            indexkey = (Node *) lfirst(indexpr_item);
            indexpr_item = lnext(indexprs, indexpr_item);
            /* Deparse */
            str = deparse_expression_pretty(indexkey, context, false, false,
                                            prettyFlags, 0);
            if (!colno || colno == keyno + 1)
            {
                /* Need parens if it's not a bare function call */
                if (looks_like_function(indexkey))
                    appendStringInfoString(&buf, str);
                else
                    appendStringInfo(&buf, "(%s)", str);
            }
            keycoltype = exprType(indexkey);
            keycolcollation = exprCollation(indexkey);
        }
 
        /* Print additional decoration for (selected) key columns */
        if (!attrsOnly && keyno < idxrec->indnkeyatts &&
            (!colno || colno == keyno + 1))
        {
            int16       opt = indoption->values[keyno];
            Oid         indcoll = indcollation->values[keyno];
            Datum       attoptions = get_attoptions(indexrelid, keyno + 1);
            bool        has_options = attoptions != (Datum) 0;
 
            /* Add collation, if not default for column */
            if (OidIsValid(indcoll) && indcoll != keycolcollation)
                appendStringInfo(&buf, " COLLATE %s",
                                 generate_collation_name((indcoll)));
 
            /* Add the operator class name, if not default */
            get_opclass_name(indclass->values[keyno],
                             has_options ? InvalidOid : keycoltype, &buf);
 
            if (has_options)
            {
                appendStringInfoString(&buf, " (");
                get_reloptions(&buf, attoptions);
                appendStringInfoChar(&buf, ')');
            }
 
            /* Add options if relevant */
            if (amroutine->amcanorder)
            {
                /* if it supports sort ordering, report DESC and NULLS opts */
                if (opt & INDOPTION_DESC)
                {
                    appendStringInfoString(&buf, " DESC");
                    /* NULLS FIRST is the default in this case */
                    if (!(opt & INDOPTION_NULLS_FIRST))
                        appendStringInfoString(&buf, " NULLS LAST");
                }
                else
                {
                    if (opt & INDOPTION_NULLS_FIRST)
                        appendStringInfoString(&buf, " NULLS FIRST");
                }
            }
 
            /* Add the exclusion operator if relevant */
            if (excludeOps != NULL)
                appendStringInfo(&buf, " WITH %s",
                                 generate_operator_name(excludeOps[keyno],
                                                        keycoltype,
                                                        keycoltype));
        }
    }
 
    if (!attrsOnly)
    {
        appendStringInfoChar(&buf, ')');
 
        if (idxrec->indnullsnotdistinct)
            appendStringInfoString(&buf, " NULLS NOT DISTINCT");
 
        /*
         * If it has options, append "WITH (options)"
         */
        str = flatten_reloptions(indexrelid);
        if (str)
        {
            appendStringInfo(&buf, " WITH (%s)", str);
            pfree(str);
        }
 
        /*
         * Print tablespace, but only if requested
         */
        if (showTblSpc)
        {
            Oid         tblspc;
 
            tblspc = get_rel_tablespace(indexrelid);
            if (OidIsValid(tblspc))
            {
                if (isConstraint)
                    appendStringInfoString(&buf, " USING INDEX");
                appendStringInfo(&buf, " TABLESPACE %s",
                                 quote_identifier(get_tablespace_name(tblspc)));
            }
        }
 
        /*
         * If it's a partial index, decompile and append the predicate
         */
        if (!heap_attisnull(ht_idx, Anum_pg_index_indpred, NULL))
        {
            Node       *node;
            Datum       predDatum;
            char       *predString;
 
            /* Convert text string to node tree */
            predDatum = SysCacheGetAttrNotNull(INDEXRELID, ht_idx,
                                               Anum_pg_index_indpred);
            predString = TextDatumGetCString(predDatum);
            node = (Node *) stringToNode(predString);
            pfree(predString);
 
            /* Deparse */
            str = deparse_expression_pretty(node, context, false, false,
                                            prettyFlags, 0);
            if (isConstraint)
                appendStringInfo(&buf, " WHERE (%s)", str);
            else
                appendStringInfo(&buf, " WHERE %s", str);
        }
    }
 
    /* Clean up */
    ReleaseSysCache(ht_idx);
    ReleaseSysCache(ht_idxrel);
    ReleaseSysCache(ht_am);
 
    return buf.data;
}
 
/* ----------
 * pg_get_querydef
 *
 * Public entry point to deparse one query parsetree.
 * The pretty flags are determined by GET_PRETTY_FLAGS(pretty).
 *
 * The result is a palloc'd C string.
 * ----------
 */
char *
pg_get_querydef(Query *query, bool pretty)
{
    StringInfoData buf;
    int         prettyFlags;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    initStringInfo(&buf);
 
    get_query_def(query, &buf, NIL, NULL, true,
                  prettyFlags, WRAP_COLUMN_DEFAULT, 0);
 
    return buf.data;
}
 
/*
 * pg_get_statisticsobjdef
 *      Get the definition of an extended statistics object
 */
Datum
pg_get_statisticsobjdef(PG_FUNCTION_ARGS)
{
    Oid         statextid = PG_GETARG_OID(0);
    char       *res;
 
    res = pg_get_statisticsobj_worker(statextid, false, true);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
/*
 * Internal version for use by ALTER TABLE.
 * Includes a tablespace clause in the result.
 * Returns a palloc'd C string; no pretty-printing.
 */
char *
pg_get_statisticsobjdef_string(Oid statextid)
{
    return pg_get_statisticsobj_worker(statextid, false, false);
}
 
/*
 * pg_get_statisticsobjdef_columns
 *      Get columns and expressions for an extended statistics object
 */
Datum
pg_get_statisticsobjdef_columns(PG_FUNCTION_ARGS)
{
    Oid         statextid = PG_GETARG_OID(0);
    char       *res;
 
    res = pg_get_statisticsobj_worker(statextid, true, true);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
/*
 * Internal workhorse to decompile an extended statistics object.
 */
static char *
pg_get_statisticsobj_worker(Oid statextid, bool columns_only, bool missing_ok)
{
    Form_pg_statistic_ext statextrec;
    HeapTuple   statexttup;
    StringInfoData buf;
    int         colno;
    char       *nsp;
    ArrayType  *arr;
    char       *enabled;
    Datum       datum;
    bool        ndistinct_enabled;
    bool        dependencies_enabled;
    bool        mcv_enabled;
    int         i;
    List       *context;
    ListCell   *lc;
    List       *exprs = NIL;
    bool        has_exprs;
    int         ncolumns;
 
    statexttup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(statextid));
 
    if (!HeapTupleIsValid(statexttup))
    {
        if (missing_ok)
            return NULL;
        elog(ERROR, "cache lookup failed for statistics object %u", statextid);
    }
 
    /* has the statistics expressions? */
    has_exprs = !heap_attisnull(statexttup, Anum_pg_statistic_ext_stxexprs, NULL);
 
    statextrec = (Form_pg_statistic_ext) GETSTRUCT(statexttup);
 
    /*
     * Get the statistics expressions, if any.  (NOTE: we do not use the
     * relcache versions of the expressions, because we want to display
     * non-const-folded expressions.)
     */
    if (has_exprs)
    {
        Datum       exprsDatum;
        char       *exprsString;
 
        exprsDatum = SysCacheGetAttrNotNull(STATEXTOID, statexttup,
                                            Anum_pg_statistic_ext_stxexprs);
        exprsString = TextDatumGetCString(exprsDatum);
        exprs = (List *) stringToNode(exprsString);
        pfree(exprsString);
    }
    else
        exprs = NIL;
 
    /* count the number of columns (attributes and expressions) */
    ncolumns = statextrec->stxkeys.dim1 + list_length(exprs);
 
    initStringInfo(&buf);
 
    if (!columns_only)
    {
        nsp = get_namespace_name_or_temp(statextrec->stxnamespace);
        appendStringInfo(&buf, "CREATE STATISTICS %s",
                         quote_qualified_identifier(nsp,
                                                    NameStr(statextrec->stxname)));
 
        /*
         * Decode the stxkind column so that we know which stats types to
         * print.
         */
        datum = SysCacheGetAttrNotNull(STATEXTOID, statexttup,
                                       Anum_pg_statistic_ext_stxkind);
        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);
 
        ndistinct_enabled = false;
        dependencies_enabled = false;
        mcv_enabled = false;
 
        for (i = 0; i < ARR_DIMS(arr)[0]; i++)
        {
            if (enabled[i] == STATS_EXT_NDISTINCT)
                ndistinct_enabled = true;
            else if (enabled[i] == STATS_EXT_DEPENDENCIES)
                dependencies_enabled = true;
            else if (enabled[i] == STATS_EXT_MCV)
                mcv_enabled = true;
 
            /* ignore STATS_EXT_EXPRESSIONS (it's built automatically) */
        }
 
        /*
         * If any option is disabled, then we'll need to append the types
         * clause to show which options are enabled.  We omit the types clause
         * on purpose when all options are enabled, so a pg_dump/pg_restore
         * will create all statistics types on a newer postgres version, if
         * the statistics had all options enabled on the original version.
         *
         * But if the statistics is defined on just a single column, it has to
         * be an expression statistics. In that case we don't need to specify
         * kinds.
         */
        if ((!ndistinct_enabled || !dependencies_enabled || !mcv_enabled) &&
            (ncolumns > 1))
        {
            bool        gotone = false;
 
            appendStringInfoString(&buf, " (");
 
            if (ndistinct_enabled)
            {
                appendStringInfoString(&buf, "ndistinct");
                gotone = true;
            }
 
            if (dependencies_enabled)
            {
                appendStringInfo(&buf, "%sdependencies", gotone ? ", " : "");
                gotone = true;
            }
 
            if (mcv_enabled)
                appendStringInfo(&buf, "%smcv", gotone ? ", " : "");
 
            appendStringInfoChar(&buf, ')');
        }
 
        appendStringInfoString(&buf, " ON ");
    }
 
    /* decode simple column references */
    for (colno = 0; colno < statextrec->stxkeys.dim1; colno++)
    {
        AttrNumber  attnum = statextrec->stxkeys.values[colno];
        char       *attname;
 
        if (colno > 0)
            appendStringInfoString(&buf, ", ");
 
        attname = get_attname(statextrec->stxrelid, attnum, false);
 
        appendStringInfoString(&buf, quote_identifier(attname));
    }
 
    context = deparse_context_for(get_relation_name(statextrec->stxrelid),
                                  statextrec->stxrelid);
 
    foreach(lc, exprs)
    {
        Node       *expr = (Node *) lfirst(lc);
        char       *str;
        int         prettyFlags = PRETTYFLAG_PAREN;
 
        str = deparse_expression_pretty(expr, context, false, false,
                                        prettyFlags, 0);
 
        if (colno > 0)
            appendStringInfoString(&buf, ", ");
 
        /* Need parens if it's not a bare function call */
        if (looks_like_function(expr))
            appendStringInfoString(&buf, str);
        else
            appendStringInfo(&buf, "(%s)", str);
 
        colno++;
    }
 
    if (!columns_only)
        appendStringInfo(&buf, " FROM %s",
                         generate_relation_name(statextrec->stxrelid, NIL));
 
    ReleaseSysCache(statexttup);
 
    return buf.data;
}
 
/*
 * Generate text array of expressions for statistics object.
 */
Datum
pg_get_statisticsobjdef_expressions(PG_FUNCTION_ARGS)
{
    Oid         statextid = PG_GETARG_OID(0);
    Form_pg_statistic_ext statextrec;
    HeapTuple   statexttup;
    Datum       datum;
    List       *context;
    ListCell   *lc;
    List       *exprs = NIL;
    bool        has_exprs;
    char       *tmp;
    ArrayBuildState *astate = NULL;
 
    statexttup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(statextid));
 
    if (!HeapTupleIsValid(statexttup))
        PG_RETURN_NULL();
 
    /* Does the stats object have expressions? */
    has_exprs = !heap_attisnull(statexttup, Anum_pg_statistic_ext_stxexprs, NULL);
 
    /* no expressions? we're done */
    if (!has_exprs)
    {
        ReleaseSysCache(statexttup);
        PG_RETURN_NULL();
    }
 
    statextrec = (Form_pg_statistic_ext) GETSTRUCT(statexttup);
 
    /*
     * Get the statistics expressions, and deparse them into text values.
     */
    datum = SysCacheGetAttrNotNull(STATEXTOID, statexttup,
                                   Anum_pg_statistic_ext_stxexprs);
    tmp = TextDatumGetCString(datum);
    exprs = (List *) stringToNode(tmp);
    pfree(tmp);
 
    context = deparse_context_for(get_relation_name(statextrec->stxrelid),
                                  statextrec->stxrelid);
 
    foreach(lc, exprs)
    {
        Node       *expr = (Node *) lfirst(lc);
        char       *str;
        int         prettyFlags = PRETTYFLAG_INDENT;
 
        str = deparse_expression_pretty(expr, context, false, false,
                                        prettyFlags, 0);
 
        astate = accumArrayResult(astate,
                                  PointerGetDatum(cstring_to_text(str)),
                                  false,
                                  TEXTOID,
                                  CurrentMemoryContext);
    }
 
    ReleaseSysCache(statexttup);
 
    PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));
}
 
/*
 * pg_get_partkeydef
 *
 * Returns the partition key specification, ie, the following:
 *
 * { RANGE | LIST | HASH } (column opt_collation opt_opclass [, ...])
 */
Datum
pg_get_partkeydef(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    char       *res;
 
    res = pg_get_partkeydef_worker(relid, PRETTYFLAG_INDENT, false, true);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
/* Internal version that just reports the column definitions */
char *
pg_get_partkeydef_columns(Oid relid, bool pretty)
{
    int         prettyFlags;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    return pg_get_partkeydef_worker(relid, prettyFlags, true, false);
}
 
/*
 * Internal workhorse to decompile a partition key definition.
 */
static char *
pg_get_partkeydef_worker(Oid relid, int prettyFlags,
                         bool attrsOnly, bool missing_ok)
{
    Form_pg_partitioned_table form;
    HeapTuple   tuple;
    oidvector  *partclass;
    oidvector  *partcollation;
    List       *partexprs;
    ListCell   *partexpr_item;
    List       *context;
    Datum       datum;
    StringInfoData buf;
    int         keyno;
    char       *str;
    char       *sep;
 
    tuple = SearchSysCache1(PARTRELID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tuple))
    {
        if (missing_ok)
            return NULL;
        elog(ERROR, "cache lookup failed for partition key of %u", relid);
    }
 
    form = (Form_pg_partitioned_table) GETSTRUCT(tuple);
 
    Assert(form->partrelid == relid);
 
    /* Must get partclass and partcollation the hard way */
    datum = SysCacheGetAttrNotNull(PARTRELID, tuple,
                                   Anum_pg_partitioned_table_partclass);
    partclass = (oidvector *) DatumGetPointer(datum);
 
    datum = SysCacheGetAttrNotNull(PARTRELID, tuple,
                                   Anum_pg_partitioned_table_partcollation);
    partcollation = (oidvector *) DatumGetPointer(datum);
 
 
    /*
     * Get the expressions, if any.  (NOTE: we do not use the relcache
     * versions of the expressions, because we want to display
     * non-const-folded expressions.)
     */
    if (!heap_attisnull(tuple, Anum_pg_partitioned_table_partexprs, NULL))
    {
        Datum       exprsDatum;
        char       *exprsString;
 
        exprsDatum = SysCacheGetAttrNotNull(PARTRELID, tuple,
                                            Anum_pg_partitioned_table_partexprs);
        exprsString = TextDatumGetCString(exprsDatum);
        partexprs = (List *) stringToNode(exprsString);
 
        if (!IsA(partexprs, List))
            elog(ERROR, "unexpected node type found in partexprs: %d",
                 (int) nodeTag(partexprs));
 
        pfree(exprsString);
    }
    else
        partexprs = NIL;
 
    partexpr_item = list_head(partexprs);
    context = deparse_context_for(get_relation_name(relid), relid);
 
    initStringInfo(&buf);
 
    switch (form->partstrat)
    {
        case PARTITION_STRATEGY_HASH:
            if (!attrsOnly)
                appendStringInfoString(&buf, "HASH");
            break;
        case PARTITION_STRATEGY_LIST:
            if (!attrsOnly)
                appendStringInfoString(&buf, "LIST");
            break;
        case PARTITION_STRATEGY_RANGE:
            if (!attrsOnly)
                appendStringInfoString(&buf, "RANGE");
            break;
        default:
            elog(ERROR, "unexpected partition strategy: %d",
                 (int) form->partstrat);
    }
 
    if (!attrsOnly)
        appendStringInfoString(&buf, " (");
    sep = "";
    for (keyno = 0; keyno < form->partnatts; keyno++)
    {
        AttrNumber  attnum = form->partattrs.values[keyno];
        Oid         keycoltype;
        Oid         keycolcollation;
        Oid         partcoll;
 
        appendStringInfoString(&buf, sep);
        sep = ", ";
        if (attnum != 0)
        {
            /* Simple attribute reference */
            char       *attname;
            int32       keycoltypmod;
 
            attname = get_attname(relid, attnum, false);
            appendStringInfoString(&buf, quote_identifier(attname));
            get_atttypetypmodcoll(relid, attnum,
                                  &keycoltype, &keycoltypmod,
                                  &keycolcollation);
        }
        else
        {
            /* Expression */
            Node       *partkey;
 
            if (partexpr_item == NULL)
                elog(ERROR, "too few entries in partexprs list");
            partkey = (Node *) lfirst(partexpr_item);
            partexpr_item = lnext(partexprs, partexpr_item);
 
            /* Deparse */
            str = deparse_expression_pretty(partkey, context, false, false,
                                            prettyFlags, 0);
            /* Need parens if it's not a bare function call */
            if (looks_like_function(partkey))
                appendStringInfoString(&buf, str);
            else
                appendStringInfo(&buf, "(%s)", str);
 
            keycoltype = exprType(partkey);
            keycolcollation = exprCollation(partkey);
        }
 
        /* Add collation, if not default for column */
        partcoll = partcollation->values[keyno];
        if (!attrsOnly && OidIsValid(partcoll) && partcoll != keycolcollation)
            appendStringInfo(&buf, " COLLATE %s",
                             generate_collation_name((partcoll)));
 
        /* Add the operator class name, if not default */
        if (!attrsOnly)
            get_opclass_name(partclass->values[keyno], keycoltype, &buf);
    }
 
    if (!attrsOnly)
        appendStringInfoChar(&buf, ')');
 
    /* Clean up */
    ReleaseSysCache(tuple);
 
    return buf.data;
}
 
/*
 * pg_get_partition_constraintdef
 *
 * Returns partition constraint expression as a string for the input relation
 */
Datum
pg_get_partition_constraintdef(PG_FUNCTION_ARGS)
{
    Oid         relationId = PG_GETARG_OID(0);
    Expr       *constr_expr;
    int         prettyFlags;
    List       *context;
    char       *consrc;
 
    constr_expr = get_partition_qual_relid(relationId);
 
    /* Quick exit if no partition constraint */
    if (constr_expr == NULL)
        PG_RETURN_NULL();
 
    /*
     * Deparse and return the constraint expression.
     */
    prettyFlags = PRETTYFLAG_INDENT;
    context = deparse_context_for(get_relation_name(relationId), relationId);
    consrc = deparse_expression_pretty((Node *) constr_expr, context, false,
                                       false, prettyFlags, 0);
 
    PG_RETURN_TEXT_P(string_to_text(consrc));
}
 
/*
 * pg_get_partconstrdef_string
 *
 * Returns the partition constraint as a C-string for the input relation, with
 * the given alias.  No pretty-printing.
 */
char *
pg_get_partconstrdef_string(Oid partitionId, char *aliasname)
{
    Expr       *constr_expr;
    List       *context;
 
    constr_expr = get_partition_qual_relid(partitionId);
    context = deparse_context_for(aliasname, partitionId);
 
    return deparse_expression((Node *) constr_expr, context, true, false);
}
 
/*
 * pg_get_constraintdef
 *
 * Returns the definition for the constraint, ie, everything that needs to
 * appear after "ALTER TABLE ... ADD CONSTRAINT <constraintname>".
 */
Datum
pg_get_constraintdef(PG_FUNCTION_ARGS)
{
    Oid         constraintId = PG_GETARG_OID(0);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = PRETTYFLAG_INDENT;
 
    res = pg_get_constraintdef_worker(constraintId, false, prettyFlags, true);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
Datum
pg_get_constraintdef_ext(PG_FUNCTION_ARGS)
{
    Oid         constraintId = PG_GETARG_OID(0);
    bool        pretty = PG_GETARG_BOOL(1);
    int         prettyFlags;
    char       *res;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    res = pg_get_constraintdef_worker(constraintId, false, prettyFlags, true);
 
    if (res == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_TEXT_P(string_to_text(res));
}
 
/*
 * Internal version that returns a full ALTER TABLE ... ADD CONSTRAINT command
 */
char *
pg_get_constraintdef_command(Oid constraintId)
{
    return pg_get_constraintdef_worker(constraintId, true, 0, false);
}
 
/*
 * As of 9.4, we now use an MVCC snapshot for this.
 */
static char *
pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
                            int prettyFlags, bool missing_ok)
{
    HeapTuple   tup;
    Form_pg_constraint conForm;
    StringInfoData buf;
    SysScanDesc scandesc;
    ScanKeyData scankey[1];
    Snapshot    snapshot = RegisterSnapshot(GetTransactionSnapshot());
    Relation    relation = table_open(ConstraintRelationId, AccessShareLock);
 
    ScanKeyInit(&scankey[0],
                Anum_pg_constraint_oid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(constraintId));
 
    scandesc = systable_beginscan(relation,
                                  ConstraintOidIndexId,
                                  true,
                                  snapshot,
                                  1,
                                  scankey);
 
    /*
     * We later use the tuple with SysCacheGetAttr() as if we had obtained it
     * via SearchSysCache, which works fine.
     */
    tup = systable_getnext(scandesc);
 
    UnregisterSnapshot(snapshot);
 
    if (!HeapTupleIsValid(tup))
    {
        if (missing_ok)
        {
            systable_endscan(scandesc);
            table_close(relation, AccessShareLock);
            return NULL;
        }
        elog(ERROR, "could not find tuple for constraint %u", constraintId);
    }
 
    conForm = (Form_pg_constraint) GETSTRUCT(tup);
 
    initStringInfo(&buf);
 
    if (fullCommand)
    {
        if (OidIsValid(conForm->conrelid))
        {
            /*
             * Currently, callers want ALTER TABLE (without ONLY) for CHECK
             * constraints, and other types of constraints don't inherit
             * anyway so it doesn't matter whether we say ONLY or not. Someday
             * we might need to let callers specify whether to put ONLY in the
             * command.
             */
            appendStringInfo(&buf, "ALTER TABLE %s ADD CONSTRAINT %s ",
                             generate_qualified_relation_name(conForm->conrelid),
                             quote_identifier(NameStr(conForm->conname)));
        }
        else
        {
            /* Must be a domain constraint */
            Assert(OidIsValid(conForm->contypid));
            appendStringInfo(&buf, "ALTER DOMAIN %s ADD CONSTRAINT %s ",
                             generate_qualified_type_name(conForm->contypid),
                             quote_identifier(NameStr(conForm->conname)));
        }
    }
 
    switch (conForm->contype)
    {
        case CONSTRAINT_FOREIGN:
            {
                Datum       val;
                bool        isnull;
                const char *string;
 
                /* Start off the constraint definition */
                appendStringInfoString(&buf, "FOREIGN KEY (");
 
                /* Fetch and build referencing-column list */
                val = SysCacheGetAttrNotNull(CONSTROID, tup,
                                             Anum_pg_constraint_conkey);
 
                /* If it is a temporal foreign key then it uses PERIOD. */
                decompile_column_index_array(val, conForm->conrelid, conForm->conperiod, &buf);
 
                /* add foreign relation name */
                appendStringInfo(&buf, ") REFERENCES %s(",
                                 generate_relation_name(conForm->confrelid,
                                                        NIL));
 
                /* Fetch and build referenced-column list */
                val = SysCacheGetAttrNotNull(CONSTROID, tup,
                                             Anum_pg_constraint_confkey);
 
                decompile_column_index_array(val, conForm->confrelid, conForm->conperiod, &buf);
 
                appendStringInfoChar(&buf, ')');
 
                /* Add match type */
                switch (conForm->confmatchtype)
                {
                    case FKCONSTR_MATCH_FULL:
                        string = " MATCH FULL";
                        break;
                    case FKCONSTR_MATCH_PARTIAL:
                        string = " MATCH PARTIAL";
                        break;
                    case FKCONSTR_MATCH_SIMPLE:
                        string = "";
                        break;
                    default:
                        elog(ERROR, "unrecognized confmatchtype: %d",
                             conForm->confmatchtype);
                        string = "";    /* keep compiler quiet */
                        break;
                }
                appendStringInfoString(&buf, string);
 
                /* Add ON UPDATE and ON DELETE clauses, if needed */
                switch (conForm->confupdtype)
                {
                    case FKCONSTR_ACTION_NOACTION:
                        string = NULL;  /* suppress default */
                        break;
                    case FKCONSTR_ACTION_RESTRICT:
                        string = "RESTRICT";
                        break;
                    case FKCONSTR_ACTION_CASCADE:
                        string = "CASCADE";
                        break;
                    case FKCONSTR_ACTION_SETNULL:
                        string = "SET NULL";
                        break;
                    case FKCONSTR_ACTION_SETDEFAULT:
                        string = "SET DEFAULT";
                        break;
                    default:
                        elog(ERROR, "unrecognized confupdtype: %d",
                             conForm->confupdtype);
                        string = NULL;  /* keep compiler quiet */
                        break;
                }
                if (string)
                    appendStringInfo(&buf, " ON UPDATE %s", string);
 
                switch (conForm->confdeltype)
                {
                    case FKCONSTR_ACTION_NOACTION:
                        string = NULL;  /* suppress default */
                        break;
                    case FKCONSTR_ACTION_RESTRICT:
                        string = "RESTRICT";
                        break;
                    case FKCONSTR_ACTION_CASCADE:
                        string = "CASCADE";
                        break;
                    case FKCONSTR_ACTION_SETNULL:
                        string = "SET NULL";
                        break;
                    case FKCONSTR_ACTION_SETDEFAULT:
                        string = "SET DEFAULT";
                        break;
                    default:
                        elog(ERROR, "unrecognized confdeltype: %d",
                             conForm->confdeltype);
                        string = NULL;  /* keep compiler quiet */
                        break;
                }
                if (string)
                    appendStringInfo(&buf, " ON DELETE %s", string);
 
                /*
                 * Add columns specified to SET NULL or SET DEFAULT if
                 * provided.
                 */
                val = SysCacheGetAttr(CONSTROID, tup,
                                      Anum_pg_constraint_confdelsetcols, &isnull);
                if (!isnull)
                {
                    appendStringInfoString(&buf, " (");
                    decompile_column_index_array(val, conForm->conrelid, false, &buf);
                    appendStringInfoChar(&buf, ')');
                }
 
                break;
            }
        case CONSTRAINT_PRIMARY:
        case CONSTRAINT_UNIQUE:
            {
                Datum       val;
                Oid         indexId;
                int         keyatts;
                HeapTuple   indtup;
 
                /* Start off the constraint definition */
                if (conForm->contype == CONSTRAINT_PRIMARY)
                    appendStringInfoString(&buf, "PRIMARY KEY ");
                else
                    appendStringInfoString(&buf, "UNIQUE ");
 
                indexId = conForm->conindid;
 
                indtup = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexId));
                if (!HeapTupleIsValid(indtup))
                    elog(ERROR, "cache lookup failed for index %u", indexId);
                if (conForm->contype == CONSTRAINT_UNIQUE &&
                    ((Form_pg_index) GETSTRUCT(indtup))->indnullsnotdistinct)
                    appendStringInfoString(&buf, "NULLS NOT DISTINCT ");
 
                appendStringInfoChar(&buf, '(');
 
                /* Fetch and build target column list */
                val = SysCacheGetAttrNotNull(CONSTROID, tup,
                                             Anum_pg_constraint_conkey);
 
                keyatts = decompile_column_index_array(val, conForm->conrelid, false, &buf);
                if (conForm->conperiod)
                    appendStringInfoString(&buf, " WITHOUT OVERLAPS");
 
                appendStringInfoChar(&buf, ')');
 
                /* Build including column list (from pg_index.indkeys) */
                val = SysCacheGetAttrNotNull(INDEXRELID, indtup,
                                             Anum_pg_index_indnatts);
                if (DatumGetInt32(val) > keyatts)
                {
                    Datum       cols;
                    Datum      *keys;
                    int         nKeys;
                    int         j;
 
                    appendStringInfoString(&buf, " INCLUDE (");
 
                    cols = SysCacheGetAttrNotNull(INDEXRELID, indtup,
                                                  Anum_pg_index_indkey);
 
                    deconstruct_array_builtin(DatumGetArrayTypeP(cols), INT2OID,
                                              &keys, NULL, &nKeys);
 
                    for (j = keyatts; j < nKeys; j++)
                    {
                        char       *colName;
 
                        colName = get_attname(conForm->conrelid,
                                              DatumGetInt16(keys[j]), false);
                        if (j > keyatts)
                            appendStringInfoString(&buf, ", ");
                        appendStringInfoString(&buf, quote_identifier(colName));
                    }
 
                    appendStringInfoChar(&buf, ')');
                }
                ReleaseSysCache(indtup);
 
                /* XXX why do we only print these bits if fullCommand? */
                if (fullCommand && OidIsValid(indexId))
                {
                    char       *options = flatten_reloptions(indexId);
                    Oid         tblspc;
 
                    if (options)
                    {
                        appendStringInfo(&buf, " WITH (%s)", options);
                        pfree(options);
                    }
 
                    /*
                     * Print the tablespace, unless it's the database default.
                     * This is to help ALTER TABLE usage of this facility,
                     * which needs this behavior to recreate exact catalog
                     * state.
                     */
                    tblspc = get_rel_tablespace(indexId);
                    if (OidIsValid(tblspc))
                        appendStringInfo(&buf, " USING INDEX TABLESPACE %s",
                                         quote_identifier(get_tablespace_name(tblspc)));
                }
 
                break;
            }
        case CONSTRAINT_CHECK:
            {
                Datum       val;
                char       *conbin;
                char       *consrc;
                Node       *expr;
                List       *context;
 
                /* Fetch constraint expression in parsetree form */
                val = SysCacheGetAttrNotNull(CONSTROID, tup,
                                             Anum_pg_constraint_conbin);
 
                conbin = TextDatumGetCString(val);
                expr = stringToNode(conbin);
 
                /* Set up deparsing context for Var nodes in constraint */
                if (conForm->conrelid != InvalidOid)
                {
                    /* relation constraint */
                    context = deparse_context_for(get_relation_name(conForm->conrelid),
                                                  conForm->conrelid);
                }
                else
                {
                    /* domain constraint --- can't have Vars */
                    context = NIL;
                }
 
                consrc = deparse_expression_pretty(expr, context, false, false,
                                                   prettyFlags, 0);
 
                /*
                 * Now emit the constraint definition, adding NO INHERIT if
                 * necessary.
                 *
                 * There are cases where the constraint expression will be
                 * fully parenthesized and we don't need the outer parens ...
                 * but there are other cases where we do need 'em.  Be
                 * conservative for now.
                 *
                 * Note that simply checking for leading '(' and trailing ')'
                 * would NOT be good enough, consider "(x > 0) AND (y > 0)".
                 */
                appendStringInfo(&buf, "CHECK (%s)%s",
                                 consrc,
                                 conForm->connoinherit ? " NO INHERIT" : "");
                break;
            }
        case CONSTRAINT_NOTNULL:
            {
                if (conForm->conrelid)
                {
                    AttrNumber  attnum;
 
                    attnum = extractNotNullColumn(tup);
 
                    appendStringInfo(&buf, "NOT NULL %s",
                                     quote_identifier(get_attname(conForm->conrelid,
                                                                  attnum, false)));
                    if (((Form_pg_constraint) GETSTRUCT(tup))->connoinherit)
                        appendStringInfoString(&buf, " NO INHERIT");
                }
                else if (conForm->contypid)
                {
                    /* conkey is null for domain not-null constraints */
                    appendStringInfoString(&buf, "NOT NULL");
                }
                break;
            }
 
        case CONSTRAINT_TRIGGER:
 
            /*
             * There isn't an ALTER TABLE syntax for creating a user-defined
             * constraint trigger, but it seems better to print something than
             * throw an error; if we throw error then this function couldn't
             * safely be applied to all rows of pg_constraint.
             */
            appendStringInfoString(&buf, "TRIGGER");
            break;
        case CONSTRAINT_EXCLUSION:
            {
                Oid         indexOid = conForm->conindid;
                Datum       val;
                Datum      *elems;
                int         nElems;
                int         i;
                Oid        *operators;
 
                /* Extract operator OIDs from the pg_constraint tuple */
                val = SysCacheGetAttrNotNull(CONSTROID, tup,
                                             Anum_pg_constraint_conexclop);
 
                deconstruct_array_builtin(DatumGetArrayTypeP(val), OIDOID,
                                          &elems, NULL, &nElems);
 
                operators = (Oid *) palloc(nElems * sizeof(Oid));
                for (i = 0; i < nElems; i++)
                    operators[i] = DatumGetObjectId(elems[i]);
 
                /* pg_get_indexdef_worker does the rest */
                /* suppress tablespace because pg_dump wants it that way */
                appendStringInfoString(&buf,
                                       pg_get_indexdef_worker(indexOid,
                                                              0,
                                                              operators,
                                                              false,
                                                              false,
                                                              false,
                                                              false,
                                                              prettyFlags,
                                                              false));
                break;
            }
        default:
            elog(ERROR, "invalid constraint type \"%c\"", conForm->contype);
            break;
    }
 
    if (conForm->condeferrable)
        appendStringInfoString(&buf, " DEFERRABLE");
    if (conForm->condeferred)
        appendStringInfoString(&buf, " INITIALLY DEFERRED");
 
    /* Validated status is irrelevant when the constraint is NOT ENFORCED. */
    if (!conForm->conenforced)
        appendStringInfoString(&buf, " NOT ENFORCED");
    else if (!conForm->convalidated)
        appendStringInfoString(&buf, " NOT VALID");
 
    /* Cleanup */
    systable_endscan(scandesc);
    table_close(relation, AccessShareLock);
 
    return buf.data;
}
 
 
/*
 * Convert an int16[] Datum into a comma-separated list of column names
 * for the indicated relation; append the list to buf.  Returns the number
 * of keys.
 */
static int
decompile_column_index_array(Datum column_index_array, Oid relId,
                             bool withPeriod, StringInfo buf)
{
    Datum      *keys;
    int         nKeys;
    int         j;
 
    /* Extract data from array of int16 */
    deconstruct_array_builtin(DatumGetArrayTypeP(column_index_array), INT2OID,
                              &keys, NULL, &nKeys);
 
    for (j = 0; j < nKeys; j++)
    {
        char       *colName;
 
        colName = get_attname(relId, DatumGetInt16(keys[j]), false);
 
        if (j == 0)
            appendStringInfoString(buf, quote_identifier(colName));
        else
            appendStringInfo(buf, ", %s%s",
                             (withPeriod && j == nKeys - 1) ? "PERIOD " : "",
                             quote_identifier(colName));
    }
 
    return nKeys;
}
 
 
/* ----------
 * pg_get_expr          - Decompile an expression tree
 *
 * Input: an expression tree in nodeToString form, and a relation OID
 *
 * Output: reverse-listed expression
 *
 * Currently, the expression can only refer to a single relation, namely
 * the one specified by the second parameter.  This is sufficient for
 * partial indexes, column default expressions, etc.  We also support
 * Var-free expressions, for which the OID can be InvalidOid.
 *
 * If the OID is nonzero but not actually valid, don't throw an error,
 * just return NULL.  This is a bit questionable, but it's what we've
 * done historically, and it can help avoid unwanted failures when
 * examining catalog entries for just-deleted relations.
 *
 * We expect this function to work, or throw a reasonably clean error,
 * for any node tree that can appear in a catalog pg_node_tree column.
 * Query trees, such as those appearing in pg_rewrite.ev_action, are
 * not supported.  Nor are expressions in more than one relation, which
 * can appear in places like pg_rewrite.ev_qual.
 * ----------
 */
Datum
pg_get_expr(PG_FUNCTION_ARGS)
{
    text       *expr = PG_GETARG_TEXT_PP(0);
    Oid         relid = PG_GETARG_OID(1);
    text       *result;
    int         prettyFlags;
 
    prettyFlags = PRETTYFLAG_INDENT;
 
    result = pg_get_expr_worker(expr, relid, prettyFlags);
    if (result)
        PG_RETURN_TEXT_P(result);
    else
        PG_RETURN_NULL();
}
 
Datum
pg_get_expr_ext(PG_FUNCTION_ARGS)
{
    text       *expr = PG_GETARG_TEXT_PP(0);
    Oid         relid = PG_GETARG_OID(1);
    bool        pretty = PG_GETARG_BOOL(2);
    text       *result;
    int         prettyFlags;
 
    prettyFlags = GET_PRETTY_FLAGS(pretty);
 
    result = pg_get_expr_worker(expr, relid, prettyFlags);
    if (result)
        PG_RETURN_TEXT_P(result);
    else
        PG_RETURN_NULL();
}
 
static text *
pg_get_expr_worker(text *expr, Oid relid, int prettyFlags)
{
    Node       *node;
    Node       *tst;
    Relids      relids;
    List       *context;
    char       *exprstr;
    Relation    rel = NULL;
    char       *str;
 
    /* Convert input pg_node_tree (really TEXT) object to C string */
    exprstr = text_to_cstring(expr);
 
    /* Convert expression to node tree */
    node = (Node *) stringToNode(exprstr);
 
    pfree(exprstr);
 
    /*
     * Throw error if the input is a querytree rather than an expression tree.
     * While we could support queries here, there seems no very good reason
     * to.  In most such catalog columns, we'll see a List of Query nodes, or
     * even nested Lists, so drill down to a non-List node before checking.
     */
    tst = node;
    while (tst && IsA(tst, List))
        tst = linitial((List *) tst);
    if (tst && IsA(tst, Query))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("input is a query, not an expression")));
 
    /*
     * Throw error if the expression contains Vars we won't be able to
     * deparse.
     */
    relids = pull_varnos(NULL, node);
    if (OidIsValid(relid))
    {
        if (!bms_is_subset(relids, bms_make_singleton(1)))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("expression contains variables of more than one relation")));
    }
    else
    {
        if (!bms_is_empty(relids))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("expression contains variables")));
    }
 
    /*
     * Prepare deparse context if needed.  If we are deparsing with a relid,
     * we need to transiently open and lock the rel, to make sure it won't go
     * away underneath us.  (set_relation_column_names would lock it anyway,
     * so this isn't really introducing any new behavior.)
     */
    if (OidIsValid(relid))
    {
        rel = try_relation_open(relid, AccessShareLock);
        if (rel == NULL)
            return NULL;
        context = deparse_context_for(RelationGetRelationName(rel), relid);
    }
    else
        context = NIL;
 
    /* Deparse */
    str = deparse_expression_pretty(node, context, false, false,
                                    prettyFlags, 0);
 
    if (rel != NULL)
        relation_close(rel, AccessShareLock);
 
    return string_to_text(str);
}
 
 
/* ----------
 * pg_get_userbyid      - Get a user name by roleid and
 *                fallback to 'unknown (OID=n)'
 * ----------
 */
Datum
pg_get_userbyid(PG_FUNCTION_ARGS)
{
    Oid         roleid = PG_GETARG_OID(0);
    Name        result;
    HeapTuple   roletup;
    Form_pg_authid role_rec;
 
    /*
     * Allocate space for the result
     */
    result = (Name) palloc(NAMEDATALEN);
    memset(NameStr(*result), 0, NAMEDATALEN);
 
    /*
     * Get the pg_authid entry and print the result
     */
    roletup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
    if (HeapTupleIsValid(roletup))
    {
        role_rec = (Form_pg_authid) GETSTRUCT(roletup);
        *result = role_rec->rolname;
        ReleaseSysCache(roletup);
    }
    else
        sprintf(NameStr(*result), "unknown (OID=%u)", roleid);
 
    PG_RETURN_NAME(result);
}
 
 
/*
 * pg_get_serial_sequence
 *      Get the name of the sequence used by an identity or serial column,
 *      formatted suitably for passing to setval, nextval or currval.
 *      First parameter is not treated as double-quoted, second parameter
 *      is --- see documentation for reason.
 */
Datum
pg_get_serial_sequence(PG_FUNCTION_ARGS)
{
    text       *tablename = PG_GETARG_TEXT_PP(0);
    text       *columnname = PG_GETARG_TEXT_PP(1);
    RangeVar   *tablerv;
    Oid         tableOid;
    char       *column;
    AttrNumber  attnum;
    Oid         sequenceId = InvalidOid;
    Relation    depRel;
    ScanKeyData key[3];
    SysScanDesc scan;
    HeapTuple   tup;
 
    /* Look up table name.  Can't lock it - we might not have privileges. */
    tablerv = makeRangeVarFromNameList(textToQualifiedNameList(tablename));
    tableOid = RangeVarGetRelid(tablerv, NoLock, false);
 
    /* Get the number of the column */
    column = text_to_cstring(columnname);
 
    attnum = get_attnum(tableOid, column);
    if (attnum == InvalidAttrNumber)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("column \"%s\" of relation \"%s\" does not exist",
                        column, tablerv->relname)));
 
    /* Search the dependency table for the dependent sequence */
    depRel = table_open(DependRelationId, AccessShareLock);
 
    ScanKeyInit(&key[0],
                Anum_pg_depend_refclassid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationRelationId));
    ScanKeyInit(&key[1],
                Anum_pg_depend_refobjid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(tableOid));
    ScanKeyInit(&key[2],
                Anum_pg_depend_refobjsubid,
                BTEqualStrategyNumber, F_INT4EQ,
                Int32GetDatum(attnum));
 
    scan = systable_beginscan(depRel, DependReferenceIndexId, true,
                              NULL, 3, key);
 
    while (HeapTupleIsValid(tup = systable_getnext(scan)))
    {
        Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(tup);
 
        /*
         * Look for an auto dependency (serial column) or internal dependency
         * (identity column) of a sequence on a column.  (We need the relkind
         * test because indexes can also have auto dependencies on columns.)
         */
        if (deprec->classid == RelationRelationId &&
            deprec->objsubid == 0 &&
            (deprec->deptype == DEPENDENCY_AUTO ||
             deprec->deptype == DEPENDENCY_INTERNAL) &&
            get_rel_relkind(deprec->objid) == RELKIND_SEQUENCE)
        {
            sequenceId = deprec->objid;
            break;
        }
    }
 
    systable_endscan(scan);
    table_close(depRel, AccessShareLock);
 
    if (OidIsValid(sequenceId))
    {
        char       *result;
 
        result = generate_qualified_relation_name(sequenceId);
 
        PG_RETURN_TEXT_P(string_to_text(result));
    }
 
    PG_RETURN_NULL();
}
 
 
/*
 * pg_get_functiondef
 *      Returns the complete "CREATE OR REPLACE FUNCTION ..." statement for
 *      the specified function.
 *
 * Note: if you change the output format of this function, be careful not
 * to break psql's rules (in \ef and \sf) for identifying the start of the
 * function body.  To wit: the function body starts on a line that begins with
 * "AS ", "BEGIN ", or "RETURN ", and no preceding line will look like that.
 */
Datum
pg_get_functiondef(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    StringInfoData buf;
    StringInfoData dq;
    HeapTuple   proctup;
    Form_pg_proc proc;
    bool        isfunction;
    Datum       tmp;
    bool        isnull;
    const char *prosrc;
    const char *name;
    const char *nsp;
    float4      procost;
    int         oldlen;
 
    initStringInfo(&buf);
 
    /* Look up the function */
    proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(proctup))
        PG_RETURN_NULL();
 
    proc = (Form_pg_proc) GETSTRUCT(proctup);
    name = NameStr(proc->proname);
 
    if (proc->prokind == PROKIND_AGGREGATE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is an aggregate function", name)));
 
    isfunction = (proc->prokind != PROKIND_PROCEDURE);
 
    /*
     * We always qualify the function name, to ensure the right function gets
     * replaced.
     */
    nsp = get_namespace_name_or_temp(proc->pronamespace);
    appendStringInfo(&buf, "CREATE OR REPLACE %s %s(",
                     isfunction ? "FUNCTION" : "PROCEDURE",
                     quote_qualified_identifier(nsp, name));
    (void) print_function_arguments(&buf, proctup, false, true);
    appendStringInfoString(&buf, ")\n");
    if (isfunction)
    {
        appendStringInfoString(&buf, " RETURNS ");
        print_function_rettype(&buf, proctup);
        appendStringInfoChar(&buf, '\n');
    }
 
    print_function_trftypes(&buf, proctup);
 
    appendStringInfo(&buf, " LANGUAGE %s\n",
                     quote_identifier(get_language_name(proc->prolang, false)));
 
    /* Emit some miscellaneous options on one line */
    oldlen = buf.len;
 
    if (proc->prokind == PROKIND_WINDOW)
        appendStringInfoString(&buf, " WINDOW");
    switch (proc->provolatile)
    {
        case PROVOLATILE_IMMUTABLE:
            appendStringInfoString(&buf, " IMMUTABLE");
            break;
        case PROVOLATILE_STABLE:
            appendStringInfoString(&buf, " STABLE");
            break;
        case PROVOLATILE_VOLATILE:
            break;
    }
 
    switch (proc->proparallel)
    {
        case PROPARALLEL_SAFE:
            appendStringInfoString(&buf, " PARALLEL SAFE");
            break;
        case PROPARALLEL_RESTRICTED:
            appendStringInfoString(&buf, " PARALLEL RESTRICTED");
            break;
        case PROPARALLEL_UNSAFE:
            break;
    }
 
    if (proc->proisstrict)
        appendStringInfoString(&buf, " STRICT");
    if (proc->prosecdef)
        appendStringInfoString(&buf, " SECURITY DEFINER");
    if (proc->proleakproof)
        appendStringInfoString(&buf, " LEAKPROOF");
 
    /* This code for the default cost and rows should match functioncmds.c */
    if (proc->prolang == INTERNALlanguageId ||
        proc->prolang == ClanguageId)
        procost = 1;
    else
        procost = 100;
    if (proc->procost != procost)
        appendStringInfo(&buf, " COST %g", proc->procost);
 
    if (proc->prorows > 0 && proc->prorows != 1000)
        appendStringInfo(&buf, " ROWS %g", proc->prorows);
 
    if (proc->prosupport)
    {
        Oid         argtypes[1];
 
        /*
         * We should qualify the support function's name if it wouldn't be
         * resolved by lookup in the current search path.
         */
        argtypes[0] = INTERNALOID;
        appendStringInfo(&buf, " SUPPORT %s",
                         generate_function_name(proc->prosupport, 1,
                                                NIL, argtypes,
                                                false, NULL, false));
    }
 
    if (oldlen != buf.len)
        appendStringInfoChar(&buf, '\n');
 
    /* Emit any proconfig options, one per line */
    tmp = SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_proconfig, &isnull);
    if (!isnull)
    {
        ArrayType  *a = DatumGetArrayTypeP(tmp);
        int         i;
 
        Assert(ARR_ELEMTYPE(a) == TEXTOID);
        Assert(ARR_NDIM(a) == 1);
        Assert(ARR_LBOUND(a)[0] == 1);
 
        for (i = 1; i <= ARR_DIMS(a)[0]; i++)
        {
            Datum       d;
 
            d = array_ref(a, 1, &i,
                          -1 /* varlenarray */ ,
                          -1 /* TEXT's typlen */ ,
                          false /* TEXT's typbyval */ ,
                          TYPALIGN_INT /* TEXT's typalign */ ,
                          &isnull);
            if (!isnull)
            {
                char       *configitem = TextDatumGetCString(d);
                char       *pos;
 
                pos = strchr(configitem, '=');
                if (pos == NULL)
                    continue;
                *pos++ = '\0';
 
                appendStringInfo(&buf, " SET %s TO ",
                                 quote_identifier(configitem));
 
                /*
                 * Variables that are marked GUC_LIST_QUOTE were already fully
                 * quoted by flatten_set_variable_args() before they were put
                 * into the proconfig array.  However, because the quoting
                 * rules used there aren't exactly like SQL's, we have to
                 * break the list value apart and then quote the elements as
                 * string literals.  (The elements may be double-quoted as-is,
                 * but we can't just feed them to the SQL parser; it would do
                 * the wrong thing with elements that are zero-length or
                 * longer than NAMEDATALEN.)
                 *
                 * Variables that are not so marked should just be emitted as
                 * simple string literals.  If the variable is not known to
                 * guc.c, we'll do that; this makes it unsafe to use
                 * GUC_LIST_QUOTE for extension variables.
                 */
                if (GetConfigOptionFlags(configitem, true) & GUC_LIST_QUOTE)
                {
                    List       *namelist;
                    ListCell   *lc;
 
                    /* Parse string into list of identifiers */
                    if (!SplitGUCList(pos, ',', &namelist))
                    {
                        /* this shouldn't fail really */
                        elog(ERROR, "invalid list syntax in proconfig item");
                    }
                    foreach(lc, namelist)
                    {
                        char       *curname = (char *) lfirst(lc);
 
                        simple_quote_literal(&buf, curname);
                        if (lnext(namelist, lc))
                            appendStringInfoString(&buf, ", ");
                    }
                }
                else
                    simple_quote_literal(&buf, pos);
                appendStringInfoChar(&buf, '\n');
            }
        }
    }
 
    /* And finally the function definition ... */
    (void) SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_prosqlbody, &isnull);
    if (proc->prolang == SQLlanguageId && !isnull)
    {
        print_function_sqlbody(&buf, proctup);
    }
    else
    {
        appendStringInfoString(&buf, "AS ");
 
        tmp = SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_probin, &isnull);
        if (!isnull)
        {
            simple_quote_literal(&buf, TextDatumGetCString(tmp));
            appendStringInfoString(&buf, ", "); /* assume prosrc isn't null */
        }
 
        tmp = SysCacheGetAttrNotNull(PROCOID, proctup, Anum_pg_proc_prosrc);
        prosrc = TextDatumGetCString(tmp);
 
        /*
         * We always use dollar quoting.  Figure out a suitable delimiter.
         *
         * Since the user is likely to be editing the function body string, we
         * shouldn't use a short delimiter that he might easily create a
         * conflict with.  Hence prefer "$function$"/"$procedure$", but extend
         * if needed.
         */
        initStringInfo(&dq);
        appendStringInfoChar(&dq, '$');
        appendStringInfoString(&dq, (isfunction ? "function" : "procedure"));
        while (strstr(prosrc, dq.data) != NULL)
            appendStringInfoChar(&dq, 'x');
        appendStringInfoChar(&dq, '$');
 
        appendBinaryStringInfo(&buf, dq.data, dq.len);
        appendStringInfoString(&buf, prosrc);
        appendBinaryStringInfo(&buf, dq.data, dq.len);
    }
 
    appendStringInfoChar(&buf, '\n');
 
    ReleaseSysCache(proctup);
 
    PG_RETURN_TEXT_P(string_to_text(buf.data));
}
 
/*
 * pg_get_function_arguments
 *      Get a nicely-formatted list of arguments for a function.
 *      This is everything that would go between the parentheses in
 *      CREATE FUNCTION.
 */
Datum
pg_get_function_arguments(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    StringInfoData buf;
    HeapTuple   proctup;
 
    proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(proctup))
        PG_RETURN_NULL();
 
    initStringInfo(&buf);
 
    (void) print_function_arguments(&buf, proctup, false, true);
 
    ReleaseSysCache(proctup);
 
    PG_RETURN_TEXT_P(string_to_text(buf.data));
}
 
/*
 * pg_get_function_identity_arguments
 *      Get a formatted list of arguments for a function.
 *      This is everything that would go between the parentheses in
 *      ALTER FUNCTION, etc.  In particular, don't print defaults.
 */
Datum
pg_get_function_identity_arguments(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    StringInfoData buf;
    HeapTuple   proctup;
 
    proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(proctup))
        PG_RETURN_NULL();
 
    initStringInfo(&buf);
 
    (void) print_function_arguments(&buf, proctup, false, false);
 
    ReleaseSysCache(proctup);
 
    PG_RETURN_TEXT_P(string_to_text(buf.data));
}
 
/*
 * pg_get_function_result
 *      Get a nicely-formatted version of the result type of a function.
 *      This is what would appear after RETURNS in CREATE FUNCTION.
 */
Datum
pg_get_function_result(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    StringInfoData buf;
    HeapTuple   proctup;
 
    proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(proctup))
        PG_RETURN_NULL();
 
    if (((Form_pg_proc) GETSTRUCT(proctup))->prokind == PROKIND_PROCEDURE)
    {
        ReleaseSysCache(proctup);
        PG_RETURN_NULL();
    }
 
    initStringInfo(&buf);
 
    print_function_rettype(&buf, proctup);
 
    ReleaseSysCache(proctup);
 
    PG_RETURN_TEXT_P(string_to_text(buf.data));
}
 
/*
 * Guts of pg_get_function_result: append the function's return type
 * to the specified buffer.
 */
static void
print_function_rettype(StringInfo buf, HeapTuple proctup)
{
    Form_pg_proc proc = (Form_pg_proc) GETSTRUCT(proctup);
    int         ntabargs = 0;
    StringInfoData rbuf;
 
    initStringInfo(&rbuf);
 
    if (proc->proretset)
    {
        /* It might be a table function; try to print the arguments */
        appendStringInfoString(&rbuf, "TABLE(");
        ntabargs = print_function_arguments(&rbuf, proctup, true, false);
        if (ntabargs > 0)
            appendStringInfoChar(&rbuf, ')');
        else
            resetStringInfo(&rbuf);
    }
 
    if (ntabargs == 0)
    {
        /* Not a table function, so do the normal thing */
        if (proc->proretset)
            appendStringInfoString(&rbuf, "SETOF ");
        appendStringInfoString(&rbuf, format_type_be(proc->prorettype));
    }
 
    appendBinaryStringInfo(buf, rbuf.data, rbuf.len);
}
 
/*
 * Common code for pg_get_function_arguments and pg_get_function_result:
 * append the desired subset of arguments to buf.  We print only TABLE
 * arguments when print_table_args is true, and all the others when it's false.
 * We print argument defaults only if print_defaults is true.
 * Function return value is the number of arguments printed.
 */
static int
print_function_arguments(StringInfo buf, HeapTuple proctup,
                         bool print_table_args, bool print_defaults)
{
    Form_pg_proc proc = (Form_pg_proc) GETSTRUCT(proctup);
    int         numargs;
    Oid        *argtypes;
    char      **argnames;
    char       *argmodes;
    int         insertorderbyat = -1;
    int         argsprinted;
    int         inputargno;
    int         nlackdefaults;
    List       *argdefaults = NIL;
    ListCell   *nextargdefault = NULL;
    int         i;
 
    numargs = get_func_arg_info(proctup,
                                &argtypes, &argnames, &argmodes);
 
    nlackdefaults = numargs;
    if (print_defaults && proc->pronargdefaults > 0)
    {
        Datum       proargdefaults;
        bool        isnull;
 
        proargdefaults = SysCacheGetAttr(PROCOID, proctup,
                                         Anum_pg_proc_proargdefaults,
                                         &isnull);
        if (!isnull)
        {
            char       *str;
 
            str = TextDatumGetCString(proargdefaults);
            argdefaults = castNode(List, stringToNode(str));
            pfree(str);
            nextargdefault = list_head(argdefaults);
            /* nlackdefaults counts only *input* arguments lacking defaults */
            nlackdefaults = proc->pronargs - list_length(argdefaults);
        }
    }
 
    /* Check for special treatment of ordered-set aggregates */
    if (proc->prokind == PROKIND_AGGREGATE)
    {
        HeapTuple   aggtup;
        Form_pg_aggregate agg;
 
        aggtup = SearchSysCache1(AGGFNOID, ObjectIdGetDatum(proc->oid));
        if (!HeapTupleIsValid(aggtup))
            elog(ERROR, "cache lookup failed for aggregate %u",
                 proc->oid);
        agg = (Form_pg_aggregate) GETSTRUCT(aggtup);
        if (AGGKIND_IS_ORDERED_SET(agg->aggkind))
            insertorderbyat = agg->aggnumdirectargs;
        ReleaseSysCache(aggtup);
    }
 
    argsprinted = 0;
    inputargno = 0;
    for (i = 0; i < numargs; i++)
    {
        Oid         argtype = argtypes[i];
        char       *argname = argnames ? argnames[i] : NULL;
        char        argmode = argmodes ? argmodes[i] : PROARGMODE_IN;
        const char *modename;
        bool        isinput;
 
        switch (argmode)
        {
            case PROARGMODE_IN:
 
                /*
                 * For procedures, explicitly mark all argument modes, so as
                 * to avoid ambiguity with the SQL syntax for DROP PROCEDURE.
                 */
                if (proc->prokind == PROKIND_PROCEDURE)
                    modename = "IN ";
                else
                    modename = "";
                isinput = true;
                break;
            case PROARGMODE_INOUT:
                modename = "INOUT ";
                isinput = true;
                break;
            case PROARGMODE_OUT:
                modename = "OUT ";
                isinput = false;
                break;
            case PROARGMODE_VARIADIC:
                modename = "VARIADIC ";
                isinput = true;
                break;
            case PROARGMODE_TABLE:
                modename = "";
                isinput = false;
                break;
            default:
                elog(ERROR, "invalid parameter mode '%c'", argmode);
                modename = NULL;    /* keep compiler quiet */
                isinput = false;
                break;
        }
        if (isinput)
            inputargno++;       /* this is a 1-based counter */
 
        if (print_table_args != (argmode == PROARGMODE_TABLE))
            continue;
 
        if (argsprinted == insertorderbyat)
        {
            if (argsprinted)
                appendStringInfoChar(buf, ' ');
            appendStringInfoString(buf, "ORDER BY ");
        }
        else if (argsprinted)
            appendStringInfoString(buf, ", ");
 
        appendStringInfoString(buf, modename);
        if (argname && argname[0])
            appendStringInfo(buf, "%s ", quote_identifier(argname));
        appendStringInfoString(buf, format_type_be(argtype));
        if (print_defaults && isinput && inputargno > nlackdefaults)
        {
            Node       *expr;
 
            Assert(nextargdefault != NULL);
            expr = (Node *) lfirst(nextargdefault);
            nextargdefault = lnext(argdefaults, nextargdefault);
 
            appendStringInfo(buf, " DEFAULT %s",
                             deparse_expression(expr, NIL, false, false));
        }
        argsprinted++;
 
        /* nasty hack: print the last arg twice for variadic ordered-set agg */
        if (argsprinted == insertorderbyat && i == numargs - 1)
        {
            i--;
            /* aggs shouldn't have defaults anyway, but just to be sure ... */
            print_defaults = false;
        }
    }
 
    return argsprinted;
}
 
static bool
is_input_argument(int nth, const char *argmodes)
{
    return (!argmodes
            || argmodes[nth] == PROARGMODE_IN
            || argmodes[nth] == PROARGMODE_INOUT
            || argmodes[nth] == PROARGMODE_VARIADIC);
}
 
/*
 * Append used transformed types to specified buffer
 */
static void
print_function_trftypes(StringInfo buf, HeapTuple proctup)
{
    Oid        *trftypes;
    int         ntypes;
 
    ntypes = get_func_trftypes(proctup, &trftypes);
    if (ntypes > 0)
    {
        int         i;
 
        appendStringInfoString(buf, " TRANSFORM ");
        for (i = 0; i < ntypes; i++)
        {
            if (i != 0)
                appendStringInfoString(buf, ", ");
            appendStringInfo(buf, "FOR TYPE %s", format_type_be(trftypes[i]));
        }
        appendStringInfoChar(buf, '\n');
    }
}
 
/*
 * Get textual representation of a function argument's default value.  The
 * second argument of this function is the argument number among all arguments
 * (i.e. proallargtypes, *not* proargtypes), starting with 1, because that's
 * how information_schema.sql uses it.
 */
Datum
pg_get_function_arg_default(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    int32       nth_arg = PG_GETARG_INT32(1);
    HeapTuple   proctup;
    Form_pg_proc proc;
    int         numargs;
    Oid        *argtypes;
    char      **argnames;
    char       *argmodes;
    int         i;
    List       *argdefaults;
    Node       *node;
    char       *str;
    int         nth_inputarg;
    Datum       proargdefaults;
    bool        isnull;
    int         nth_default;
 
    proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(proctup))
        PG_RETURN_NULL();
 
    numargs = get_func_arg_info(proctup, &argtypes, &argnames, &argmodes);
    if (nth_arg < 1 || nth_arg > numargs || !is_input_argument(nth_arg - 1, argmodes))
    {
        ReleaseSysCache(proctup);
        PG_RETURN_NULL();
    }
 
    nth_inputarg = 0;
    for (i = 0; i < nth_arg; i++)
        if (is_input_argument(i, argmodes))
            nth_inputarg++;
 
    proargdefaults = SysCacheGetAttr(PROCOID, proctup,
                                     Anum_pg_proc_proargdefaults,
                                     &isnull);
    if (isnull)
    {
        ReleaseSysCache(proctup);
        PG_RETURN_NULL();
    }
 
    str = TextDatumGetCString(proargdefaults);
    argdefaults = castNode(List, stringToNode(str));
    pfree(str);
 
    proc = (Form_pg_proc) GETSTRUCT(proctup);
 
    /*
     * Calculate index into proargdefaults: proargdefaults corresponds to the
     * last N input arguments, where N = pronargdefaults.
     */
    nth_default = nth_inputarg - 1 - (proc->pronargs - proc->pronargdefaults);
 
    if (nth_default < 0 || nth_default >= list_length(argdefaults))
    {
        ReleaseSysCache(proctup);
        PG_RETURN_NULL();
    }
    node = list_nth(argdefaults, nth_default);
    str = deparse_expression(node, NIL, false, false);
 
    ReleaseSysCache(proctup);
 
    PG_RETURN_TEXT_P(string_to_text(str));
}
 
static void
print_function_sqlbody(StringInfo buf, HeapTuple proctup)
{
    int         numargs;
    Oid        *argtypes;
    char      **argnames;
    char       *argmodes;
    deparse_namespace dpns = {0};
    Datum       tmp;
    Node       *n;
 
    dpns.funcname = pstrdup(NameStr(((Form_pg_proc) GETSTRUCT(proctup))->proname));
    numargs = get_func_arg_info(proctup,
                                &argtypes, &argnames, &argmodes);
    dpns.numargs = numargs;
    dpns.argnames = argnames;
 
    tmp = SysCacheGetAttrNotNull(PROCOID, proctup, Anum_pg_proc_prosqlbody);
    n = stringToNode(TextDatumGetCString(tmp));
 
    if (IsA(n, List))
    {
        List       *stmts;
        ListCell   *lc;
 
        stmts = linitial(castNode(List, n));
 
        appendStringInfoString(buf, "BEGIN ATOMIC\n");
 
        foreach(lc, stmts)
        {
            Query      *query = lfirst_node(Query, lc);
 
            /* It seems advisable to get at least AccessShareLock on rels */
            AcquireRewriteLocks(query, false, false);
            get_query_def(query, buf, list_make1(&dpns), NULL, false,
                          PRETTYFLAG_INDENT, WRAP_COLUMN_DEFAULT, 1);
            appendStringInfoChar(buf, ';');
            appendStringInfoChar(buf, '\n');
        }
 
        appendStringInfoString(buf, "END");
    }
    else
    {
        Query      *query = castNode(Query, n);
 
        /* It seems advisable to get at least AccessShareLock on rels */
        AcquireRewriteLocks(query, false, false);
        get_query_def(query, buf, list_make1(&dpns), NULL, false,
                      0, WRAP_COLUMN_DEFAULT, 0);
    }
}
 
Datum
pg_get_function_sqlbody(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    StringInfoData buf;
    HeapTuple   proctup;
    bool        isnull;
 
    initStringInfo(&buf);
 
    /* Look up the function */
    proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(proctup))
        PG_RETURN_NULL();
 
    (void) SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_prosqlbody, &isnull);
    if (isnull)
    {
        ReleaseSysCache(proctup);
        PG_RETURN_NULL();
    }
 
    print_function_sqlbody(&buf, proctup);
 
    ReleaseSysCache(proctup);
 
    PG_RETURN_TEXT_P(cstring_to_text_with_len(buf.data, buf.len));
}
 
 
/*
 * deparse_expression           - General utility for deparsing expressions
 *
 * calls deparse_expression_pretty with all prettyPrinting disabled
 */
char *
deparse_expression(Node *expr, List *dpcontext,
                   bool forceprefix, bool showimplicit)
{
    return deparse_expression_pretty(expr, dpcontext, forceprefix,
                                     showimplicit, 0, 0);
}
 
/* ----------
 * deparse_expression_pretty    - General utility for deparsing expressions
 *
 * expr is the node tree to be deparsed.  It must be a transformed expression
 * tree (ie, not the raw output of gram.y).
 *
 * dpcontext is a list of deparse_namespace nodes representing the context
 * for interpreting Vars in the node tree.  It can be NIL if no Vars are
 * expected.
 *
 * forceprefix is true to force all Vars to be prefixed with their table names.
 *
 * showimplicit is true to force all implicit casts to be shown explicitly.
 *
 * Tries to pretty up the output according to prettyFlags and startIndent.
 *
 * The result is a palloc'd string.
 * ----------
 */
static char *
deparse_expression_pretty(Node *expr, List *dpcontext,
                          bool forceprefix, bool showimplicit,
                          int prettyFlags, int startIndent)
{
    StringInfoData buf;
    deparse_context context;
 
    initStringInfo(&buf);
    context.buf = &buf;
    context.namespaces = dpcontext;
    context.resultDesc = NULL;
    context.targetList = NIL;
    context.windowClause = NIL;
    context.varprefix = forceprefix;
    context.prettyFlags = prettyFlags;
    context.wrapColumn = WRAP_COLUMN_DEFAULT;
    context.indentLevel = startIndent;
    context.colNamesVisible = true;
    context.inGroupBy = false;
    context.varInOrderBy = false;
    context.appendparents = NULL;
 
    get_rule_expr(expr, &context, showimplicit);
 
    return buf.data;
}
 
/* ----------
 * deparse_context_for          - Build deparse context for a single relation
 *
 * Given the reference name (alias) and OID of a relation, build deparsing
 * context for an expression referencing only that relation (as varno 1,
 * varlevelsup 0).  This is sufficient for many uses of deparse_expression.
 * ----------
 */
List *
deparse_context_for(const char *aliasname, Oid relid)
{
    deparse_namespace *dpns;
    RangeTblEntry *rte;
 
    dpns = (deparse_namespace *) palloc0(sizeof(deparse_namespace));
 
    /* Build a minimal RTE for the rel */
    rte = makeNode(RangeTblEntry);
    rte->rtekind = RTE_RELATION;
    rte->relid = relid;
    rte->relkind = RELKIND_RELATION;    /* no need for exactness here */
    rte->rellockmode = AccessShareLock;
    rte->alias = makeAlias(aliasname, NIL);
    rte->eref = rte->alias;
    rte->lateral = false;
    rte->inh = false;
    rte->inFromCl = true;
 
    /* Build one-element rtable */
    dpns->rtable = list_make1(rte);
    dpns->subplans = NIL;
    dpns->ctes = NIL;
    dpns->appendrels = NULL;
    set_rtable_names(dpns, NIL, NULL);
    set_simple_column_names(dpns);
 
    /* Return a one-deep namespace stack */
    return list_make1(dpns);
}
 
/*
 * deparse_context_for_plan_tree - Build deparse context for a Plan tree
 *
 * When deparsing an expression in a Plan tree, we use the plan's rangetable
 * to resolve names of simple Vars.  The initialization of column names for
 * this is rather expensive if the rangetable is large, and it'll be the same
 * for every expression in the Plan tree; so we do it just once and re-use
 * the result of this function for each expression.  (Note that the result
 * is not usable until set_deparse_context_plan() is applied to it.)
 *
 * In addition to the PlannedStmt, pass the per-RTE alias names
 * assigned by a previous call to select_rtable_names_for_explain.
 */
List *
deparse_context_for_plan_tree(PlannedStmt *pstmt, List *rtable_names)
{
    deparse_namespace *dpns;
 
    dpns = (deparse_namespace *) palloc0(sizeof(deparse_namespace));
 
    /* Initialize fields that stay the same across the whole plan tree */
    dpns->rtable = pstmt->rtable;
    dpns->rtable_names = rtable_names;
    dpns->subplans = pstmt->subplans;
    dpns->ctes = NIL;
    if (pstmt->appendRelations)
    {
        /* Set up the array, indexed by child relid */
        int         ntables = list_length(dpns->rtable);
        ListCell   *lc;
 
        dpns->appendrels = (AppendRelInfo **)
            palloc0((ntables + 1) * sizeof(AppendRelInfo *));
        foreach(lc, pstmt->appendRelations)
        {
            AppendRelInfo *appinfo = lfirst_node(AppendRelInfo, lc);
            Index       crelid = appinfo->child_relid;
 
            Assert(crelid > 0 && crelid <= ntables);
            Assert(dpns->appendrels[crelid] == NULL);
            dpns->appendrels[crelid] = appinfo;
        }
    }
    else
        dpns->appendrels = NULL;    /* don't need it */
 
    /*
     * Set up column name aliases, ignoring any join RTEs; they don't matter
     * because plan trees don't contain any join alias Vars.
     */
    set_simple_column_names(dpns);
 
    /* Return a one-deep namespace stack */
    return list_make1(dpns);
}
 
/*
 * set_deparse_context_plan - Specify Plan node containing expression
 *
 * When deparsing an expression in a Plan tree, we might have to resolve
 * OUTER_VAR, INNER_VAR, or INDEX_VAR references.  To do this, the caller must
 * provide the parent Plan node.  Then OUTER_VAR and INNER_VAR references
 * can be resolved by drilling down into the left and right child plans.
 * Similarly, INDEX_VAR references can be resolved by reference to the
 * indextlist given in a parent IndexOnlyScan node, or to the scan tlist in
 * ForeignScan and CustomScan nodes.  (Note that we don't currently support
 * deparsing of indexquals in regular IndexScan or BitmapIndexScan nodes;
 * for those, we can only deparse the indexqualorig fields, which won't
 * contain INDEX_VAR Vars.)
 *
 * The ancestors list is a list of the Plan's parent Plan and SubPlan nodes,
 * the most-closely-nested first.  This is needed to resolve PARAM_EXEC
 * Params.  Note we assume that all the Plan nodes share the same rtable.
 *
 * For a ModifyTable plan, we might also need to resolve references to OLD/NEW
 * variables in the RETURNING list, so we copy the alias names of the OLD and
 * NEW rows from the ModifyTable plan node.
 *
 * Once this function has been called, deparse_expression() can be called on
 * subsidiary expression(s) of the specified Plan node.  To deparse
 * expressions of a different Plan node in the same Plan tree, re-call this
 * function to identify the new parent Plan node.
 *
 * The result is the same List passed in; this is a notational convenience.
 */
List *
set_deparse_context_plan(List *dpcontext, Plan *plan, List *ancestors)
{
    deparse_namespace *dpns;
 
    /* Should always have one-entry namespace list for Plan deparsing */
    Assert(list_length(dpcontext) == 1);
    dpns = (deparse_namespace *) linitial(dpcontext);
 
    /* Set our attention on the specific plan node passed in */
    dpns->ancestors = ancestors;
    set_deparse_plan(dpns, plan);
 
    /* For ModifyTable, set aliases for OLD and NEW in RETURNING */
    if (IsA(plan, ModifyTable))
    {
        dpns->ret_old_alias = ((ModifyTable *) plan)->returningOldAlias;
        dpns->ret_new_alias = ((ModifyTable *) plan)->returningNewAlias;
    }
 
    return dpcontext;
}
 
/*
 * select_rtable_names_for_explain  - Select RTE aliases for EXPLAIN
 *
 * Determine the relation aliases we'll use during an EXPLAIN operation.
 * This is just a frontend to set_rtable_names.  We have to expose the aliases
 * to EXPLAIN because EXPLAIN needs to know the right alias names to print.
 */
List *
select_rtable_names_for_explain(List *rtable, Bitmapset *rels_used)
{
    deparse_namespace dpns;
 
    memset(&dpns, 0, sizeof(dpns));
    dpns.rtable = rtable;
    dpns.subplans = NIL;
    dpns.ctes = NIL;
    dpns.appendrels = NULL;
    set_rtable_names(&dpns, NIL, rels_used);
    /* We needn't bother computing column aliases yet */
 
    return dpns.rtable_names;
}
 
/*
 * set_rtable_names: select RTE aliases to be used in printing a query
 *
 * We fill in dpns->rtable_names with a list of names that is one-for-one with
 * the already-filled dpns->rtable list.  Each RTE name is unique among those
 * in the new namespace plus any ancestor namespaces listed in
 * parent_namespaces.
 *
 * If rels_used isn't NULL, only RTE indexes listed in it are given aliases.
 *
 * Note that this function is only concerned with relation names, not column
 * names.
 */
static void
set_rtable_names(deparse_namespace *dpns, List *parent_namespaces,
                 Bitmapset *rels_used)
{
    HASHCTL     hash_ctl;
    HTAB       *names_hash;
    NameHashEntry *hentry;
    bool        found;
    int         rtindex;
    ListCell   *lc;
 
    dpns->rtable_names = NIL;
    /* nothing more to do if empty rtable */
    if (dpns->rtable == NIL)
        return;
 
    /*
     * We use a hash table to hold known names, so that this process is O(N)
     * not O(N^2) for N names.
     */
    hash_ctl.keysize = NAMEDATALEN;
    hash_ctl.entrysize = sizeof(NameHashEntry);
    hash_ctl.hcxt = CurrentMemoryContext;
    names_hash = hash_create("set_rtable_names names",
                             list_length(dpns->rtable),
                             &hash_ctl,
                             HASH_ELEM | HASH_STRINGS | HASH_CONTEXT);
 
    /* Preload the hash table with names appearing in parent_namespaces */
    foreach(lc, parent_namespaces)
    {
        deparse_namespace *olddpns = (deparse_namespace *) lfirst(lc);
        ListCell   *lc2;
 
        foreach(lc2, olddpns->rtable_names)
        {
            char       *oldname = (char *) lfirst(lc2);
 
            if (oldname == NULL)
                continue;
            hentry = (NameHashEntry *) hash_search(names_hash,
                                                   oldname,
                                                   HASH_ENTER,
                                                   &found);
            /* we do not complain about duplicate names in parent namespaces */
            hentry->counter = 0;
        }
    }
 
    /* Now we can scan the rtable */
    rtindex = 1;
    foreach(lc, dpns->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
        char       *refname;
 
        /* Just in case this takes an unreasonable amount of time ... */
        CHECK_FOR_INTERRUPTS();
 
        if (rels_used && !bms_is_member(rtindex, rels_used))
        {
            /* Ignore unreferenced RTE */
            refname = NULL;
        }
        else if (rte->alias)
        {
            /* If RTE has a user-defined alias, prefer that */
            refname = rte->alias->aliasname;
        }
        else if (rte->rtekind == RTE_RELATION)
        {
            /* Use the current actual name of the relation */
            refname = get_rel_name(rte->relid);
        }
        else if (rte->rtekind == RTE_JOIN)
        {
            /* Unnamed join has no refname */
            refname = NULL;
        }
        else
        {
            /* Otherwise use whatever the parser assigned */
            refname = rte->eref->aliasname;
        }
 
        /*
         * If the selected name isn't unique, append digits to make it so, and
         * make a new hash entry for it once we've got a unique name.  For a
         * very long input name, we might have to truncate to stay within
         * NAMEDATALEN.
         */
        if (refname)
        {
            hentry = (NameHashEntry *) hash_search(names_hash,
                                                   refname,
                                                   HASH_ENTER,
                                                   &found);
            if (found)
            {
                /* Name already in use, must choose a new one */
                int         refnamelen = strlen(refname);
                char       *modname = (char *) palloc(refnamelen + 16);
                NameHashEntry *hentry2;
 
                do
                {
                    hentry->counter++;
                    for (;;)
                    {
                        memcpy(modname, refname, refnamelen);
                        sprintf(modname + refnamelen, "_%d", hentry->counter);
                        if (strlen(modname) < NAMEDATALEN)
                            break;
                        /* drop chars from refname to keep all the digits */
                        refnamelen = pg_mbcliplen(refname, refnamelen,
                                                  refnamelen - 1);
                    }
                    hentry2 = (NameHashEntry *) hash_search(names_hash,
                                                            modname,
                                                            HASH_ENTER,
                                                            &found);
                } while (found);
                hentry2->counter = 0;   /* init new hash entry */
                refname = modname;
            }
            else
            {
                /* Name not previously used, need only initialize hentry */
                hentry->counter = 0;
            }
        }
 
        dpns->rtable_names = lappend(dpns->rtable_names, refname);
        rtindex++;
    }
 
    hash_destroy(names_hash);
}
 
/*
 * set_deparse_for_query: set up deparse_namespace for deparsing a Query tree
 *
 * For convenience, this is defined to initialize the deparse_namespace struct
 * from scratch.
 */
static void
set_deparse_for_query(deparse_namespace *dpns, Query *query,
                      List *parent_namespaces)
{
    ListCell   *lc;
    ListCell   *lc2;
 
    /* Initialize *dpns and fill rtable/ctes links */
    memset(dpns, 0, sizeof(deparse_namespace));
    dpns->rtable = query->rtable;
    dpns->subplans = NIL;
    dpns->ctes = query->cteList;
    dpns->appendrels = NULL;
    dpns->ret_old_alias = query->returningOldAlias;
    dpns->ret_new_alias = query->returningNewAlias;
 
    /* Assign a unique relation alias to each RTE */
    set_rtable_names(dpns, parent_namespaces, NULL);
 
    /* Initialize dpns->rtable_columns to contain zeroed structs */
    dpns->rtable_columns = NIL;
    while (list_length(dpns->rtable_columns) < list_length(dpns->rtable))
        dpns->rtable_columns = lappend(dpns->rtable_columns,
                                       palloc0(sizeof(deparse_columns)));
 
    /* If it's a utility query, it won't have a jointree */
    if (query->jointree)
    {
        /* Detect whether global uniqueness of USING names is needed */
        dpns->unique_using =
            has_dangerous_join_using(dpns, (Node *) query->jointree);
 
        /*
         * Select names for columns merged by USING, via a recursive pass over
         * the query jointree.
         */
        set_using_names(dpns, (Node *) query->jointree, NIL);
    }
 
    /*
     * Now assign remaining column aliases for each RTE.  We do this in a
     * linear scan of the rtable, so as to process RTEs whether or not they
     * are in the jointree (we mustn't miss NEW.*, INSERT target relations,
     * etc).  JOIN RTEs must be processed after their children, but this is
     * okay because they appear later in the rtable list than their children
     * (cf Asserts in identify_join_columns()).
     */
    forboth(lc, dpns->rtable, lc2, dpns->rtable_columns)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
        deparse_columns *colinfo = (deparse_columns *) lfirst(lc2);
 
        if (rte->rtekind == RTE_JOIN)
            set_join_column_names(dpns, rte, colinfo);
        else
            set_relation_column_names(dpns, rte, colinfo);
    }
}
 
/*
 * set_simple_column_names: fill in column aliases for non-query situations
 *
 * This handles EXPLAIN and cases where we only have relation RTEs.  Without
 * a join tree, we can't do anything smart about join RTEs, but we don't
 * need to, because EXPLAIN should never see join alias Vars anyway.
 * If we find a join RTE we'll just skip it, leaving its deparse_columns
 * struct all-zero.  If somehow we try to deparse a join alias Var, we'll
 * error out cleanly because the struct's num_cols will be zero.
 */
static void
set_simple_column_names(deparse_namespace *dpns)
{
    ListCell   *lc;
    ListCell   *lc2;
 
    /* Initialize dpns->rtable_columns to contain zeroed structs */
    dpns->rtable_columns = NIL;
    while (list_length(dpns->rtable_columns) < list_length(dpns->rtable))
        dpns->rtable_columns = lappend(dpns->rtable_columns,
                                       palloc0(sizeof(deparse_columns)));
 
    /* Assign unique column aliases within each non-join RTE */
    forboth(lc, dpns->rtable, lc2, dpns->rtable_columns)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
        deparse_columns *colinfo = (deparse_columns *) lfirst(lc2);
 
        if (rte->rtekind != RTE_JOIN)
            set_relation_column_names(dpns, rte, colinfo);
    }
}
 
/*
 * has_dangerous_join_using: search jointree for unnamed JOIN USING
 *
 * Merged columns of a JOIN USING may act differently from either of the input
 * columns, either because they are merged with COALESCE (in a FULL JOIN) or
 * because an implicit coercion of the underlying input column is required.
 * In such a case the column must be referenced as a column of the JOIN not as
 * a column of either input.  And this is problematic if the join is unnamed
 * (alias-less): we cannot qualify the column's name with an RTE name, since
 * there is none.  (Forcibly assigning an alias to the join is not a solution,
 * since that will prevent legal references to tables below the join.)
 * To ensure that every column in the query is unambiguously referenceable,
 * we must assign such merged columns names that are globally unique across
 * the whole query, aliasing other columns out of the way as necessary.
 *
 * Because the ensuing re-aliasing is fairly damaging to the readability of
 * the query, we don't do this unless we have to.  So, we must pre-scan
 * the join tree to see if we have to, before starting set_using_names().
 */
static bool
has_dangerous_join_using(deparse_namespace *dpns, Node *jtnode)
{
    if (IsA(jtnode, RangeTblRef))
    {
        /* nothing to do here */
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *lc;
 
        foreach(lc, f->fromlist)
        {
            if (has_dangerous_join_using(dpns, (Node *) lfirst(lc)))
                return true;
        }
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;
 
        /* Is it an unnamed JOIN with USING? */
        if (j->alias == NULL && j->usingClause)
        {
            /*
             * Yes, so check each join alias var to see if any of them are not
             * simple references to underlying columns.  If so, we have a
             * dangerous situation and must pick unique aliases.
             */
            RangeTblEntry *jrte = rt_fetch(j->rtindex, dpns->rtable);
 
            /* We need only examine the merged columns */
            for (int i = 0; i < jrte->joinmergedcols; i++)
            {
                Node       *aliasvar = list_nth(jrte->joinaliasvars, i);
 
                if (!IsA(aliasvar, Var))
                    return true;
            }
        }
 
        /* Nope, but inspect children */
        if (has_dangerous_join_using(dpns, j->larg))
            return true;
        if (has_dangerous_join_using(dpns, j->rarg))
            return true;
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
    return false;
}
 
/*
 * set_using_names: select column aliases to be used for merged USING columns
 *
 * We do this during a recursive descent of the query jointree.
 * dpns->unique_using must already be set to determine the global strategy.
 *
 * Column alias info is saved in the dpns->rtable_columns list, which is
 * assumed to be filled with pre-zeroed deparse_columns structs.
 *
 * parentUsing is a list of all USING aliases assigned in parent joins of
 * the current jointree node.  (The passed-in list must not be modified.)
 *
 * Note that we do not use per-deparse_columns hash tables in this function.
 * The number of names that need to be assigned should be small enough that
 * we don't need to trouble with that.
 */
static void
set_using_names(deparse_namespace *dpns, Node *jtnode, List *parentUsing)
{
    if (IsA(jtnode, RangeTblRef))
    {
        /* nothing to do now */
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *lc;
 
        foreach(lc, f->fromlist)
            set_using_names(dpns, (Node *) lfirst(lc), parentUsing);
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;
        RangeTblEntry *rte = rt_fetch(j->rtindex, dpns->rtable);
        deparse_columns *colinfo = deparse_columns_fetch(j->rtindex, dpns);
        int        *leftattnos;
        int        *rightattnos;
        deparse_columns *leftcolinfo;
        deparse_columns *rightcolinfo;
        int         i;
        ListCell   *lc;
 
        /* Get info about the shape of the join */
        identify_join_columns(j, rte, colinfo);
        leftattnos = colinfo->leftattnos;
        rightattnos = colinfo->rightattnos;
 
        /* Look up the not-yet-filled-in child deparse_columns structs */
        leftcolinfo = deparse_columns_fetch(colinfo->leftrti, dpns);
        rightcolinfo = deparse_columns_fetch(colinfo->rightrti, dpns);
 
        /*
         * If this join is unnamed, then we cannot substitute new aliases at
         * this level, so any name requirements pushed down to here must be
         * pushed down again to the children.
         */
        if (rte->alias == NULL)
        {
            for (i = 0; i < colinfo->num_cols; i++)
            {
                char       *colname = colinfo->colnames[i];
 
                if (colname == NULL)
                    continue;
 
                /* Push down to left column, unless it's a system column */
                if (leftattnos[i] > 0)
                {
                    expand_colnames_array_to(leftcolinfo, leftattnos[i]);
                    leftcolinfo->colnames[leftattnos[i] - 1] = colname;
                }
 
                /* Same on the righthand side */
                if (rightattnos[i] > 0)
                {
                    expand_colnames_array_to(rightcolinfo, rightattnos[i]);
                    rightcolinfo->colnames[rightattnos[i] - 1] = colname;
                }
            }
        }
 
        /*
         * If there's a USING clause, select the USING column names and push
         * those names down to the children.  We have two strategies:
         *
         * If dpns->unique_using is true, we force all USING names to be
         * unique across the whole query level.  In principle we'd only need
         * the names of dangerous USING columns to be globally unique, but to
         * safely assign all USING names in a single pass, we have to enforce
         * the same uniqueness rule for all of them.  However, if a USING
         * column's name has been pushed down from the parent, we should use
         * it as-is rather than making a uniqueness adjustment.  This is
         * necessary when we're at an unnamed join, and it creates no risk of
         * ambiguity.  Also, if there's a user-written output alias for a
         * merged column, we prefer to use that rather than the input name;
         * this simplifies the logic and seems likely to lead to less aliasing
         * overall.
         *
         * If dpns->unique_using is false, we only need USING names to be
         * unique within their own join RTE.  We still need to honor
         * pushed-down names, though.
         *
         * Though significantly different in results, these two strategies are
         * implemented by the same code, with only the difference of whether
         * to put assigned names into dpns->using_names.
         */
        if (j->usingClause)
        {
            /* Copy the input parentUsing list so we don't modify it */
            parentUsing = list_copy(parentUsing);
 
            /* USING names must correspond to the first join output columns */
            expand_colnames_array_to(colinfo, list_length(j->usingClause));
            i = 0;
            foreach(lc, j->usingClause)
            {
                char       *colname = strVal(lfirst(lc));
 
                /* Assert it's a merged column */
                Assert(leftattnos[i] != 0 && rightattnos[i] != 0);
 
                /* Adopt passed-down name if any, else select unique name */
                if (colinfo->colnames[i] != NULL)
                    colname = colinfo->colnames[i];
                else
                {
                    /* Prefer user-written output alias if any */
                    if (rte->alias && i < list_length(rte->alias->colnames))
                        colname = strVal(list_nth(rte->alias->colnames, i));
                    /* Make it appropriately unique */
                    colname = make_colname_unique(colname, dpns, colinfo);
                    if (dpns->unique_using)
                        dpns->using_names = lappend(dpns->using_names,
                                                    colname);
                    /* Save it as output column name, too */
                    colinfo->colnames[i] = colname;
                }
 
                /* Remember selected names for use later */
                colinfo->usingNames = lappend(colinfo->usingNames, colname);
                parentUsing = lappend(parentUsing, colname);
 
                /* Push down to left column, unless it's a system column */
                if (leftattnos[i] > 0)
                {
                    expand_colnames_array_to(leftcolinfo, leftattnos[i]);
                    leftcolinfo->colnames[leftattnos[i] - 1] = colname;
                }
 
                /* Same on the righthand side */
                if (rightattnos[i] > 0)
                {
                    expand_colnames_array_to(rightcolinfo, rightattnos[i]);
                    rightcolinfo->colnames[rightattnos[i] - 1] = colname;
                }
 
                i++;
            }
        }
 
        /* Mark child deparse_columns structs with correct parentUsing info */
        leftcolinfo->parentUsing = parentUsing;
        rightcolinfo->parentUsing = parentUsing;
 
        /* Now recursively assign USING column names in children */
        set_using_names(dpns, j->larg, parentUsing);
        set_using_names(dpns, j->rarg, parentUsing);
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
}
 
/*
 * set_relation_column_names: select column aliases for a non-join RTE
 *
 * Column alias info is saved in *colinfo, which is assumed to be pre-zeroed.
 * If any colnames entries are already filled in, those override local
 * choices.
 */
static void
set_relation_column_names(deparse_namespace *dpns, RangeTblEntry *rte,
                          deparse_columns *colinfo)
{
    int         ncolumns;
    char      **real_colnames;
    bool        changed_any;
    int         noldcolumns;
    int         i;
    int         j;
 
    /*
     * Construct an array of the current "real" column names of the RTE.
     * real_colnames[] will be indexed by physical column number, with NULL
     * entries for dropped columns.
     */
    if (rte->rtekind == RTE_RELATION)
    {
        /* Relation --- look to the system catalogs for up-to-date info */
        Relation    rel;
        TupleDesc   tupdesc;
 
        rel = relation_open(rte->relid, AccessShareLock);
        tupdesc = RelationGetDescr(rel);
 
        ncolumns = tupdesc->natts;
        real_colnames = (char **) palloc(ncolumns * sizeof(char *));
 
        for (i = 0; i < ncolumns; i++)
        {
            Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
 
            if (attr->attisdropped)
                real_colnames[i] = NULL;
            else
                real_colnames[i] = pstrdup(NameStr(attr->attname));
        }
        relation_close(rel, AccessShareLock);
    }
    else
    {
        /* Otherwise get the column names from eref or expandRTE() */
        List       *colnames;
        ListCell   *lc;
 
        /*
         * Functions returning composites have the annoying property that some
         * of the composite type's columns might have been dropped since the
         * query was parsed.  If possible, use expandRTE() to handle that
         * case, since it has the tedious logic needed to find out about
         * dropped columns.  However, if we're explaining a plan, then we
         * don't have rte->functions because the planner thinks that won't be
         * needed later, and that breaks expandRTE().  So in that case we have
         * to rely on rte->eref, which may lead us to report a dropped
         * column's old name; that seems close enough for EXPLAIN's purposes.
         *
         * For non-RELATION, non-FUNCTION RTEs, we can just look at rte->eref,
         * which should be sufficiently up-to-date: no other RTE types can
         * have columns get dropped from under them after parsing.
         */
        if (rte->rtekind == RTE_FUNCTION && rte->functions != NIL)
        {
            /* Since we're not creating Vars, rtindex etc. don't matter */
            expandRTE(rte, 1, 0, VAR_RETURNING_DEFAULT, -1,
                      true /* include dropped */ , &colnames, NULL);
        }
        else
            colnames = rte->eref->colnames;
 
        ncolumns = list_length(colnames);
        real_colnames = (char **) palloc(ncolumns * sizeof(char *));
 
        i = 0;
        foreach(lc, colnames)
        {
            /*
             * If the column name we find here is an empty string, then it's a
             * dropped column, so change to NULL.
             */
            char       *cname = strVal(lfirst(lc));
 
            if (cname[0] == '\0')
                cname = NULL;
            real_colnames[i] = cname;
            i++;
        }
    }
 
    /*
     * Ensure colinfo->colnames has a slot for each column.  (It could be long
     * enough already, if we pushed down a name for the last column.)  Note:
     * it's possible that there are now more columns than there were when the
     * query was parsed, ie colnames could be longer than rte->eref->colnames.
     * We must assign unique aliases to the new columns too, else there could
     * be unresolved conflicts when the view/rule is reloaded.
     */
    expand_colnames_array_to(colinfo, ncolumns);
    Assert(colinfo->num_cols == ncolumns);
 
    /*
     * Make sufficiently large new_colnames and is_new_col arrays, too.
     *
     * Note: because we leave colinfo->num_new_cols zero until after the loop,
     * colname_is_unique will not consult that array, which is fine because it
     * would only be duplicate effort.
     */
    colinfo->new_colnames = (char **) palloc(ncolumns * sizeof(char *));
    colinfo->is_new_col = (bool *) palloc(ncolumns * sizeof(bool));
 
    /* If the RTE is wide enough, use a hash table to avoid O(N^2) costs */
    build_colinfo_names_hash(colinfo);
 
    /*
     * Scan the columns, select a unique alias for each one, and store it in
     * colinfo->colnames and colinfo->new_colnames.  The former array has NULL
     * entries for dropped columns, the latter omits them.  Also mark
     * new_colnames entries as to whether they are new since parse time; this
     * is the case for entries beyond the length of rte->eref->colnames.
     */
    noldcolumns = list_length(rte->eref->colnames);
    changed_any = false;
    j = 0;
    for (i = 0; i < ncolumns; i++)
    {
        char       *real_colname = real_colnames[i];
        char       *colname = colinfo->colnames[i];
 
        /* Skip dropped columns */
        if (real_colname == NULL)
        {
            Assert(colname == NULL);    /* colnames[i] is already NULL */
            continue;
        }
 
        /* If alias already assigned, that's what to use */
        if (colname == NULL)
        {
            /* If user wrote an alias, prefer that over real column name */
            if (rte->alias && i < list_length(rte->alias->colnames))
                colname = strVal(list_nth(rte->alias->colnames, i));
            else
                colname = real_colname;
 
            /* Unique-ify and insert into colinfo */
            colname = make_colname_unique(colname, dpns, colinfo);
 
            colinfo->colnames[i] = colname;
            add_to_names_hash(colinfo, colname);
        }
 
        /* Put names of non-dropped columns in new_colnames[] too */
        colinfo->new_colnames[j] = colname;
        /* And mark them as new or not */
        colinfo->is_new_col[j] = (i >= noldcolumns);
        j++;
 
        /* Remember if any assigned aliases differ from "real" name */
        if (!changed_any && strcmp(colname, real_colname) != 0)
            changed_any = true;
    }
 
    /* We're now done needing the colinfo's names_hash */
    destroy_colinfo_names_hash(colinfo);
 
    /*
     * Set correct length for new_colnames[] array.  (Note: if columns have
     * been added, colinfo->num_cols includes them, which is not really quite
     * right but is harmless, since any new columns must be at the end where
     * they won't affect varattnos of pre-existing columns.)
     */
    colinfo->num_new_cols = j;
 
    /*
     * For a relation RTE, we need only print the alias column names if any
     * are different from the underlying "real" names.  For a function RTE,
     * always emit a complete column alias list; this is to protect against
     * possible instability of the default column names (eg, from altering
     * parameter names).  For tablefunc RTEs, we never print aliases, because
     * the column names are part of the clause itself.  For other RTE types,
     * print if we changed anything OR if there were user-written column
     * aliases (since the latter would be part of the underlying "reality").
     */
    if (rte->rtekind == RTE_RELATION)
        colinfo->printaliases = changed_any;
    else if (rte->rtekind == RTE_FUNCTION)
        colinfo->printaliases = true;
    else if (rte->rtekind == RTE_TABLEFUNC)
        colinfo->printaliases = false;
    else if (rte->alias && rte->alias->colnames != NIL)
        colinfo->printaliases = true;
    else
        colinfo->printaliases = changed_any;
}
 
/*
 * set_join_column_names: select column aliases for a join RTE
 *
 * Column alias info is saved in *colinfo, which is assumed to be pre-zeroed.
 * If any colnames entries are already filled in, those override local
 * choices.  Also, names for USING columns were already chosen by
 * set_using_names().  We further expect that column alias selection has been
 * completed for both input RTEs.
 */
static void
set_join_column_names(deparse_namespace *dpns, RangeTblEntry *rte,
                      deparse_columns *colinfo)
{
    deparse_columns *leftcolinfo;
    deparse_columns *rightcolinfo;
    bool        changed_any;
    int         noldcolumns;
    int         nnewcolumns;
    Bitmapset  *leftmerged = NULL;
    Bitmapset  *rightmerged = NULL;
    int         i;
    int         j;
    int         ic;
    int         jc;
 
    /* Look up the previously-filled-in child deparse_columns structs */
    leftcolinfo = deparse_columns_fetch(colinfo->leftrti, dpns);
    rightcolinfo = deparse_columns_fetch(colinfo->rightrti, dpns);
 
    /*
     * Ensure colinfo->colnames has a slot for each column.  (It could be long
     * enough already, if we pushed down a name for the last column.)  Note:
     * it's possible that one or both inputs now have more columns than there
     * were when the query was parsed, but we'll deal with that below.  We
     * only need entries in colnames for pre-existing columns.
     */
    noldcolumns = list_length(rte->eref->colnames);
    expand_colnames_array_to(colinfo, noldcolumns);
    Assert(colinfo->num_cols == noldcolumns);
 
    /* If the RTE is wide enough, use a hash table to avoid O(N^2) costs */
    build_colinfo_names_hash(colinfo);
 
    /*
     * Scan the join output columns, select an alias for each one, and store
     * it in colinfo->colnames.  If there are USING columns, set_using_names()
     * already selected their names, so we can start the loop at the first
     * non-merged column.
     */
    changed_any = false;
    for (i = list_length(colinfo->usingNames); i < noldcolumns; i++)
    {
        char       *colname = colinfo->colnames[i];
        char       *real_colname;
 
        /* Join column must refer to at least one input column */
        Assert(colinfo->leftattnos[i] != 0 || colinfo->rightattnos[i] != 0);
 
        /* Get the child column name */
        if (colinfo->leftattnos[i] > 0)
            real_colname = leftcolinfo->colnames[colinfo->leftattnos[i] - 1];
        else if (colinfo->rightattnos[i] > 0)
            real_colname = rightcolinfo->colnames[colinfo->rightattnos[i] - 1];
        else
        {
            /* We're joining system columns --- use eref name */
            real_colname = strVal(list_nth(rte->eref->colnames, i));
        }
 
        /* If child col has been dropped, no need to assign a join colname */
        if (real_colname == NULL)
        {
            colinfo->colnames[i] = NULL;
            continue;
        }
 
        /* In an unnamed join, just report child column names as-is */
        if (rte->alias == NULL)
        {
            colinfo->colnames[i] = real_colname;
            add_to_names_hash(colinfo, real_colname);
            continue;
        }
 
        /* If alias already assigned, that's what to use */
        if (colname == NULL)
        {
            /* If user wrote an alias, prefer that over real column name */
            if (rte->alias && i < list_length(rte->alias->colnames))
                colname = strVal(list_nth(rte->alias->colnames, i));
            else
                colname = real_colname;
 
            /* Unique-ify and insert into colinfo */
            colname = make_colname_unique(colname, dpns, colinfo);
 
            colinfo->colnames[i] = colname;
            add_to_names_hash(colinfo, colname);
        }
 
        /* Remember if any assigned aliases differ from "real" name */
        if (!changed_any && strcmp(colname, real_colname) != 0)
            changed_any = true;
    }
 
    /*
     * Calculate number of columns the join would have if it were re-parsed
     * now, and create storage for the new_colnames and is_new_col arrays.
     *
     * Note: colname_is_unique will be consulting new_colnames[] during the
     * loops below, so its not-yet-filled entries must be zeroes.
     */
    nnewcolumns = leftcolinfo->num_new_cols + rightcolinfo->num_new_cols -
        list_length(colinfo->usingNames);
    colinfo->num_new_cols = nnewcolumns;
    colinfo->new_colnames = (char **) palloc0(nnewcolumns * sizeof(char *));
    colinfo->is_new_col = (bool *) palloc0(nnewcolumns * sizeof(bool));
 
    /*
     * Generating the new_colnames array is a bit tricky since any new columns
     * added since parse time must be inserted in the right places.  This code
     * must match the parser, which will order a join's columns as merged
     * columns first (in USING-clause order), then non-merged columns from the
     * left input (in attnum order), then non-merged columns from the right
     * input (ditto).  If one of the inputs is itself a join, its columns will
     * be ordered according to the same rule, which means newly-added columns
     * might not be at the end.  We can figure out what's what by consulting
     * the leftattnos and rightattnos arrays plus the input is_new_col arrays.
     *
     * In these loops, i indexes leftattnos/rightattnos (so it's join varattno
     * less one), j indexes new_colnames/is_new_col, and ic/jc have similar
     * meanings for the current child RTE.
     */
 
    /* Handle merged columns; they are first and can't be new */
    i = j = 0;
    while (i < noldcolumns &&
           colinfo->leftattnos[i] != 0 &&
           colinfo->rightattnos[i] != 0)
    {
        /* column name is already determined and known unique */
        colinfo->new_colnames[j] = colinfo->colnames[i];
        colinfo->is_new_col[j] = false;
 
        /* build bitmapsets of child attnums of merged columns */
        if (colinfo->leftattnos[i] > 0)
            leftmerged = bms_add_member(leftmerged, colinfo->leftattnos[i]);
        if (colinfo->rightattnos[i] > 0)
            rightmerged = bms_add_member(rightmerged, colinfo->rightattnos[i]);
 
        i++, j++;
    }
 
    /* Handle non-merged left-child columns */
    ic = 0;
    for (jc = 0; jc < leftcolinfo->num_new_cols; jc++)
    {
        char       *child_colname = leftcolinfo->new_colnames[jc];
 
        if (!leftcolinfo->is_new_col[jc])
        {
            /* Advance ic to next non-dropped old column of left child */
            while (ic < leftcolinfo->num_cols &&
                   leftcolinfo->colnames[ic] == NULL)
                ic++;
            Assert(ic < leftcolinfo->num_cols);
            ic++;
            /* If it is a merged column, we already processed it */
            if (bms_is_member(ic, leftmerged))
                continue;
            /* Else, advance i to the corresponding existing join column */
            while (i < colinfo->num_cols &&
                   colinfo->colnames[i] == NULL)
                i++;
            Assert(i < colinfo->num_cols);
            Assert(ic == colinfo->leftattnos[i]);
            /* Use the already-assigned name of this column */
            colinfo->new_colnames[j] = colinfo->colnames[i];
            i++;
        }
        else
        {
            /*
             * Unique-ify the new child column name and assign, unless we're
             * in an unnamed join, in which case just copy
             */
            if (rte->alias != NULL)
            {
                colinfo->new_colnames[j] =
                    make_colname_unique(child_colname, dpns, colinfo);
                if (!changed_any &&
                    strcmp(colinfo->new_colnames[j], child_colname) != 0)
                    changed_any = true;
            }
            else
                colinfo->new_colnames[j] = child_colname;
            add_to_names_hash(colinfo, colinfo->new_colnames[j]);
        }
 
        colinfo->is_new_col[j] = leftcolinfo->is_new_col[jc];
        j++;
    }
 
    /* Handle non-merged right-child columns in exactly the same way */
    ic = 0;
    for (jc = 0; jc < rightcolinfo->num_new_cols; jc++)
    {
        char       *child_colname = rightcolinfo->new_colnames[jc];
 
        if (!rightcolinfo->is_new_col[jc])
        {
            /* Advance ic to next non-dropped old column of right child */
            while (ic < rightcolinfo->num_cols &&
                   rightcolinfo->colnames[ic] == NULL)
                ic++;
            Assert(ic < rightcolinfo->num_cols);
            ic++;
            /* If it is a merged column, we already processed it */
            if (bms_is_member(ic, rightmerged))
                continue;
            /* Else, advance i to the corresponding existing join column */
            while (i < colinfo->num_cols &&
                   colinfo->colnames[i] == NULL)
                i++;
            Assert(i < colinfo->num_cols);
            Assert(ic == colinfo->rightattnos[i]);
            /* Use the already-assigned name of this column */
            colinfo->new_colnames[j] = colinfo->colnames[i];
            i++;
        }
        else
        {
            /*
             * Unique-ify the new child column name and assign, unless we're
             * in an unnamed join, in which case just copy
             */
            if (rte->alias != NULL)
            {
                colinfo->new_colnames[j] =
                    make_colname_unique(child_colname, dpns, colinfo);
                if (!changed_any &&
                    strcmp(colinfo->new_colnames[j], child_colname) != 0)
                    changed_any = true;
            }
            else
                colinfo->new_colnames[j] = child_colname;
            add_to_names_hash(colinfo, colinfo->new_colnames[j]);
        }
 
        colinfo->is_new_col[j] = rightcolinfo->is_new_col[jc];
        j++;
    }
 
    /* Assert we processed the right number of columns */
#ifdef USE_ASSERT_CHECKING
    while (i < colinfo->num_cols && colinfo->colnames[i] == NULL)
        i++;
    Assert(i == colinfo->num_cols);
    Assert(j == nnewcolumns);
#endif
 
    /* We're now done needing the colinfo's names_hash */
    destroy_colinfo_names_hash(colinfo);
 
    /*
     * For a named join, print column aliases if we changed any from the child
     * names.  Unnamed joins cannot print aliases.
     */
    if (rte->alias != NULL)
        colinfo->printaliases = changed_any;
    else
        colinfo->printaliases = false;
}
 
/*
 * colname_is_unique: is colname distinct from already-chosen column names?
 *
 * dpns is query-wide info, colinfo is for the column's RTE
 */
static bool
colname_is_unique(const char *colname, deparse_namespace *dpns,
                  deparse_columns *colinfo)
{
    int         i;
    ListCell   *lc;
 
    /*
     * If we have a hash table, consult that instead of linearly scanning the
     * colinfo's strings.
     */
    if (colinfo->names_hash)
    {
        if (hash_search(colinfo->names_hash,
                        colname,
                        HASH_FIND,
                        NULL) != NULL)
            return false;
    }
    else
    {
        /* Check against already-assigned column aliases within RTE */
        for (i = 0; i < colinfo->num_cols; i++)
        {
            char       *oldname = colinfo->colnames[i];
 
            if (oldname && strcmp(oldname, colname) == 0)
                return false;
        }
 
        /*
         * If we're building a new_colnames array, check that too (this will
         * be partially but not completely redundant with the previous checks)
         */
        for (i = 0; i < colinfo->num_new_cols; i++)
        {
            char       *oldname = colinfo->new_colnames[i];
 
            if (oldname && strcmp(oldname, colname) == 0)
                return false;
        }
 
        /*
         * Also check against names already assigned for parent-join USING
         * cols
         */
        foreach(lc, colinfo->parentUsing)
        {
            char       *oldname = (char *) lfirst(lc);
 
            if (strcmp(oldname, colname) == 0)
                return false;
        }
    }
 
    /*
     * Also check against USING-column names that must be globally unique.
     * These are not hashed, but there should be few of them.
     */
    foreach(lc, dpns->using_names)
    {
        char       *oldname = (char *) lfirst(lc);
 
        if (strcmp(oldname, colname) == 0)
            return false;
    }
 
    return true;
}
 
/*
 * make_colname_unique: modify colname if necessary to make it unique
 *
 * dpns is query-wide info, colinfo is for the column's RTE
 */
static char *
make_colname_unique(char *colname, deparse_namespace *dpns,
                    deparse_columns *colinfo)
{
    /*
     * If the selected name isn't unique, append digits to make it so.  For a
     * very long input name, we might have to truncate to stay within
     * NAMEDATALEN.
     */
    if (!colname_is_unique(colname, dpns, colinfo))
    {
        int         colnamelen = strlen(colname);
        char       *modname = (char *) palloc(colnamelen + 16);
        int         i = 0;
 
        do
        {
            i++;
            for (;;)
            {
                memcpy(modname, colname, colnamelen);
                sprintf(modname + colnamelen, "_%d", i);
                if (strlen(modname) < NAMEDATALEN)
                    break;
                /* drop chars from colname to keep all the digits */
                colnamelen = pg_mbcliplen(colname, colnamelen,
                                          colnamelen - 1);
            }
        } while (!colname_is_unique(modname, dpns, colinfo));
        colname = modname;
    }
    return colname;
}
 
/*
 * expand_colnames_array_to: make colinfo->colnames at least n items long
 *
 * Any added array entries are initialized to zero.
 */
static void
expand_colnames_array_to(deparse_columns *colinfo, int n)
{
    if (n > colinfo->num_cols)
    {
        if (colinfo->colnames == NULL)
            colinfo->colnames = palloc0_array(char *, n);
        else
            colinfo->colnames = repalloc0_array(colinfo->colnames, char *, colinfo->num_cols, n);
        colinfo->num_cols = n;
    }
}
 
/*
 * build_colinfo_names_hash: optionally construct a hash table for colinfo
 */
static void
build_colinfo_names_hash(deparse_columns *colinfo)
{
    HASHCTL     hash_ctl;
    int         i;
    ListCell   *lc;
 
    /*
     * Use a hash table only for RTEs with at least 32 columns.  (The cutoff
     * is somewhat arbitrary, but let's choose it so that this code does get
     * exercised in the regression tests.)
     */
    if (colinfo->num_cols < 32)
        return;
 
    /*
     * Set up the hash table.  The entries are just strings with no other
     * payload.
     */
    hash_ctl.keysize = NAMEDATALEN;
    hash_ctl.entrysize = NAMEDATALEN;
    hash_ctl.hcxt = CurrentMemoryContext;
    colinfo->names_hash = hash_create("deparse_columns names",
                                      colinfo->num_cols + colinfo->num_new_cols,
                                      &hash_ctl,
                                      HASH_ELEM | HASH_STRINGS | HASH_CONTEXT);
 
    /*
     * Preload the hash table with any names already present (these would have
     * come from set_using_names).
     */
    for (i = 0; i < colinfo->num_cols; i++)
    {
        char       *oldname = colinfo->colnames[i];
 
        if (oldname)
            add_to_names_hash(colinfo, oldname);
    }
 
    for (i = 0; i < colinfo->num_new_cols; i++)
    {
        char       *oldname = colinfo->new_colnames[i];
 
        if (oldname)
            add_to_names_hash(colinfo, oldname);
    }
 
    foreach(lc, colinfo->parentUsing)
    {
        char       *oldname = (char *) lfirst(lc);
 
        add_to_names_hash(colinfo, oldname);
    }
}
 
/*
 * add_to_names_hash: add a string to the names_hash, if we're using one
 */
static void
add_to_names_hash(deparse_columns *colinfo, const char *name)
{
    if (colinfo->names_hash)
        (void) hash_search(colinfo->names_hash,
                           name,
                           HASH_ENTER,
                           NULL);
}
 
/*
 * destroy_colinfo_names_hash: destroy hash table when done with it
 */
static void
destroy_colinfo_names_hash(deparse_columns *colinfo)
{
    if (colinfo->names_hash)
    {
        hash_destroy(colinfo->names_hash);
        colinfo->names_hash = NULL;
    }
}
 
/*
 * identify_join_columns: figure out where columns of a join come from
 *
 * Fills the join-specific fields of the colinfo struct, except for
 * usingNames which is filled later.
 */
static void
identify_join_columns(JoinExpr *j, RangeTblEntry *jrte,
                      deparse_columns *colinfo)
{
    int         numjoincols;
    int         jcolno;
    int         rcolno;
    ListCell   *lc;
 
    /* Extract left/right child RT indexes */
    if (IsA(j->larg, RangeTblRef))
        colinfo->leftrti = ((RangeTblRef *) j->larg)->rtindex;
    else if (IsA(j->larg, JoinExpr))
        colinfo->leftrti = ((JoinExpr *) j->larg)->rtindex;
    else
        elog(ERROR, "unrecognized node type in jointree: %d",
             (int) nodeTag(j->larg));
    if (IsA(j->rarg, RangeTblRef))
        colinfo->rightrti = ((RangeTblRef *) j->rarg)->rtindex;
    else if (IsA(j->rarg, JoinExpr))
        colinfo->rightrti = ((JoinExpr *) j->rarg)->rtindex;
    else
        elog(ERROR, "unrecognized node type in jointree: %d",
             (int) nodeTag(j->rarg));
 
    /* Assert children will be processed earlier than join in second pass */
    Assert(colinfo->leftrti < j->rtindex);
    Assert(colinfo->rightrti < j->rtindex);
 
    /* Initialize result arrays with zeroes */
    numjoincols = list_length(jrte->joinaliasvars);
    Assert(numjoincols == list_length(jrte->eref->colnames));
    colinfo->leftattnos = (int *) palloc0(numjoincols * sizeof(int));
    colinfo->rightattnos = (int *) palloc0(numjoincols * sizeof(int));
 
    /*
     * Deconstruct RTE's joinleftcols/joinrightcols into desired format.
     * Recall that the column(s) merged due to USING are the first column(s)
     * of the join output.  We need not do anything special while scanning
     * joinleftcols, but while scanning joinrightcols we must distinguish
     * merged from unmerged columns.
     */
    jcolno = 0;
    foreach(lc, jrte->joinleftcols)
    {
        int         leftattno = lfirst_int(lc);
 
        colinfo->leftattnos[jcolno++] = leftattno;
    }
    rcolno = 0;
    foreach(lc, jrte->joinrightcols)
    {
        int         rightattno = lfirst_int(lc);
 
        if (rcolno < jrte->joinmergedcols)  /* merged column? */
            colinfo->rightattnos[rcolno] = rightattno;
        else
            colinfo->rightattnos[jcolno++] = rightattno;
        rcolno++;
    }
    Assert(jcolno == numjoincols);
}
 
/*
 * get_rtable_name: convenience function to get a previously assigned RTE alias
 *
 * The RTE must belong to the topmost namespace level in "context".
 */
static char *
get_rtable_name(int rtindex, deparse_context *context)
{
    deparse_namespace *dpns = (deparse_namespace *) linitial(context->namespaces);
 
    Assert(rtindex > 0 && rtindex <= list_length(dpns->rtable_names));
    return (char *) list_nth(dpns->rtable_names, rtindex - 1);
}
 
/*
 * set_deparse_plan: set up deparse_namespace to parse subexpressions
 * of a given Plan node
 *
 * This sets the plan, outer_plan, inner_plan, outer_tlist, inner_tlist,
 * and index_tlist fields.  Caller must already have adjusted the ancestors
 * list if necessary.  Note that the rtable, subplans, and ctes fields do
 * not need to change when shifting attention to different plan nodes in a
 * single plan tree.
 */
static void
set_deparse_plan(deparse_namespace *dpns, Plan *plan)
{
    dpns->plan = plan;
 
    /*
     * We special-case Append and MergeAppend to pretend that the first child
     * plan is the OUTER referent; we have to interpret OUTER Vars in their
     * tlists according to one of the children, and the first one is the most
     * natural choice.
     */
    if (IsA(plan, Append))
        dpns->outer_plan = linitial(((Append *) plan)->appendplans);
    else if (IsA(plan, MergeAppend))
        dpns->outer_plan = linitial(((MergeAppend *) plan)->mergeplans);
    else
        dpns->outer_plan = outerPlan(plan);
 
    if (dpns->outer_plan)
        dpns->outer_tlist = dpns->outer_plan->targetlist;
    else
        dpns->outer_tlist = NIL;
 
    /*
     * For a SubqueryScan, pretend the subplan is INNER referent.  (We don't
     * use OUTER because that could someday conflict with the normal meaning.)
     * Likewise, for a CteScan, pretend the subquery's plan is INNER referent.
     * For a WorkTableScan, locate the parent RecursiveUnion plan node and use
     * that as INNER referent.
     *
     * For MERGE, pretend the ModifyTable's source plan (its outer plan) is
     * INNER referent.  This is the join from the target relation to the data
     * source, and all INNER_VAR Vars in other parts of the query refer to its
     * targetlist.
     *
     * For ON CONFLICT .. UPDATE we just need the inner tlist to point to the
     * excluded expression's tlist. (Similar to the SubqueryScan we don't want
     * to reuse OUTER, it's used for RETURNING in some modify table cases,
     * although not INSERT .. CONFLICT).
     */
    if (IsA(plan, SubqueryScan))
        dpns->inner_plan = ((SubqueryScan *) plan)->subplan;
    else if (IsA(plan, CteScan))
        dpns->inner_plan = list_nth(dpns->subplans,
                                    ((CteScan *) plan)->ctePlanId - 1);
    else if (IsA(plan, WorkTableScan))
        dpns->inner_plan = find_recursive_union(dpns,
                                                (WorkTableScan *) plan);
    else if (IsA(plan, ModifyTable))
    {
        if (((ModifyTable *) plan)->operation == CMD_MERGE)
            dpns->inner_plan = outerPlan(plan);
        else
            dpns->inner_plan = plan;
    }
    else
        dpns->inner_plan = innerPlan(plan);
 
    if (IsA(plan, ModifyTable) && ((ModifyTable *) plan)->operation == CMD_INSERT)
        dpns->inner_tlist = ((ModifyTable *) plan)->exclRelTlist;
    else if (dpns->inner_plan)
        dpns->inner_tlist = dpns->inner_plan->targetlist;
    else
        dpns->inner_tlist = NIL;
 
    /* Set up referent for INDEX_VAR Vars, if needed */
    if (IsA(plan, IndexOnlyScan))
        dpns->index_tlist = ((IndexOnlyScan *) plan)->indextlist;
    else if (IsA(plan, ForeignScan))
        dpns->index_tlist = ((ForeignScan *) plan)->fdw_scan_tlist;
    else if (IsA(plan, CustomScan))
        dpns->index_tlist = ((CustomScan *) plan)->custom_scan_tlist;
    else
        dpns->index_tlist = NIL;
}
 
/*
 * Locate the ancestor plan node that is the RecursiveUnion generating
 * the WorkTableScan's work table.  We can match on wtParam, since that
 * should be unique within the plan tree.
 */
static Plan *
find_recursive_union(deparse_namespace *dpns, WorkTableScan *wtscan)
{
    ListCell   *lc;
 
    foreach(lc, dpns->ancestors)
    {
        Plan       *ancestor = (Plan *) lfirst(lc);
 
        if (IsA(ancestor, RecursiveUnion) &&
            ((RecursiveUnion *) ancestor)->wtParam == wtscan->wtParam)
            return ancestor;
    }
    elog(ERROR, "could not find RecursiveUnion for WorkTableScan with wtParam %d",
         wtscan->wtParam);
    return NULL;
}
 
/*
 * push_child_plan: temporarily transfer deparsing attention to a child plan
 *
 * When expanding an OUTER_VAR or INNER_VAR reference, we must adjust the
 * deparse context in case the referenced expression itself uses
 * OUTER_VAR/INNER_VAR.  We modify the top stack entry in-place to avoid
 * affecting levelsup issues (although in a Plan tree there really shouldn't
 * be any).
 *
 * Caller must provide a local deparse_namespace variable to save the
 * previous state for pop_child_plan.
 */
static void
push_child_plan(deparse_namespace *dpns, Plan *plan,
                deparse_namespace *save_dpns)
{
    /* Save state for restoration later */
    *save_dpns = *dpns;
 
    /* Link current plan node into ancestors list */
    dpns->ancestors = lcons(dpns->plan, dpns->ancestors);
 
    /* Set attention on selected child */
    set_deparse_plan(dpns, plan);
}
 
/*
 * pop_child_plan: undo the effects of push_child_plan
 */
static void
pop_child_plan(deparse_namespace *dpns, deparse_namespace *save_dpns)
{
    List       *ancestors;
 
    /* Get rid of ancestors list cell added by push_child_plan */
    ancestors = list_delete_first(dpns->ancestors);
 
    /* Restore fields changed by push_child_plan */
    *dpns = *save_dpns;
 
    /* Make sure dpns->ancestors is right (may be unnecessary) */
    dpns->ancestors = ancestors;
}
 
/*
 * push_ancestor_plan: temporarily transfer deparsing attention to an
 * ancestor plan
 *
 * When expanding a Param reference, we must adjust the deparse context
 * to match the plan node that contains the expression being printed;
 * otherwise we'd fail if that expression itself contains a Param or
 * OUTER_VAR/INNER_VAR/INDEX_VAR variable.
 *
 * The target ancestor is conveniently identified by the ListCell holding it
 * in dpns->ancestors.
 *
 * Caller must provide a local deparse_namespace variable to save the
 * previous state for pop_ancestor_plan.
 */
static void
push_ancestor_plan(deparse_namespace *dpns, ListCell *ancestor_cell,
                   deparse_namespace *save_dpns)
{
    Plan       *plan = (Plan *) lfirst(ancestor_cell);
 
    /* Save state for restoration later */
    *save_dpns = *dpns;
 
    /* Build a new ancestor list with just this node's ancestors */
    dpns->ancestors =
        list_copy_tail(dpns->ancestors,
                       list_cell_number(dpns->ancestors, ancestor_cell) + 1);
 
    /* Set attention on selected ancestor */
    set_deparse_plan(dpns, plan);
}
 
/*
 * pop_ancestor_plan: undo the effects of push_ancestor_plan
 */
static void
pop_ancestor_plan(deparse_namespace *dpns, deparse_namespace *save_dpns)
{
    /* Free the ancestor list made in push_ancestor_plan */
    list_free(dpns->ancestors);
 
    /* Restore fields changed by push_ancestor_plan */
    *dpns = *save_dpns;
}
 
 
/* ----------
 * make_ruledef         - reconstruct the CREATE RULE command
 *                for a given pg_rewrite tuple
 * ----------
 */
static void
make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
             int prettyFlags)
{
    char       *rulename;
    char        ev_type;
    Oid         ev_class;
    bool        is_instead;
    char       *ev_qual;
    char       *ev_action;
    List       *actions;
    Relation    ev_relation;
    TupleDesc   viewResultDesc = NULL;
    int         fno;
    Datum       dat;
    bool        isnull;
 
    /*
     * Get the attribute values from the rules tuple
     */
    fno = SPI_fnumber(rulettc, "rulename");
    dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
    Assert(!isnull);
    rulename = NameStr(*(DatumGetName(dat)));
 
    fno = SPI_fnumber(rulettc, "ev_type");
    dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
    Assert(!isnull);
    ev_type = DatumGetChar(dat);
 
    fno = SPI_fnumber(rulettc, "ev_class");
    dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
    Assert(!isnull);
    ev_class = DatumGetObjectId(dat);
 
    fno = SPI_fnumber(rulettc, "is_instead");
    dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
    Assert(!isnull);
    is_instead = DatumGetBool(dat);
 
    fno = SPI_fnumber(rulettc, "ev_qual");
    ev_qual = SPI_getvalue(ruletup, rulettc, fno);
    Assert(ev_qual != NULL);
 
    fno = SPI_fnumber(rulettc, "ev_action");
    ev_action = SPI_getvalue(ruletup, rulettc, fno);
    Assert(ev_action != NULL);
    actions = (List *) stringToNode(ev_action);
    if (actions == NIL)
        elog(ERROR, "invalid empty ev_action list");
 
    ev_relation = table_open(ev_class, AccessShareLock);
 
    /*
     * Build the rules definition text
     */
    appendStringInfo(buf, "CREATE RULE %s AS",
                     quote_identifier(rulename));
 
    if (prettyFlags & PRETTYFLAG_INDENT)
        appendStringInfoString(buf, "\n    ON ");
    else
        appendStringInfoString(buf, " ON ");
 
    /* The event the rule is fired for */
    switch (ev_type)
    {
        case '1':
            appendStringInfoString(buf, "SELECT");
            viewResultDesc = RelationGetDescr(ev_relation);
            break;
 
        case '2':
            appendStringInfoString(buf, "UPDATE");
            break;
 
        case '3':
            appendStringInfoString(buf, "INSERT");
            break;
 
        case '4':
            appendStringInfoString(buf, "DELETE");
            break;
 
        default:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("rule \"%s\" has unsupported event type %d",
                            rulename, ev_type)));
            break;
    }
 
    /* The relation the rule is fired on */
    appendStringInfo(buf, " TO %s",
                     (prettyFlags & PRETTYFLAG_SCHEMA) ?
                     generate_relation_name(ev_class, NIL) :
                     generate_qualified_relation_name(ev_class));
 
    /* If the rule has an event qualification, add it */
    if (strcmp(ev_qual, "<>") != 0)
    {
        Node       *qual;
        Query      *query;
        deparse_context context;
        deparse_namespace dpns;
 
        if (prettyFlags & PRETTYFLAG_INDENT)
            appendStringInfoString(buf, "\n  ");
        appendStringInfoString(buf, " WHERE ");
 
        qual = stringToNode(ev_qual);
 
        /*
         * We need to make a context for recognizing any Vars in the qual
         * (which can only be references to OLD and NEW).  Use the rtable of
         * the first query in the action list for this purpose.
         */
        query = (Query *) linitial(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.)
         */
        query = getInsertSelectQuery(query, NULL);
 
        /* Must acquire locks right away; see notes in get_query_def() */
        AcquireRewriteLocks(query, false, false);
 
        context.buf = buf;
        context.namespaces = list_make1(&dpns);
        context.resultDesc = NULL;
        context.targetList = NIL;
        context.windowClause = NIL;
        context.varprefix = (list_length(query->rtable) != 1);
        context.prettyFlags = prettyFlags;
        context.wrapColumn = WRAP_COLUMN_DEFAULT;
        context.indentLevel = PRETTYINDENT_STD;
        context.colNamesVisible = true;
        context.inGroupBy = false;
        context.varInOrderBy = false;
        context.appendparents = NULL;
 
        set_deparse_for_query(&dpns, query, NIL);
 
        get_rule_expr(qual, &context, false);
    }
 
    appendStringInfoString(buf, " DO ");
 
    /* The INSTEAD keyword (if so) */
    if (is_instead)
        appendStringInfoString(buf, "INSTEAD ");
 
    /* Finally the rules actions */
    if (list_length(actions) > 1)
    {
        ListCell   *action;
        Query      *query;
 
        appendStringInfoChar(buf, '(');
        foreach(action, actions)
        {
            query = (Query *) lfirst(action);
            get_query_def(query, buf, NIL, viewResultDesc, true,
                          prettyFlags, WRAP_COLUMN_DEFAULT, 0);
            if (prettyFlags)
                appendStringInfoString(buf, ";\n");
            else
                appendStringInfoString(buf, "; ");
        }
        appendStringInfoString(buf, ");");
    }
    else
    {
        Query      *query;
 
        query = (Query *) linitial(actions);
        get_query_def(query, buf, NIL, viewResultDesc, true,
                      prettyFlags, WRAP_COLUMN_DEFAULT, 0);
        appendStringInfoChar(buf, ';');
    }
 
    table_close(ev_relation, AccessShareLock);
}
 
 
/* ----------
 * make_viewdef         - reconstruct the SELECT part of a
 *                view rewrite rule
 * ----------
 */
static void
make_viewdef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
             int prettyFlags, int wrapColumn)
{
    Query      *query;
    char        ev_type;
    Oid         ev_class;
    bool        is_instead;
    char       *ev_qual;
    char       *ev_action;
    List       *actions;
    Relation    ev_relation;
    int         fno;
    Datum       dat;
    bool        isnull;
 
    /*
     * Get the attribute values from the rules tuple
     */
    fno = SPI_fnumber(rulettc, "ev_type");
    dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
    Assert(!isnull);
    ev_type = DatumGetChar(dat);
 
    fno = SPI_fnumber(rulettc, "ev_class");
    dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
    Assert(!isnull);
    ev_class = DatumGetObjectId(dat);
 
    fno = SPI_fnumber(rulettc, "is_instead");
    dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
    Assert(!isnull);
    is_instead = DatumGetBool(dat);
 
    fno = SPI_fnumber(rulettc, "ev_qual");
    ev_qual = SPI_getvalue(ruletup, rulettc, fno);
    Assert(ev_qual != NULL);
 
    fno = SPI_fnumber(rulettc, "ev_action");
    ev_action = SPI_getvalue(ruletup, rulettc, fno);
    Assert(ev_action != NULL);
    actions = (List *) stringToNode(ev_action);
 
    if (list_length(actions) != 1)
    {
        /* keep output buffer empty and leave */
        return;
    }
 
    query = (Query *) linitial(actions);
 
    if (ev_type != '1' || !is_instead ||
        strcmp(ev_qual, "<>") != 0 || query->commandType != CMD_SELECT)
    {
        /* keep output buffer empty and leave */
        return;
    }
 
    ev_relation = table_open(ev_class, AccessShareLock);
 
    get_query_def(query, buf, NIL, RelationGetDescr(ev_relation), true,
                  prettyFlags, wrapColumn, 0);
    appendStringInfoChar(buf, ';');
 
    table_close(ev_relation, AccessShareLock);
}
 
 
/* ----------
 * get_query_def            - Parse back one query parsetree
 *
 * query: parsetree to be displayed
 * buf: output text is appended to buf
 * parentnamespace: list (initially empty) of outer-level deparse_namespace's
 * resultDesc: if not NULL, the output tuple descriptor for the view
 *      represented by a SELECT query.  We use the column names from it
 *      to label SELECT output columns, in preference to names in the query
 * colNamesVisible: true if the surrounding context cares about the output
 *      column names at all (as, for example, an EXISTS() context does not);
 *      when false, we can suppress dummy column labels such as "?column?"
 * prettyFlags: bitmask of PRETTYFLAG_XXX options
 * wrapColumn: maximum line length, or -1 to disable wrapping
 * startIndent: initial indentation amount
 * ----------
 */
static void
get_query_def(Query *query, StringInfo buf, List *parentnamespace,
              TupleDesc resultDesc, bool colNamesVisible,
              int prettyFlags, int wrapColumn, int startIndent)
{
    deparse_context context;
    deparse_namespace dpns;
    int         rtable_size;
 
    /* Guard against excessively long or deeply-nested queries */
    CHECK_FOR_INTERRUPTS();
    check_stack_depth();
 
    rtable_size = query->hasGroupRTE ?
        list_length(query->rtable) - 1 :
        list_length(query->rtable);
 
    /*
     * Replace any Vars in the query's targetlist and havingQual that
     * reference GROUP outputs with the underlying grouping expressions.
     */
    if (query->hasGroupRTE)
    {
        query->targetList = (List *)
            flatten_group_exprs(NULL, query, (Node *) query->targetList);
        query->havingQual =
            flatten_group_exprs(NULL, query, query->havingQual);
    }
 
    /*
     * Before we begin to examine the query, acquire locks on referenced
     * relations, and fix up deleted columns in JOIN RTEs.  This ensures
     * consistent results.  Note we assume it's OK to scribble on the passed
     * querytree!
     *
     * We are only deparsing the query (we are not about to execute it), so we
     * only need AccessShareLock on the relations it mentions.
     */
    AcquireRewriteLocks(query, false, false);
 
    context.buf = buf;
    context.namespaces = lcons(&dpns, list_copy(parentnamespace));
    context.resultDesc = NULL;
    context.targetList = NIL;
    context.windowClause = NIL;
    context.varprefix = (parentnamespace != NIL ||
                         rtable_size != 1);
    context.prettyFlags = prettyFlags;
    context.wrapColumn = wrapColumn;
    context.indentLevel = startIndent;
    context.colNamesVisible = colNamesVisible;
    context.inGroupBy = false;
    context.varInOrderBy = false;
    context.appendparents = NULL;
 
    set_deparse_for_query(&dpns, query, parentnamespace);
 
    switch (query->commandType)
    {
        case CMD_SELECT:
            /* We set context.resultDesc only if it's a SELECT */
            context.resultDesc = resultDesc;
            get_select_query_def(query, &context);
            break;
 
        case CMD_UPDATE:
            get_update_query_def(query, &context);
            break;
 
        case CMD_INSERT:
            get_insert_query_def(query, &context);
            break;
 
        case CMD_DELETE:
            get_delete_query_def(query, &context);
            break;
 
        case CMD_MERGE:
            get_merge_query_def(query, &context);
            break;
 
        case CMD_NOTHING:
            appendStringInfoString(buf, "NOTHING");
            break;
 
        case CMD_UTILITY:
            get_utility_query_def(query, &context);
            break;
 
        default:
            elog(ERROR, "unrecognized query command type: %d",
                 query->commandType);
            break;
    }
}
 
/* ----------
 * get_values_def           - Parse back a VALUES list
 * ----------
 */
static void
get_values_def(List *values_lists, deparse_context *context)
{
    StringInfo  buf = context->buf;
    bool        first_list = true;
    ListCell   *vtl;
 
    appendStringInfoString(buf, "VALUES ");
 
    foreach(vtl, values_lists)
    {
        List       *sublist = (List *) lfirst(vtl);
        bool        first_col = true;
        ListCell   *lc;
 
        if (first_list)
            first_list = false;
        else
            appendStringInfoString(buf, ", ");
 
        appendStringInfoChar(buf, '(');
        foreach(lc, sublist)
        {
            Node       *col = (Node *) lfirst(lc);
 
            if (first_col)
                first_col = false;
            else
                appendStringInfoChar(buf, ',');
 
            /*
             * Print the value.  Whole-row Vars need special treatment.
             */
            get_rule_expr_toplevel(col, context, false);
        }
        appendStringInfoChar(buf, ')');
    }
}
 
/* ----------
 * get_with_clause          - Parse back a WITH clause
 * ----------
 */
static void
get_with_clause(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    const char *sep;
    ListCell   *l;
 
    if (query->cteList == NIL)
        return;
 
    if (PRETTY_INDENT(context))
    {
        context->indentLevel += PRETTYINDENT_STD;
        appendStringInfoChar(buf, ' ');
    }
 
    if (query->hasRecursive)
        sep = "WITH RECURSIVE ";
    else
        sep = "WITH ";
    foreach(l, query->cteList)
    {
        CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);
 
        appendStringInfoString(buf, sep);
        appendStringInfoString(buf, quote_identifier(cte->ctename));
        if (cte->aliascolnames)
        {
            bool        first = true;
            ListCell   *col;
 
            appendStringInfoChar(buf, '(');
            foreach(col, cte->aliascolnames)
            {
                if (first)
                    first = false;
                else
                    appendStringInfoString(buf, ", ");
                appendStringInfoString(buf,
                                       quote_identifier(strVal(lfirst(col))));
            }
            appendStringInfoChar(buf, ')');
        }
        appendStringInfoString(buf, " AS ");
        switch (cte->ctematerialized)
        {
            case CTEMaterializeDefault:
                break;
            case CTEMaterializeAlways:
                appendStringInfoString(buf, "MATERIALIZED ");
                break;
            case CTEMaterializeNever:
                appendStringInfoString(buf, "NOT MATERIALIZED ");
                break;
        }
        appendStringInfoChar(buf, '(');
        if (PRETTY_INDENT(context))
            appendContextKeyword(context, "", 0, 0, 0);
        get_query_def((Query *) cte->ctequery, buf, context->namespaces, NULL,
                      true,
                      context->prettyFlags, context->wrapColumn,
                      context->indentLevel);
        if (PRETTY_INDENT(context))
            appendContextKeyword(context, "", 0, 0, 0);
        appendStringInfoChar(buf, ')');
 
        if (cte->search_clause)
        {
            bool        first = true;
            ListCell   *lc;
 
            appendStringInfo(buf, " SEARCH %s FIRST BY ",
                             cte->search_clause->search_breadth_first ? "BREADTH" : "DEPTH");
 
            foreach(lc, cte->search_clause->search_col_list)
            {
                if (first)
                    first = false;
                else
                    appendStringInfoString(buf, ", ");
                appendStringInfoString(buf,
                                       quote_identifier(strVal(lfirst(lc))));
            }
 
            appendStringInfo(buf, " SET %s", quote_identifier(cte->search_clause->search_seq_column));
        }
 
        if (cte->cycle_clause)
        {
            bool        first = true;
            ListCell   *lc;
 
            appendStringInfoString(buf, " CYCLE ");
 
            foreach(lc, cte->cycle_clause->cycle_col_list)
            {
                if (first)
                    first = false;
                else
                    appendStringInfoString(buf, ", ");
                appendStringInfoString(buf,
                                       quote_identifier(strVal(lfirst(lc))));
            }
 
            appendStringInfo(buf, " SET %s", quote_identifier(cte->cycle_clause->cycle_mark_column));
 
            {
                Const      *cmv = castNode(Const, cte->cycle_clause->cycle_mark_value);
                Const      *cmd = castNode(Const, cte->cycle_clause->cycle_mark_default);
 
                if (!(cmv->consttype == BOOLOID && !cmv->constisnull && DatumGetBool(cmv->constvalue) == true &&
                      cmd->consttype == BOOLOID && !cmd->constisnull && DatumGetBool(cmd->constvalue) == false))
                {
                    appendStringInfoString(buf, " TO ");
                    get_rule_expr(cte->cycle_clause->cycle_mark_value, context, false);
                    appendStringInfoString(buf, " DEFAULT ");
                    get_rule_expr(cte->cycle_clause->cycle_mark_default, context, false);
                }
            }
 
            appendStringInfo(buf, " USING %s", quote_identifier(cte->cycle_clause->cycle_path_column));
        }
 
        sep = ", ";
    }
 
    if (PRETTY_INDENT(context))
    {
        context->indentLevel -= PRETTYINDENT_STD;
        appendContextKeyword(context, "", 0, 0, 0);
    }
    else
        appendStringInfoChar(buf, ' ');
}
 
/* ----------
 * get_select_query_def         - Parse back a SELECT parsetree
 * ----------
 */
static void
get_select_query_def(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    bool        force_colno;
    ListCell   *l;
 
    /* Insert the WITH clause if given */
    get_with_clause(query, context);
 
    /* Subroutines may need to consult the SELECT targetlist and windowClause */
    context->targetList = query->targetList;
    context->windowClause = query->windowClause;
 
    /*
     * If the Query node has a setOperations tree, then it's the top level of
     * a UNION/INTERSECT/EXCEPT query; only the WITH, ORDER BY and LIMIT
     * fields are interesting in the top query itself.
     */
    if (query->setOperations)
    {
        get_setop_query(query->setOperations, query, context);
        /* ORDER BY clauses must be simple in this case */
        force_colno = true;
    }
    else
    {
        get_basic_select_query(query, context);
        force_colno = false;
    }
 
    /* Add the ORDER BY clause if given */
    if (query->sortClause != NIL)
    {
        appendContextKeyword(context, " ORDER BY ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
        get_rule_orderby(query->sortClause, query->targetList,
                         force_colno, context);
    }
 
    /*
     * Add the LIMIT/OFFSET clauses if given. If non-default options, use the
     * standard spelling of LIMIT.
     */
    if (query->limitOffset != NULL)
    {
        appendContextKeyword(context, " OFFSET ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
        get_rule_expr(query->limitOffset, context, false);
    }
    if (query->limitCount != NULL)
    {
        if (query->limitOption == LIMIT_OPTION_WITH_TIES)
        {
            appendContextKeyword(context, " FETCH FIRST ",
                                 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
            get_rule_expr(query->limitCount, context, false);
            appendStringInfoString(buf, " ROWS WITH TIES");
        }
        else
        {
            appendContextKeyword(context, " LIMIT ",
                                 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
            if (IsA(query->limitCount, Const) &&
                ((Const *) query->limitCount)->constisnull)
                appendStringInfoString(buf, "ALL");
            else
                get_rule_expr(query->limitCount, context, false);
        }
    }
 
    /* Add FOR [KEY] UPDATE/SHARE clauses if present */
    if (query->hasForUpdate)
    {
        foreach(l, query->rowMarks)
        {
            RowMarkClause *rc = (RowMarkClause *) lfirst(l);
 
            /* don't print implicit clauses */
            if (rc->pushedDown)
                continue;
 
            switch (rc->strength)
            {
                case LCS_NONE:
                    /* we intentionally throw an error for LCS_NONE */
                    elog(ERROR, "unrecognized LockClauseStrength %d",
                         (int) rc->strength);
                    break;
                case LCS_FORKEYSHARE:
                    appendContextKeyword(context, " FOR KEY SHARE",
                                         -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
                    break;
                case LCS_FORSHARE:
                    appendContextKeyword(context, " FOR SHARE",
                                         -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
                    break;
                case LCS_FORNOKEYUPDATE:
                    appendContextKeyword(context, " FOR NO KEY UPDATE",
                                         -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
                    break;
                case LCS_FORUPDATE:
                    appendContextKeyword(context, " FOR UPDATE",
                                         -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
                    break;
            }
 
            appendStringInfo(buf, " OF %s",
                             quote_identifier(get_rtable_name(rc->rti,
                                                              context)));
            if (rc->waitPolicy == LockWaitError)
                appendStringInfoString(buf, " NOWAIT");
            else if (rc->waitPolicy == LockWaitSkip)
                appendStringInfoString(buf, " SKIP LOCKED");
        }
    }
}
 
/*
 * Detect whether query looks like SELECT ... FROM VALUES(),
 * with no need to rename the output columns of the VALUES RTE.
 * If so, return the VALUES RTE.  Otherwise return NULL.
 */
static RangeTblEntry *
get_simple_values_rte(Query *query, TupleDesc resultDesc)
{
    RangeTblEntry *result = NULL;
    ListCell   *lc;
 
    /*
     * We want to detect a match even if the Query also contains OLD or NEW
     * rule RTEs.  So the idea is to scan the rtable and see if there is only
     * one inFromCl RTE that is a VALUES RTE.
     */
    foreach(lc, query->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
 
        if (rte->rtekind == RTE_VALUES && rte->inFromCl)
        {
            if (result)
                return NULL;    /* multiple VALUES (probably not possible) */
            result = rte;
        }
        else if (rte->rtekind == RTE_RELATION && !rte->inFromCl)
            continue;           /* ignore rule entries */
        else
            return NULL;        /* something else -> not simple VALUES */
    }
 
    /*
     * We don't need to check the targetlist in any great detail, because
     * parser/analyze.c will never generate a "bare" VALUES RTE --- they only
     * appear inside auto-generated sub-queries with very restricted
     * structure.  However, DefineView might have modified the tlist by
     * injecting new column aliases, or we might have some other column
     * aliases forced by a resultDesc.  We can only simplify if the RTE's
     * column names match the names that get_target_list() would select.
     */
    if (result)
    {
        ListCell   *lcn;
        int         colno;
 
        if (list_length(query->targetList) != list_length(result->eref->colnames))
            return NULL;        /* this probably cannot happen */
        colno = 0;
        forboth(lc, query->targetList, lcn, result->eref->colnames)
        {
            TargetEntry *tle = (TargetEntry *) lfirst(lc);
            char       *cname = strVal(lfirst(lcn));
            char       *colname;
 
            if (tle->resjunk)
                return NULL;    /* this probably cannot happen */
 
            /* compute name that get_target_list would use for column */
            colno++;
            if (resultDesc && colno <= resultDesc->natts)
                colname = NameStr(TupleDescAttr(resultDesc, colno - 1)->attname);
            else
                colname = tle->resname;
 
            /* does it match the VALUES RTE? */
            if (colname == NULL || strcmp(colname, cname) != 0)
                return NULL;    /* column name has been changed */
        }
    }
 
    return result;
}
 
static void
get_basic_select_query(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    RangeTblEntry *values_rte;
    char       *sep;
    ListCell   *l;
 
    if (PRETTY_INDENT(context))
    {
        context->indentLevel += PRETTYINDENT_STD;
        appendStringInfoChar(buf, ' ');
    }
 
    /*
     * If the query looks like SELECT * FROM (VALUES ...), then print just the
     * VALUES part.  This reverses what transformValuesClause() did at parse
     * time.
     */
    values_rte = get_simple_values_rte(query, context->resultDesc);
    if (values_rte)
    {
        get_values_def(values_rte->values_lists, context);
        return;
    }
 
    /*
     * Build up the query string - first we say SELECT
     */
    if (query->isReturn)
        appendStringInfoString(buf, "RETURN");
    else
        appendStringInfoString(buf, "SELECT");
 
    /* Add the DISTINCT clause if given */
    if (query->distinctClause != NIL)
    {
        if (query->hasDistinctOn)
        {
            appendStringInfoString(buf, " DISTINCT ON (");
            sep = "";
            foreach(l, query->distinctClause)
            {
                SortGroupClause *srt = (SortGroupClause *) lfirst(l);
 
                appendStringInfoString(buf, sep);
                get_rule_sortgroupclause(srt->tleSortGroupRef, query->targetList,
                                         false, context);
                sep = ", ";
            }
            appendStringInfoChar(buf, ')');
        }
        else
            appendStringInfoString(buf, " DISTINCT");
    }
 
    /* Then we tell what to select (the targetlist) */
    get_target_list(query->targetList, context);
 
    /* Add the FROM clause if needed */
    get_from_clause(query, " FROM ", context);
 
    /* Add the WHERE clause if given */
    if (query->jointree->quals != NULL)
    {
        appendContextKeyword(context, " WHERE ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
        get_rule_expr(query->jointree->quals, context, false);
    }
 
    /* Add the GROUP BY clause if given */
    if (query->groupClause != NULL || query->groupingSets != NULL)
    {
        bool        save_ingroupby;
 
        appendContextKeyword(context, " GROUP BY ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
        if (query->groupDistinct)
            appendStringInfoString(buf, "DISTINCT ");
 
        save_ingroupby = context->inGroupBy;
        context->inGroupBy = true;
 
        if (query->groupingSets == NIL)
        {
            sep = "";
            foreach(l, query->groupClause)
            {
                SortGroupClause *grp = (SortGroupClause *) lfirst(l);
 
                appendStringInfoString(buf, sep);
                get_rule_sortgroupclause(grp->tleSortGroupRef, query->targetList,
                                         false, context);
                sep = ", ";
            }
        }
        else
        {
            sep = "";
            foreach(l, query->groupingSets)
            {
                GroupingSet *grp = lfirst(l);
 
                appendStringInfoString(buf, sep);
                get_rule_groupingset(grp, query->targetList, true, context);
                sep = ", ";
            }
        }
 
        context->inGroupBy = save_ingroupby;
    }
 
    /* Add the HAVING clause if given */
    if (query->havingQual != NULL)
    {
        appendContextKeyword(context, " HAVING ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
        get_rule_expr(query->havingQual, context, false);
    }
 
    /* Add the WINDOW clause if needed */
    if (query->windowClause != NIL)
        get_rule_windowclause(query, context);
}
 
/* ----------
 * get_target_list          - Parse back a SELECT target list
 *
 * This is also used for RETURNING lists in INSERT/UPDATE/DELETE/MERGE.
 * ----------
 */
static void
get_target_list(List *targetList, deparse_context *context)
{
    StringInfo  buf = context->buf;
    StringInfoData targetbuf;
    bool        last_was_multiline = false;
    char       *sep;
    int         colno;
    ListCell   *l;
 
    /* we use targetbuf to hold each TLE's text temporarily */
    initStringInfo(&targetbuf);
 
    sep = " ";
    colno = 0;
    foreach(l, targetList)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
        char       *colname;
        char       *attname;
 
        if (tle->resjunk)
            continue;           /* ignore junk entries */
 
        appendStringInfoString(buf, sep);
        sep = ", ";
        colno++;
 
        /*
         * Put the new field text into targetbuf so we can decide after we've
         * got it whether or not it needs to go on a new line.
         */
        resetStringInfo(&targetbuf);
        context->buf = &targetbuf;
 
        /*
         * We special-case Var nodes rather than using get_rule_expr. This is
         * needed because get_rule_expr will display a whole-row Var as
         * "foo.*", which is the preferred notation in most contexts, but at
         * the top level of a SELECT list it's not right (the parser will
         * expand that notation into multiple columns, yielding behavior
         * different from a whole-row Var).  We need to call get_variable
         * directly so that we can tell it to do the right thing, and so that
         * we can get the attribute name which is the default AS label.
         */
        if (tle->expr && (IsA(tle->expr, Var)))
        {
            attname = get_variable((Var *) tle->expr, 0, true, context);
        }
        else
        {
            get_rule_expr((Node *) tle->expr, context, true);
 
            /*
             * When colNamesVisible is true, we should always show the
             * assigned column name explicitly.  Otherwise, show it only if
             * it's not FigureColname's fallback.
             */
            attname = context->colNamesVisible ? NULL : "?column?";
        }
 
        /*
         * Figure out what the result column should be called.  In the context
         * of a view, use the view's tuple descriptor (so as to pick up the
         * effects of any column RENAME that's been done on the view).
         * Otherwise, just use what we can find in the TLE.
         */
        if (context->resultDesc && colno <= context->resultDesc->natts)
            colname = NameStr(TupleDescAttr(context->resultDesc,
                                            colno - 1)->attname);
        else
            colname = tle->resname;
 
        /* Show AS unless the column's name is correct as-is */
        if (colname)            /* resname could be NULL */
        {
            if (attname == NULL || strcmp(attname, colname) != 0)
                appendStringInfo(&targetbuf, " AS %s", quote_identifier(colname));
        }
 
        /* Restore context's output buffer */
        context->buf = buf;
 
        /* Consider line-wrapping if enabled */
        if (PRETTY_INDENT(context) && context->wrapColumn >= 0)
        {
            int         leading_nl_pos;
 
            /* Does the new field start with a new line? */
            if (targetbuf.len > 0 && targetbuf.data[0] == '\n')
                leading_nl_pos = 0;
            else
                leading_nl_pos = -1;
 
            /* If so, we shouldn't add anything */
            if (leading_nl_pos >= 0)
            {
                /* instead, remove any trailing spaces currently in buf */
                removeStringInfoSpaces(buf);
            }
            else
            {
                char       *trailing_nl;
 
                /* Locate the start of the current line in the output buffer */
                trailing_nl = strrchr(buf->data, '\n');
                if (trailing_nl == NULL)
                    trailing_nl = buf->data;
                else
                    trailing_nl++;
 
                /*
                 * Add a newline, plus some indentation, if the new field is
                 * not the first and either the new field would cause an
                 * overflow or the last field used more than one line.
                 */
                if (colno > 1 &&
                    ((strlen(trailing_nl) + targetbuf.len > context->wrapColumn) ||
                     last_was_multiline))
                    appendContextKeyword(context, "", -PRETTYINDENT_STD,
                                         PRETTYINDENT_STD, PRETTYINDENT_VAR);
            }
 
            /* Remember this field's multiline status for next iteration */
            last_was_multiline =
                (strchr(targetbuf.data + leading_nl_pos + 1, '\n') != NULL);
        }
 
        /* Add the new field */
        appendBinaryStringInfo(buf, targetbuf.data, targetbuf.len);
    }
 
    /* clean up */
    pfree(targetbuf.data);
}
 
static void
get_returning_clause(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
 
    if (query->returningList)
    {
        bool        have_with = false;
 
        appendContextKeyword(context, " RETURNING",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
 
        /* Add WITH (OLD/NEW) options, if they're not the defaults */
        if (query->returningOldAlias && strcmp(query->returningOldAlias, "old") != 0)
        {
            appendStringInfo(buf, " WITH (OLD AS %s",
                             quote_identifier(query->returningOldAlias));
            have_with = true;
        }
        if (query->returningNewAlias && strcmp(query->returningNewAlias, "new") != 0)
        {
            if (have_with)
                appendStringInfo(buf, ", NEW AS %s",
                                 quote_identifier(query->returningNewAlias));
            else
            {
                appendStringInfo(buf, " WITH (NEW AS %s",
                                 quote_identifier(query->returningNewAlias));
                have_with = true;
            }
        }
        if (have_with)
            appendStringInfoChar(buf, ')');
 
        /* Add the returning expressions themselves */
        get_target_list(query->returningList, context);
    }
}
 
static void
get_setop_query(Node *setOp, Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    bool        need_paren;
 
    /* Guard against excessively long or deeply-nested queries */
    CHECK_FOR_INTERRUPTS();
    check_stack_depth();
 
    if (IsA(setOp, RangeTblRef))
    {
        RangeTblRef *rtr = (RangeTblRef *) setOp;
        RangeTblEntry *rte = rt_fetch(rtr->rtindex, query->rtable);
        Query      *subquery = rte->subquery;
 
        Assert(subquery != NULL);
 
        /*
         * We need parens if WITH, ORDER BY, FOR UPDATE, or LIMIT; see gram.y.
         * Also add parens if the leaf query contains its own set operations.
         * (That shouldn't happen unless one of the other clauses is also
         * present, see transformSetOperationTree; but let's be safe.)
         */
        need_paren = (subquery->cteList ||
                      subquery->sortClause ||
                      subquery->rowMarks ||
                      subquery->limitOffset ||
                      subquery->limitCount ||
                      subquery->setOperations);
        if (need_paren)
            appendStringInfoChar(buf, '(');
        get_query_def(subquery, buf, context->namespaces,
                      context->resultDesc, context->colNamesVisible,
                      context->prettyFlags, context->wrapColumn,
                      context->indentLevel);
        if (need_paren)
            appendStringInfoChar(buf, ')');
    }
    else if (IsA(setOp, SetOperationStmt))
    {
        SetOperationStmt *op = (SetOperationStmt *) setOp;
        int         subindent;
        bool        save_colnamesvisible;
 
        /*
         * We force parens when nesting two SetOperationStmts, except when the
         * lefthand input is another setop of the same kind.  Syntactically,
         * we could omit parens in rather more cases, but it seems best to use
         * parens to flag cases where the setop operator changes.  If we use
         * parens, we also increase the indentation level for the child query.
         *
         * There are some cases in which parens are needed around a leaf query
         * too, but those are more easily handled at the next level down (see
         * code above).
         */
        if (IsA(op->larg, SetOperationStmt))
        {
            SetOperationStmt *lop = (SetOperationStmt *) op->larg;
 
            if (op->op == lop->op && op->all == lop->all)
                need_paren = false;
            else
                need_paren = true;
        }
        else
            need_paren = false;
 
        if (need_paren)
        {
            appendStringInfoChar(buf, '(');
            subindent = PRETTYINDENT_STD;
            appendContextKeyword(context, "", subindent, 0, 0);
        }
        else
            subindent = 0;
 
        get_setop_query(op->larg, query, context);
 
        if (need_paren)
            appendContextKeyword(context, ") ", -subindent, 0, 0);
        else if (PRETTY_INDENT(context))
            appendContextKeyword(context, "", -subindent, 0, 0);
        else
            appendStringInfoChar(buf, ' ');
 
        switch (op->op)
        {
            case SETOP_UNION:
                appendStringInfoString(buf, "UNION ");
                break;
            case SETOP_INTERSECT:
                appendStringInfoString(buf, "INTERSECT ");
                break;
            case SETOP_EXCEPT:
                appendStringInfoString(buf, "EXCEPT ");
                break;
            default:
                elog(ERROR, "unrecognized set op: %d",
                     (int) op->op);
        }
        if (op->all)
            appendStringInfoString(buf, "ALL ");
 
        /* Always parenthesize if RHS is another setop */
        need_paren = IsA(op->rarg, SetOperationStmt);
 
        /*
         * The indentation code here is deliberately a bit different from that
         * for the lefthand input, because we want the line breaks in
         * different places.
         */
        if (need_paren)
        {
            appendStringInfoChar(buf, '(');
            subindent = PRETTYINDENT_STD;
        }
        else
            subindent = 0;
        appendContextKeyword(context, "", subindent, 0, 0);
 
        /*
         * The output column names of the RHS sub-select don't matter.
         */
        save_colnamesvisible = context->colNamesVisible;
        context->colNamesVisible = false;
 
        get_setop_query(op->rarg, query, context);
 
        context->colNamesVisible = save_colnamesvisible;
 
        if (PRETTY_INDENT(context))
            context->indentLevel -= subindent;
        if (need_paren)
            appendContextKeyword(context, ")", 0, 0, 0);
    }
    else
    {
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(setOp));
    }
}
 
/*
 * Display a sort/group clause.
 *
 * Also returns the expression tree, so caller need not find it again.
 */
static Node *
get_rule_sortgroupclause(Index ref, List *tlist, bool force_colno,
                         deparse_context *context)
{
    StringInfo  buf = context->buf;
    TargetEntry *tle;
    Node       *expr;
 
    tle = get_sortgroupref_tle(ref, tlist);
    expr = (Node *) tle->expr;
 
    /*
     * Use column-number form if requested by caller.  Otherwise, if
     * expression is a constant, force it to be dumped with an explicit cast
     * as decoration --- this is because a simple integer constant is
     * ambiguous (and will be misinterpreted by findTargetlistEntrySQL92()) if
     * we dump it without any decoration.  Similarly, if it's just a Var,
     * there is risk of misinterpretation if the column name is reassigned in
     * the SELECT list, so we may need to force table qualification.  And, if
     * it's anything more complex than a simple Var, then force extra parens
     * around it, to ensure it can't be misinterpreted as a cube() or rollup()
     * construct.
     */
    if (force_colno)
    {
        Assert(!tle->resjunk);
        appendStringInfo(buf, "%d", tle->resno);
    }
    else if (!expr)
         /* do nothing, probably can't happen */ ;
    else if (IsA(expr, Const))
        get_const_expr((Const *) expr, context, 1);
    else if (IsA(expr, Var))
    {
        /* Tell get_variable to check for name conflict */
        bool        save_varinorderby = context->varInOrderBy;
 
        context->varInOrderBy = true;
        (void) get_variable((Var *) expr, 0, false, context);
        context->varInOrderBy = save_varinorderby;
    }
    else
    {
        /*
         * We must force parens for function-like expressions even if
         * PRETTY_PAREN is off, since those are the ones in danger of
         * misparsing. For other expressions we need to force them only if
         * PRETTY_PAREN is on, since otherwise the expression will output them
         * itself. (We can't skip the parens.)
         */
        bool        need_paren = (PRETTY_PAREN(context)
                                  || IsA(expr, FuncExpr)
                                  || IsA(expr, Aggref)
                                  || IsA(expr, WindowFunc)
                                  || IsA(expr, JsonConstructorExpr));
 
        if (need_paren)
            appendStringInfoChar(context->buf, '(');
        get_rule_expr(expr, context, true);
        if (need_paren)
            appendStringInfoChar(context->buf, ')');
    }
 
    return expr;
}
 
/*
 * Display a GroupingSet
 */
static void
get_rule_groupingset(GroupingSet *gset, List *targetlist,
                     bool omit_parens, deparse_context *context)
{
    ListCell   *l;
    StringInfo  buf = context->buf;
    bool        omit_child_parens = true;
    char       *sep = "";
 
    switch (gset->kind)
    {
        case GROUPING_SET_EMPTY:
            appendStringInfoString(buf, "()");
            return;
 
        case GROUPING_SET_SIMPLE:
            {
                if (!omit_parens || list_length(gset->content) != 1)
                    appendStringInfoChar(buf, '(');
 
                foreach(l, gset->content)
                {
                    Index       ref = lfirst_int(l);
 
                    appendStringInfoString(buf, sep);
                    get_rule_sortgroupclause(ref, targetlist,
                                             false, context);
                    sep = ", ";
                }
 
                if (!omit_parens || list_length(gset->content) != 1)
                    appendStringInfoChar(buf, ')');
            }
            return;
 
        case GROUPING_SET_ROLLUP:
            appendStringInfoString(buf, "ROLLUP(");
            break;
        case GROUPING_SET_CUBE:
            appendStringInfoString(buf, "CUBE(");
            break;
        case GROUPING_SET_SETS:
            appendStringInfoString(buf, "GROUPING SETS (");
            omit_child_parens = false;
            break;
    }
 
    foreach(l, gset->content)
    {
        appendStringInfoString(buf, sep);
        get_rule_groupingset(lfirst(l), targetlist, omit_child_parens, context);
        sep = ", ";
    }
 
    appendStringInfoChar(buf, ')');
}
 
/*
 * Display an ORDER BY list.
 */
static void
get_rule_orderby(List *orderList, List *targetList,
                 bool force_colno, deparse_context *context)
{
    StringInfo  buf = context->buf;
    const char *sep;
    ListCell   *l;
 
    sep = "";
    foreach(l, orderList)
    {
        SortGroupClause *srt = (SortGroupClause *) lfirst(l);
        Node       *sortexpr;
        Oid         sortcoltype;
        TypeCacheEntry *typentry;
 
        appendStringInfoString(buf, sep);
        sortexpr = get_rule_sortgroupclause(srt->tleSortGroupRef, targetList,
                                            force_colno, context);
        sortcoltype = exprType(sortexpr);
        /* See whether operator is default < or > for datatype */
        typentry = lookup_type_cache(sortcoltype,
                                     TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
        if (srt->sortop == typentry->lt_opr)
        {
            /* ASC is default, so emit nothing for it */
            if (srt->nulls_first)
                appendStringInfoString(buf, " NULLS FIRST");
        }
        else if (srt->sortop == typentry->gt_opr)
        {
            appendStringInfoString(buf, " DESC");
            /* DESC defaults to NULLS FIRST */
            if (!srt->nulls_first)
                appendStringInfoString(buf, " NULLS LAST");
        }
        else
        {
            appendStringInfo(buf, " USING %s",
                             generate_operator_name(srt->sortop,
                                                    sortcoltype,
                                                    sortcoltype));
            /* be specific to eliminate ambiguity */
            if (srt->nulls_first)
                appendStringInfoString(buf, " NULLS FIRST");
            else
                appendStringInfoString(buf, " NULLS LAST");
        }
        sep = ", ";
    }
}
 
/*
 * Display a WINDOW clause.
 *
 * Note that the windowClause list might contain only anonymous window
 * specifications, in which case we should print nothing here.
 */
static void
get_rule_windowclause(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    const char *sep;
    ListCell   *l;
 
    sep = NULL;
    foreach(l, query->windowClause)
    {
        WindowClause *wc = (WindowClause *) lfirst(l);
 
        if (wc->name == NULL)
            continue;           /* ignore anonymous windows */
 
        if (sep == NULL)
            appendContextKeyword(context, " WINDOW ",
                                 -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
        else
            appendStringInfoString(buf, sep);
 
        appendStringInfo(buf, "%s AS ", quote_identifier(wc->name));
 
        get_rule_windowspec(wc, query->targetList, context);
 
        sep = ", ";
    }
}
 
/*
 * Display a window definition
 */
static void
get_rule_windowspec(WindowClause *wc, List *targetList,
                    deparse_context *context)
{
    StringInfo  buf = context->buf;
    bool        needspace = false;
    const char *sep;
    ListCell   *l;
 
    appendStringInfoChar(buf, '(');
    if (wc->refname)
    {
        appendStringInfoString(buf, quote_identifier(wc->refname));
        needspace = true;
    }
    /* partition clauses are always inherited, so only print if no refname */
    if (wc->partitionClause && !wc->refname)
    {
        if (needspace)
            appendStringInfoChar(buf, ' ');
        appendStringInfoString(buf, "PARTITION BY ");
        sep = "";
        foreach(l, wc->partitionClause)
        {
            SortGroupClause *grp = (SortGroupClause *) lfirst(l);
 
            appendStringInfoString(buf, sep);
            get_rule_sortgroupclause(grp->tleSortGroupRef, targetList,
                                     false, context);
            sep = ", ";
        }
        needspace = true;
    }
    /* print ordering clause only if not inherited */
    if (wc->orderClause && !wc->copiedOrder)
    {
        if (needspace)
            appendStringInfoChar(buf, ' ');
        appendStringInfoString(buf, "ORDER BY ");
        get_rule_orderby(wc->orderClause, targetList, false, context);
        needspace = true;
    }
    /* framing clause is never inherited, so print unless it's default */
    if (wc->frameOptions & FRAMEOPTION_NONDEFAULT)
    {
        if (needspace)
            appendStringInfoChar(buf, ' ');
        get_window_frame_options(wc->frameOptions,
                                 wc->startOffset, wc->endOffset,
                                 context);
    }
    appendStringInfoChar(buf, ')');
}
 
/*
 * Append the description of a window's framing options to context->buf
 */
static void
get_window_frame_options(int frameOptions,
                         Node *startOffset, Node *endOffset,
                         deparse_context *context)
{
    StringInfo  buf = context->buf;
 
    if (frameOptions & FRAMEOPTION_NONDEFAULT)
    {
        if (frameOptions & FRAMEOPTION_RANGE)
            appendStringInfoString(buf, "RANGE ");
        else if (frameOptions & FRAMEOPTION_ROWS)
            appendStringInfoString(buf, "ROWS ");
        else if (frameOptions & FRAMEOPTION_GROUPS)
            appendStringInfoString(buf, "GROUPS ");
        else
            Assert(false);
        if (frameOptions & FRAMEOPTION_BETWEEN)
            appendStringInfoString(buf, "BETWEEN ");
        if (frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING)
            appendStringInfoString(buf, "UNBOUNDED PRECEDING ");
        else if (frameOptions & FRAMEOPTION_START_CURRENT_ROW)
            appendStringInfoString(buf, "CURRENT ROW ");
        else if (frameOptions & FRAMEOPTION_START_OFFSET)
        {
            get_rule_expr(startOffset, context, false);
            if (frameOptions & FRAMEOPTION_START_OFFSET_PRECEDING)
                appendStringInfoString(buf, " PRECEDING ");
            else if (frameOptions & FRAMEOPTION_START_OFFSET_FOLLOWING)
                appendStringInfoString(buf, " FOLLOWING ");
            else
                Assert(false);
        }
        else
            Assert(false);
        if (frameOptions & FRAMEOPTION_BETWEEN)
        {
            appendStringInfoString(buf, "AND ");
            if (frameOptions & FRAMEOPTION_END_UNBOUNDED_FOLLOWING)
                appendStringInfoString(buf, "UNBOUNDED FOLLOWING ");
            else if (frameOptions & FRAMEOPTION_END_CURRENT_ROW)
                appendStringInfoString(buf, "CURRENT ROW ");
            else if (frameOptions & FRAMEOPTION_END_OFFSET)
            {
                get_rule_expr(endOffset, context, false);
                if (frameOptions & FRAMEOPTION_END_OFFSET_PRECEDING)
                    appendStringInfoString(buf, " PRECEDING ");
                else if (frameOptions & FRAMEOPTION_END_OFFSET_FOLLOWING)
                    appendStringInfoString(buf, " FOLLOWING ");
                else
                    Assert(false);
            }
            else
                Assert(false);
        }
        if (frameOptions & FRAMEOPTION_EXCLUDE_CURRENT_ROW)
            appendStringInfoString(buf, "EXCLUDE CURRENT ROW ");
        else if (frameOptions & FRAMEOPTION_EXCLUDE_GROUP)
            appendStringInfoString(buf, "EXCLUDE GROUP ");
        else if (frameOptions & FRAMEOPTION_EXCLUDE_TIES)
            appendStringInfoString(buf, "EXCLUDE TIES ");
        /* we will now have a trailing space; remove it */
        buf->data[--(buf->len)] = '\0';
    }
}
 
/*
 * Return the description of a window's framing options as a palloc'd string
 */
char *
get_window_frame_options_for_explain(int frameOptions,
                                     Node *startOffset, Node *endOffset,
                                     List *dpcontext, bool forceprefix)
{
    StringInfoData buf;
    deparse_context context;
 
    initStringInfo(&buf);
    context.buf = &buf;
    context.namespaces = dpcontext;
    context.resultDesc = NULL;
    context.targetList = NIL;
    context.windowClause = NIL;
    context.varprefix = forceprefix;
    context.prettyFlags = 0;
    context.wrapColumn = WRAP_COLUMN_DEFAULT;
    context.indentLevel = 0;
    context.colNamesVisible = true;
    context.inGroupBy = false;
    context.varInOrderBy = false;
    context.appendparents = NULL;
 
    get_window_frame_options(frameOptions, startOffset, endOffset, &context);
 
    return buf.data;
}
 
/* ----------
 * get_insert_query_def         - Parse back an INSERT parsetree
 * ----------
 */
static void
get_insert_query_def(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    RangeTblEntry *select_rte = NULL;
    RangeTblEntry *values_rte = NULL;
    RangeTblEntry *rte;
    char       *sep;
    ListCell   *l;
    List       *strippedexprs;
 
    /* Insert the WITH clause if given */
    get_with_clause(query, context);
 
    /*
     * If it's an INSERT ... SELECT or multi-row VALUES, there will be a
     * single RTE for the SELECT or VALUES.  Plain VALUES has neither.
     */
    foreach(l, query->rtable)
    {
        rte = (RangeTblEntry *) lfirst(l);
 
        if (rte->rtekind == RTE_SUBQUERY)
        {
            if (select_rte)
                elog(ERROR, "too many subquery RTEs in INSERT");
            select_rte = rte;
        }
 
        if (rte->rtekind == RTE_VALUES)
        {
            if (values_rte)
                elog(ERROR, "too many values RTEs in INSERT");
            values_rte = rte;
        }
    }
    if (select_rte && values_rte)
        elog(ERROR, "both subquery and values RTEs in INSERT");
 
    /*
     * Start the query with INSERT INTO relname
     */
    rte = rt_fetch(query->resultRelation, query->rtable);
    Assert(rte->rtekind == RTE_RELATION);
 
    if (PRETTY_INDENT(context))
    {
        context->indentLevel += PRETTYINDENT_STD;
        appendStringInfoChar(buf, ' ');
    }
    appendStringInfo(buf, "INSERT INTO %s",
                     generate_relation_name(rte->relid, NIL));
 
    /* Print the relation alias, if needed; INSERT requires explicit AS */
    get_rte_alias(rte, query->resultRelation, true, context);
 
    /* always want a space here */
    appendStringInfoChar(buf, ' ');
 
    /*
     * Add the insert-column-names list.  Any indirection decoration needed on
     * the column names can be inferred from the top targetlist.
     */
    strippedexprs = NIL;
    sep = "";
    if (query->targetList)
        appendStringInfoChar(buf, '(');
    foreach(l, query->targetList)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
 
        if (tle->resjunk)
            continue;           /* ignore junk entries */
 
        appendStringInfoString(buf, sep);
        sep = ", ";
 
        /*
         * Put out name of target column; look in the catalogs, not at
         * tle->resname, since resname will fail to track RENAME.
         */
        appendStringInfoString(buf,
                               quote_identifier(get_attname(rte->relid,
                                                            tle->resno,
                                                            false)));
 
        /*
         * Print any indirection needed (subfields or subscripts), and strip
         * off the top-level nodes representing the indirection assignments.
         * Add the stripped expressions to strippedexprs.  (If it's a
         * single-VALUES statement, the stripped expressions are the VALUES to
         * print below.  Otherwise they're just Vars and not really
         * interesting.)
         */
        strippedexprs = lappend(strippedexprs,
                                processIndirection((Node *) tle->expr,
                                                   context));
    }
    if (query->targetList)
        appendStringInfoString(buf, ") ");
 
    if (query->override)
    {
        if (query->override == OVERRIDING_SYSTEM_VALUE)
            appendStringInfoString(buf, "OVERRIDING SYSTEM VALUE ");
        else if (query->override == OVERRIDING_USER_VALUE)
            appendStringInfoString(buf, "OVERRIDING USER VALUE ");
    }
 
    if (select_rte)
    {
        /* Add the SELECT */
        get_query_def(select_rte->subquery, buf, context->namespaces, NULL,
                      false,
                      context->prettyFlags, context->wrapColumn,
                      context->indentLevel);
    }
    else if (values_rte)
    {
        /* Add the multi-VALUES expression lists */
        get_values_def(values_rte->values_lists, context);
    }
    else if (strippedexprs)
    {
        /* Add the single-VALUES expression list */
        appendContextKeyword(context, "VALUES (",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
        get_rule_list_toplevel(strippedexprs, context, false);
        appendStringInfoChar(buf, ')');
    }
    else
    {
        /* No expressions, so it must be DEFAULT VALUES */
        appendStringInfoString(buf, "DEFAULT VALUES");
    }
 
    /* Add ON CONFLICT if present */
    if (query->onConflict)
    {
        OnConflictExpr *confl = query->onConflict;
 
        appendStringInfoString(buf, " ON CONFLICT");
 
        if (confl->arbiterElems)
        {
            /* Add the single-VALUES expression list */
            appendStringInfoChar(buf, '(');
            get_rule_expr((Node *) confl->arbiterElems, context, false);
            appendStringInfoChar(buf, ')');
 
            /* Add a WHERE clause (for partial indexes) if given */
            if (confl->arbiterWhere != NULL)
            {
                bool        save_varprefix;
 
                /*
                 * Force non-prefixing of Vars, since parser assumes that they
                 * belong to target relation.  WHERE clause does not use
                 * InferenceElem, so this is separately required.
                 */
                save_varprefix = context->varprefix;
                context->varprefix = false;
 
                appendContextKeyword(context, " WHERE ",
                                     -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
                get_rule_expr(confl->arbiterWhere, context, false);
 
                context->varprefix = save_varprefix;
            }
        }
        else if (OidIsValid(confl->constraint))
        {
            char       *constraint = get_constraint_name(confl->constraint);
 
            if (!constraint)
                elog(ERROR, "cache lookup failed for constraint %u",
                     confl->constraint);
            appendStringInfo(buf, " ON CONSTRAINT %s",
                             quote_identifier(constraint));
        }
 
        if (confl->action == ONCONFLICT_NOTHING)
        {
            appendStringInfoString(buf, " DO NOTHING");
        }
        else
        {
            appendStringInfoString(buf, " DO UPDATE SET ");
            /* Deparse targetlist */
            get_update_query_targetlist_def(query, confl->onConflictSet,
                                            context, rte);
 
            /* Add a WHERE clause if given */
            if (confl->onConflictWhere != NULL)
            {
                appendContextKeyword(context, " WHERE ",
                                     -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
                get_rule_expr(confl->onConflictWhere, context, false);
            }
        }
    }
 
    /* Add RETURNING if present */
    if (query->returningList)
        get_returning_clause(query, context);
}
 
 
/* ----------
 * get_update_query_def         - Parse back an UPDATE parsetree
 * ----------
 */
static void
get_update_query_def(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    RangeTblEntry *rte;
 
    /* Insert the WITH clause if given */
    get_with_clause(query, context);
 
    /*
     * Start the query with UPDATE relname SET
     */
    rte = rt_fetch(query->resultRelation, query->rtable);
    Assert(rte->rtekind == RTE_RELATION);
    if (PRETTY_INDENT(context))
    {
        appendStringInfoChar(buf, ' ');
        context->indentLevel += PRETTYINDENT_STD;
    }
    appendStringInfo(buf, "UPDATE %s%s",
                     only_marker(rte),
                     generate_relation_name(rte->relid, NIL));
 
    /* Print the relation alias, if needed */
    get_rte_alias(rte, query->resultRelation, false, context);
 
    appendStringInfoString(buf, " SET ");
 
    /* Deparse targetlist */
    get_update_query_targetlist_def(query, query->targetList, context, rte);
 
    /* Add the FROM clause if needed */
    get_from_clause(query, " FROM ", context);
 
    /* Add a WHERE clause if given */
    if (query->jointree->quals != NULL)
    {
        appendContextKeyword(context, " WHERE ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
        get_rule_expr(query->jointree->quals, context, false);
    }
 
    /* Add RETURNING if present */
    if (query->returningList)
        get_returning_clause(query, context);
}
 
 
/* ----------
 * get_update_query_targetlist_def          - Parse back an UPDATE targetlist
 * ----------
 */
static void
get_update_query_targetlist_def(Query *query, List *targetList,
                                deparse_context *context, RangeTblEntry *rte)
{
    StringInfo  buf = context->buf;
    ListCell   *l;
    ListCell   *next_ma_cell;
    int         remaining_ma_columns;
    const char *sep;
    SubLink    *cur_ma_sublink;
    List       *ma_sublinks;
 
    /*
     * Prepare to deal with MULTIEXPR assignments: collect the source SubLinks
     * into a list.  We expect them to appear, in ID order, in resjunk tlist
     * entries.
     */
    ma_sublinks = NIL;
    if (query->hasSubLinks)     /* else there can't be any */
    {
        foreach(l, targetList)
        {
            TargetEntry *tle = (TargetEntry *) lfirst(l);
 
            if (tle->resjunk && IsA(tle->expr, SubLink))
            {
                SubLink    *sl = (SubLink *) tle->expr;
 
                if (sl->subLinkType == MULTIEXPR_SUBLINK)
                {
                    ma_sublinks = lappend(ma_sublinks, sl);
                    Assert(sl->subLinkId == list_length(ma_sublinks));
                }
            }
        }
    }
    next_ma_cell = list_head(ma_sublinks);
    cur_ma_sublink = NULL;
    remaining_ma_columns = 0;
 
    /* Add the comma separated list of 'attname = value' */
    sep = "";
    foreach(l, targetList)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
        Node       *expr;
 
        if (tle->resjunk)
            continue;           /* ignore junk entries */
 
        /* Emit separator (OK whether we're in multiassignment or not) */
        appendStringInfoString(buf, sep);
        sep = ", ";
 
        /*
         * Check to see if we're starting a multiassignment group: if so,
         * output a left paren.
         */
        if (next_ma_cell != NULL && cur_ma_sublink == NULL)
        {
            /*
             * We must dig down into the expr to see if it's a PARAM_MULTIEXPR
             * Param.  That could be buried under FieldStores and
             * SubscriptingRefs and CoerceToDomains (cf processIndirection()),
             * and underneath those there could be an implicit type coercion.
             * Because we would ignore implicit type coercions anyway, we
             * don't need to be as careful as processIndirection() is about
             * descending past implicit CoerceToDomains.
             */
            expr = (Node *) tle->expr;
            while (expr)
            {
                if (IsA(expr, FieldStore))
                {
                    FieldStore *fstore = (FieldStore *) expr;
 
                    expr = (Node *) linitial(fstore->newvals);
                }
                else if (IsA(expr, SubscriptingRef))
                {
                    SubscriptingRef *sbsref = (SubscriptingRef *) expr;
 
                    if (sbsref->refassgnexpr == NULL)
                        break;
 
                    expr = (Node *) sbsref->refassgnexpr;
                }
                else if (IsA(expr, CoerceToDomain))
                {
                    CoerceToDomain *cdomain = (CoerceToDomain *) expr;
 
                    if (cdomain->coercionformat != COERCE_IMPLICIT_CAST)
                        break;
                    expr = (Node *) cdomain->arg;
                }
                else
                    break;
            }
            expr = strip_implicit_coercions(expr);
 
            if (expr && IsA(expr, Param) &&
                ((Param *) expr)->paramkind == PARAM_MULTIEXPR)
            {
                cur_ma_sublink = (SubLink *) lfirst(next_ma_cell);
                next_ma_cell = lnext(ma_sublinks, next_ma_cell);
                remaining_ma_columns = count_nonjunk_tlist_entries(((Query *) cur_ma_sublink->subselect)->targetList);
                Assert(((Param *) expr)->paramid ==
                       ((cur_ma_sublink->subLinkId << 16) | 1));
                appendStringInfoChar(buf, '(');
            }
        }
 
        /*
         * Put out name of target column; look in the catalogs, not at
         * tle->resname, since resname will fail to track RENAME.
         */
        appendStringInfoString(buf,
                               quote_identifier(get_attname(rte->relid,
                                                            tle->resno,
                                                            false)));
 
        /*
         * Print any indirection needed (subfields or subscripts), and strip
         * off the top-level nodes representing the indirection assignments.
         */
        expr = processIndirection((Node *) tle->expr, context);
 
        /*
         * If we're in a multiassignment, skip printing anything more, unless
         * this is the last column; in which case, what we print should be the
         * sublink, not the Param.
         */
        if (cur_ma_sublink != NULL)
        {
            if (--remaining_ma_columns > 0)
                continue;       /* not the last column of multiassignment */
            appendStringInfoChar(buf, ')');
            expr = (Node *) cur_ma_sublink;
            cur_ma_sublink = NULL;
        }
 
        appendStringInfoString(buf, " = ");
 
        get_rule_expr(expr, context, false);
    }
}
 
 
/* ----------
 * get_delete_query_def         - Parse back a DELETE parsetree
 * ----------
 */
static void
get_delete_query_def(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    RangeTblEntry *rte;
 
    /* Insert the WITH clause if given */
    get_with_clause(query, context);
 
    /*
     * Start the query with DELETE FROM relname
     */
    rte = rt_fetch(query->resultRelation, query->rtable);
    Assert(rte->rtekind == RTE_RELATION);
    if (PRETTY_INDENT(context))
    {
        appendStringInfoChar(buf, ' ');
        context->indentLevel += PRETTYINDENT_STD;
    }
    appendStringInfo(buf, "DELETE FROM %s%s",
                     only_marker(rte),
                     generate_relation_name(rte->relid, NIL));
 
    /* Print the relation alias, if needed */
    get_rte_alias(rte, query->resultRelation, false, context);
 
    /* Add the USING clause if given */
    get_from_clause(query, " USING ", context);
 
    /* Add a WHERE clause if given */
    if (query->jointree->quals != NULL)
    {
        appendContextKeyword(context, " WHERE ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
        get_rule_expr(query->jointree->quals, context, false);
    }
 
    /* Add RETURNING if present */
    if (query->returningList)
        get_returning_clause(query, context);
}
 
 
/* ----------
 * get_merge_query_def              - Parse back a MERGE parsetree
 * ----------
 */
static void
get_merge_query_def(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    RangeTblEntry *rte;
    ListCell   *lc;
    bool        haveNotMatchedBySource;
 
    /* Insert the WITH clause if given */
    get_with_clause(query, context);
 
    /*
     * Start the query with MERGE INTO relname
     */
    rte = rt_fetch(query->resultRelation, query->rtable);
    Assert(rte->rtekind == RTE_RELATION);
    if (PRETTY_INDENT(context))
    {
        appendStringInfoChar(buf, ' ');
        context->indentLevel += PRETTYINDENT_STD;
    }
    appendStringInfo(buf, "MERGE INTO %s%s",
                     only_marker(rte),
                     generate_relation_name(rte->relid, NIL));
 
    /* Print the relation alias, if needed */
    get_rte_alias(rte, query->resultRelation, false, context);
 
    /* Print the source relation and join clause */
    get_from_clause(query, " USING ", context);
    appendContextKeyword(context, " ON ",
                         -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
    get_rule_expr(query->mergeJoinCondition, context, false);
 
    /*
     * Test for any NOT MATCHED BY SOURCE actions.  If there are none, then
     * any NOT MATCHED BY TARGET actions are output as "WHEN NOT MATCHED", per
     * SQL standard.  Otherwise, we have a non-SQL-standard query, so output
     * "BY SOURCE" / "BY TARGET" qualifiers for all NOT MATCHED actions, to be
     * more explicit.
     */
    haveNotMatchedBySource = false;
    foreach(lc, query->mergeActionList)
    {
        MergeAction *action = lfirst_node(MergeAction, lc);
 
        if (action->matchKind == MERGE_WHEN_NOT_MATCHED_BY_SOURCE)
        {
            haveNotMatchedBySource = true;
            break;
        }
    }
 
    /* Print each merge action */
    foreach(lc, query->mergeActionList)
    {
        MergeAction *action = lfirst_node(MergeAction, lc);
 
        appendContextKeyword(context, " WHEN ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
        switch (action->matchKind)
        {
            case MERGE_WHEN_MATCHED:
                appendStringInfoString(buf, "MATCHED");
                break;
            case MERGE_WHEN_NOT_MATCHED_BY_SOURCE:
                appendStringInfoString(buf, "NOT MATCHED BY SOURCE");
                break;
            case MERGE_WHEN_NOT_MATCHED_BY_TARGET:
                if (haveNotMatchedBySource)
                    appendStringInfoString(buf, "NOT MATCHED BY TARGET");
                else
                    appendStringInfoString(buf, "NOT MATCHED");
                break;
            default:
                elog(ERROR, "unrecognized matchKind: %d",
                     (int) action->matchKind);
        }
 
        if (action->qual)
        {
            appendContextKeyword(context, " AND ",
                                 -PRETTYINDENT_STD, PRETTYINDENT_STD, 3);
            get_rule_expr(action->qual, context, false);
        }
        appendContextKeyword(context, " THEN ",
                             -PRETTYINDENT_STD, PRETTYINDENT_STD, 3);
 
        if (action->commandType == CMD_INSERT)
        {
            /* This generally matches get_insert_query_def() */
            List       *strippedexprs = NIL;
            const char *sep = "";
            ListCell   *lc2;
 
            appendStringInfoString(buf, "INSERT");
 
            if (action->targetList)
                appendStringInfoString(buf, " (");
            foreach(lc2, action->targetList)
            {
                TargetEntry *tle = (TargetEntry *) lfirst(lc2);
 
                Assert(!tle->resjunk);
 
                appendStringInfoString(buf, sep);
                sep = ", ";
 
                appendStringInfoString(buf,
                                       quote_identifier(get_attname(rte->relid,
                                                                    tle->resno,
                                                                    false)));
                strippedexprs = lappend(strippedexprs,
                                        processIndirection((Node *) tle->expr,
                                                           context));
            }
            if (action->targetList)
                appendStringInfoChar(buf, ')');
 
            if (action->override)
            {
                if (action->override == OVERRIDING_SYSTEM_VALUE)
                    appendStringInfoString(buf, " OVERRIDING SYSTEM VALUE");
                else if (action->override == OVERRIDING_USER_VALUE)
                    appendStringInfoString(buf, " OVERRIDING USER VALUE");
            }
 
            if (strippedexprs)
            {
                appendContextKeyword(context, " VALUES (",
                                     -PRETTYINDENT_STD, PRETTYINDENT_STD, 4);
                get_rule_list_toplevel(strippedexprs, context, false);
                appendStringInfoChar(buf, ')');
            }
            else
                appendStringInfoString(buf, " DEFAULT VALUES");
        }
        else if (action->commandType == CMD_UPDATE)
        {
            appendStringInfoString(buf, "UPDATE SET ");
            get_update_query_targetlist_def(query, action->targetList,
                                            context, rte);
        }
        else if (action->commandType == CMD_DELETE)
            appendStringInfoString(buf, "DELETE");
        else if (action->commandType == CMD_NOTHING)
            appendStringInfoString(buf, "DO NOTHING");
    }
 
    /* Add RETURNING if present */
    if (query->returningList)
        get_returning_clause(query, context);
}
 
 
/* ----------
 * get_utility_query_def            - Parse back a UTILITY parsetree
 * ----------
 */
static void
get_utility_query_def(Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
 
    if (query->utilityStmt && IsA(query->utilityStmt, NotifyStmt))
    {
        NotifyStmt *stmt = (NotifyStmt *) query->utilityStmt;
 
        appendContextKeyword(context, "",
                             0, PRETTYINDENT_STD, 1);
        appendStringInfo(buf, "NOTIFY %s",
                         quote_identifier(stmt->conditionname));
        if (stmt->payload)
        {
            appendStringInfoString(buf, ", ");
            simple_quote_literal(buf, stmt->payload);
        }
    }
    else
    {
        /* Currently only NOTIFY utility commands can appear in rules */
        elog(ERROR, "unexpected utility statement type");
    }
}
 
/*
 * Display a Var appropriately.
 *
 * In some cases (currently only when recursing into an unnamed join)
 * the Var's varlevelsup has to be interpreted with respect to a context
 * above the current one; levelsup indicates the offset.
 *
 * If istoplevel is true, the Var is at the top level of a SELECT's
 * targetlist, which means we need special treatment of whole-row Vars.
 * Instead of the normal "tab.*", we'll print "tab.*::typename", which is a
 * dirty hack to prevent "tab.*" from being expanded into multiple columns.
 * (The parser will strip the useless coercion, so no inefficiency is added in
 * dump and reload.)  We used to print just "tab" in such cases, but that is
 * ambiguous and will yield the wrong result if "tab" is also a plain column
 * name in the query.
 *
 * Returns the attname of the Var, or NULL if the Var has no attname (because
 * it is a whole-row Var or a subplan output reference).
 */
static char *
get_variable(Var *var, int levelsup, bool istoplevel, deparse_context *context)
{
    StringInfo  buf = context->buf;
    RangeTblEntry *rte;
    AttrNumber  attnum;
    int         netlevelsup;
    deparse_namespace *dpns;
    int         varno;
    AttrNumber  varattno;
    deparse_columns *colinfo;
    char       *refname;
    char       *attname;
    bool        need_prefix;
 
    /* Find appropriate nesting depth */
    netlevelsup = var->varlevelsup + levelsup;
    if (netlevelsup >= list_length(context->namespaces))
        elog(ERROR, "bogus varlevelsup: %d offset %d",
             var->varlevelsup, levelsup);
    dpns = (deparse_namespace *) list_nth(context->namespaces,
                                          netlevelsup);
 
    /*
     * If we have a syntactic referent for the Var, and we're working from a
     * parse tree, prefer to use the syntactic referent.  Otherwise, fall back
     * on the semantic referent.  (Forcing use of the semantic referent when
     * printing plan trees is a design choice that's perhaps more motivated by
     * backwards compatibility than anything else.  But it does have the
     * advantage of making plans more explicit.)
     */
    if (var->varnosyn > 0 && dpns->plan == NULL)
    {
        varno = var->varnosyn;
        varattno = var->varattnosyn;
    }
    else
    {
        varno = var->varno;
        varattno = var->varattno;
    }
 
    /*
     * Try to find the relevant RTE in this rtable.  In a plan tree, it's
     * likely that varno is OUTER_VAR or INNER_VAR, in which case we must dig
     * down into the subplans, or INDEX_VAR, which is resolved similarly. Also
     * find the aliases previously assigned for this RTE.
     */
    if (varno >= 1 && varno <= list_length(dpns->rtable))
    {
        /*
         * We might have been asked to map child Vars to some parent relation.
         */
        if (context->appendparents && dpns->appendrels)
        {
            int         pvarno = varno;
            AttrNumber  pvarattno = varattno;
            AppendRelInfo *appinfo = dpns->appendrels[pvarno];
            bool        found = false;
 
            /* Only map up to inheritance parents, not UNION ALL appendrels */
            while (appinfo &&
                   rt_fetch(appinfo->parent_relid,
                            dpns->rtable)->rtekind == RTE_RELATION)
            {
                found = false;
                if (pvarattno > 0)  /* system columns stay as-is */
                {
                    if (pvarattno > appinfo->num_child_cols)
                        break;  /* safety check */
                    pvarattno = appinfo->parent_colnos[pvarattno - 1];
                    if (pvarattno == 0)
                        break;  /* Var is local to child */
                }
 
                pvarno = appinfo->parent_relid;
                found = true;
 
                /* If the parent is itself a child, continue up. */
                Assert(pvarno > 0 && pvarno <= list_length(dpns->rtable));
                appinfo = dpns->appendrels[pvarno];
            }
 
            /*
             * If we found an ancestral rel, and that rel is included in
             * appendparents, print that column not the original one.
             */
            if (found && bms_is_member(pvarno, context->appendparents))
            {
                varno = pvarno;
                varattno = pvarattno;
            }
        }
 
        rte = rt_fetch(varno, dpns->rtable);
 
        /* might be returning old/new column value */
        if (var->varreturningtype == VAR_RETURNING_OLD)
            refname = dpns->ret_old_alias;
        else if (var->varreturningtype == VAR_RETURNING_NEW)
            refname = dpns->ret_new_alias;
        else
            refname = (char *) list_nth(dpns->rtable_names, varno - 1);
 
        colinfo = deparse_columns_fetch(varno, dpns);
        attnum = varattno;
    }
    else
    {
        resolve_special_varno((Node *) var, context,
                              get_special_variable, NULL);
        return NULL;
    }
 
    /*
     * The planner will sometimes emit Vars referencing resjunk elements of a
     * subquery's target list (this is currently only possible if it chooses
     * to generate a "physical tlist" for a SubqueryScan or CteScan node).
     * Although we prefer to print subquery-referencing Vars using the
     * subquery's alias, that's not possible for resjunk items since they have
     * no alias.  So in that case, drill down to the subplan and print the
     * contents of the referenced tlist item.  This works because in a plan
     * tree, such Vars can only occur in a SubqueryScan or CteScan node, and
     * we'll have set dpns->inner_plan to reference the child plan node.
     */
    if ((rte->rtekind == RTE_SUBQUERY || rte->rtekind == RTE_CTE) &&
        attnum > list_length(rte->eref->colnames) &&
        dpns->inner_plan)
    {
        TargetEntry *tle;
        deparse_namespace save_dpns;
 
        tle = get_tle_by_resno(dpns->inner_tlist, attnum);
        if (!tle)
            elog(ERROR, "invalid attnum %d for relation \"%s\"",
                 attnum, rte->eref->aliasname);
 
        Assert(netlevelsup == 0);
        push_child_plan(dpns, dpns->inner_plan, &save_dpns);
 
        /*
         * Force parentheses because our caller probably assumed a Var is a
         * simple expression.
         */
        if (!IsA(tle->expr, Var))
            appendStringInfoChar(buf, '(');
        get_rule_expr((Node *) tle->expr, context, true);
        if (!IsA(tle->expr, Var))
            appendStringInfoChar(buf, ')');
 
        pop_child_plan(dpns, &save_dpns);
        return NULL;
    }
 
    /*
     * If it's an unnamed join, look at the expansion of the alias variable.
     * If it's a simple reference to one of the input vars, then recursively
     * print the name of that var instead.  When it's not a simple reference,
     * we have to just print the unqualified join column name.  (This can only
     * happen with "dangerous" merged columns in a JOIN USING; we took pains
     * previously to make the unqualified column name unique in such cases.)
     *
     * This wouldn't work in decompiling plan trees, because we don't store
     * joinaliasvars lists after planning; but a plan tree should never
     * contain a join alias variable.
     */
    if (rte->rtekind == RTE_JOIN && rte->alias == NULL)
    {
        if (rte->joinaliasvars == NIL)
            elog(ERROR, "cannot decompile join alias var in plan tree");
        if (attnum > 0)
        {
            Var        *aliasvar;
 
            aliasvar = (Var *) list_nth(rte->joinaliasvars, attnum - 1);
            /* we intentionally don't strip implicit coercions here */
            if (aliasvar && IsA(aliasvar, Var))
            {
                return get_variable(aliasvar, var->varlevelsup + levelsup,
                                    istoplevel, context);
            }
        }
 
        /*
         * Unnamed join has no refname.  (Note: since it's unnamed, there is
         * no way the user could have referenced it to create a whole-row Var
         * for it.  So we don't have to cover that case below.)
         */
        Assert(refname == NULL);
    }
 
    if (attnum == InvalidAttrNumber)
        attname = NULL;
    else if (attnum > 0)
    {
        /* Get column name to use from the colinfo struct */
        if (attnum > colinfo->num_cols)
            elog(ERROR, "invalid attnum %d for relation \"%s\"",
                 attnum, rte->eref->aliasname);
        attname = colinfo->colnames[attnum - 1];
 
        /*
         * If we find a Var referencing a dropped column, it seems better to
         * print something (anything) than to fail.  In general this should
         * not happen, but it used to be possible for some cases involving
         * functions returning named composite types, and perhaps there are
         * still bugs out there.
         */
        if (attname == NULL)
            attname = "?dropped?column?";
    }
    else
    {
        /* System column - name is fixed, get it from the catalog */
        attname = get_rte_attribute_name(rte, attnum);
    }
 
    need_prefix = (context->varprefix || attname == NULL ||
                   var->varreturningtype != VAR_RETURNING_DEFAULT);
 
    /*
     * If we're considering a plain Var in an ORDER BY (but not GROUP BY)
     * clause, we may need to add a table-name prefix to prevent
     * findTargetlistEntrySQL92 from misinterpreting the name as an
     * output-column name.  To avoid cluttering the output with unnecessary
     * prefixes, do so only if there is a name match to a SELECT tlist item
     * that is different from the Var.
     */
    if (context->varInOrderBy && !context->inGroupBy && !need_prefix)
    {
        int         colno = 0;
 
        foreach_node(TargetEntry, tle, context->targetList)
        {
            char       *colname;
 
            if (tle->resjunk)
                continue;       /* ignore junk entries */
            colno++;
 
            /* This must match colname-choosing logic in get_target_list() */
            if (context->resultDesc && colno <= context->resultDesc->natts)
                colname = NameStr(TupleDescAttr(context->resultDesc,
                                                colno - 1)->attname);
            else
                colname = tle->resname;
 
            if (colname && strcmp(colname, attname) == 0 &&
                !equal(var, tle->expr))
            {
                need_prefix = true;
                break;
            }
        }
    }
 
    if (refname && need_prefix)
    {
        appendStringInfoString(buf, quote_identifier(refname));
        appendStringInfoChar(buf, '.');
    }
    if (attname)
        appendStringInfoString(buf, quote_identifier(attname));
    else
    {
        appendStringInfoChar(buf, '*');
        if (istoplevel)
            appendStringInfo(buf, "::%s",
                             format_type_with_typemod(var->vartype,
                                                      var->vartypmod));
    }
 
    return attname;
}
 
/*
 * Deparse a Var which references OUTER_VAR, INNER_VAR, or INDEX_VAR.  This
 * routine is actually a callback for resolve_special_varno, which handles
 * finding the correct TargetEntry.  We get the expression contained in that
 * TargetEntry and just need to deparse it, a job we can throw back on
 * get_rule_expr.
 */
static void
get_special_variable(Node *node, deparse_context *context, void *callback_arg)
{
    StringInfo  buf = context->buf;
 
    /*
     * For a non-Var referent, force parentheses because our caller probably
     * assumed a Var is a simple expression.
     */
    if (!IsA(node, Var))
        appendStringInfoChar(buf, '(');
    get_rule_expr(node, context, true);
    if (!IsA(node, Var))
        appendStringInfoChar(buf, ')');
}
 
/*
 * Chase through plan references to special varnos (OUTER_VAR, INNER_VAR,
 * INDEX_VAR) until we find a real Var or some kind of non-Var node; then,
 * invoke the callback provided.
 */
static void
resolve_special_varno(Node *node, deparse_context *context,
                      rsv_callback callback, void *callback_arg)
{
    Var        *var;
    deparse_namespace *dpns;
 
    /* This function is recursive, so let's be paranoid. */
    check_stack_depth();
 
    /* If it's not a Var, invoke the callback. */
    if (!IsA(node, Var))
    {
        (*callback) (node, context, callback_arg);
        return;
    }
 
    /* Find appropriate nesting depth */
    var = (Var *) node;
    dpns = (deparse_namespace *) list_nth(context->namespaces,
                                          var->varlevelsup);
 
    /*
     * If varno is special, recurse.  (Don't worry about varnosyn; if we're
     * here, we already decided not to use that.)
     */
    if (var->varno == OUTER_VAR && dpns->outer_tlist)
    {
        TargetEntry *tle;
        deparse_namespace save_dpns;
        Bitmapset  *save_appendparents;
 
        tle = get_tle_by_resno(dpns->outer_tlist, var->varattno);
        if (!tle)
            elog(ERROR, "bogus varattno for OUTER_VAR var: %d", var->varattno);
 
        /*
         * If we're descending to the first child of an Append or MergeAppend,
         * update appendparents.  This will affect deparsing of all Vars
         * appearing within the eventually-resolved subexpression.
         */
        save_appendparents = context->appendparents;
 
        if (IsA(dpns->plan, Append))
            context->appendparents = bms_union(context->appendparents,
                                               ((Append *) dpns->plan)->apprelids);
        else if (IsA(dpns->plan, MergeAppend))
            context->appendparents = bms_union(context->appendparents,
                                               ((MergeAppend *) dpns->plan)->apprelids);
 
        push_child_plan(dpns, dpns->outer_plan, &save_dpns);
        resolve_special_varno((Node *) tle->expr, context,
                              callback, callback_arg);
        pop_child_plan(dpns, &save_dpns);
        context->appendparents = save_appendparents;
        return;
    }
    else if (var->varno == INNER_VAR && dpns->inner_tlist)
    {
        TargetEntry *tle;
        deparse_namespace save_dpns;
 
        tle = get_tle_by_resno(dpns->inner_tlist, var->varattno);
        if (!tle)
            elog(ERROR, "bogus varattno for INNER_VAR var: %d", var->varattno);
 
        push_child_plan(dpns, dpns->inner_plan, &save_dpns);
        resolve_special_varno((Node *) tle->expr, context,
                              callback, callback_arg);
        pop_child_plan(dpns, &save_dpns);
        return;
    }
    else if (var->varno == INDEX_VAR && dpns->index_tlist)
    {
        TargetEntry *tle;
 
        tle = get_tle_by_resno(dpns->index_tlist, var->varattno);
        if (!tle)
            elog(ERROR, "bogus varattno for INDEX_VAR var: %d", var->varattno);
 
        resolve_special_varno((Node *) tle->expr, context,
                              callback, callback_arg);
        return;
    }
    else if (var->varno < 1 || var->varno > list_length(dpns->rtable))
        elog(ERROR, "bogus varno: %d", var->varno);
 
    /* Not special.  Just invoke the callback. */
    (*callback) (node, context, callback_arg);
}
 
/*
 * Get the name of a field of an expression of composite type.  The
 * expression is usually a Var, but we handle other cases too.
 *
 * levelsup is an extra offset to interpret the Var's varlevelsup correctly.
 *
 * This is fairly straightforward when the expression has a named composite
 * type; we need only look up the type in the catalogs.  However, the type
 * could also be RECORD.  Since no actual table or view column is allowed to
 * have type RECORD, a Var of type RECORD must refer to a JOIN or FUNCTION RTE
 * or to a subquery output.  We drill down to find the ultimate defining
 * expression and attempt to infer the field name from it.  We ereport if we
 * can't determine the name.
 *
 * Similarly, a PARAM of type RECORD has to refer to some expression of
 * a determinable composite type.
 */
static const char *
get_name_for_var_field(Var *var, int fieldno,
                       int levelsup, deparse_context *context)
{
    RangeTblEntry *rte;
    AttrNumber  attnum;
    int         netlevelsup;
    deparse_namespace *dpns;
    int         varno;
    AttrNumber  varattno;
    TupleDesc   tupleDesc;
    Node       *expr;
 
    /*
     * If it's a RowExpr that was expanded from a whole-row Var, use the
     * column names attached to it.  (We could let get_expr_result_tupdesc()
     * handle this, but it's much cheaper to just pull out the name we need.)
     */
    if (IsA(var, RowExpr))
    {
        RowExpr    *r = (RowExpr *) var;
 
        if (fieldno > 0 && fieldno <= list_length(r->colnames))
            return strVal(list_nth(r->colnames, fieldno - 1));
    }
 
    /*
     * If it's a Param of type RECORD, try to find what the Param refers to.
     */
    if (IsA(var, Param))
    {
        Param      *param = (Param *) var;
        ListCell   *ancestor_cell;
 
        expr = find_param_referent(param, context, &dpns, &ancestor_cell);
        if (expr)
        {
            /* Found a match, so recurse to decipher the field name */
            deparse_namespace save_dpns;
            const char *result;
 
            push_ancestor_plan(dpns, ancestor_cell, &save_dpns);
            result = get_name_for_var_field((Var *) expr, fieldno,
                                            0, context);
            pop_ancestor_plan(dpns, &save_dpns);
            return result;
        }
    }
 
    /*
     * If it's a Var of type RECORD, we have to find what the Var refers to;
     * if not, we can use get_expr_result_tupdesc().
     */
    if (!IsA(var, Var) ||
        var->vartype != RECORDOID)
    {
        tupleDesc = get_expr_result_tupdesc((Node *) var, false);
        /* Got the tupdesc, so we can extract the field name */
        Assert(fieldno >= 1 && fieldno <= tupleDesc->natts);
        return NameStr(TupleDescAttr(tupleDesc, fieldno - 1)->attname);
    }
 
    /* Find appropriate nesting depth */
    netlevelsup = var->varlevelsup + levelsup;
    if (netlevelsup >= list_length(context->namespaces))
        elog(ERROR, "bogus varlevelsup: %d offset %d",
             var->varlevelsup, levelsup);
    dpns = (deparse_namespace *) list_nth(context->namespaces,
                                          netlevelsup);
 
    /*
     * If we have a syntactic referent for the Var, and we're working from a
     * parse tree, prefer to use the syntactic referent.  Otherwise, fall back
     * on the semantic referent.  (See comments in get_variable().)
     */
    if (var->varnosyn > 0 && dpns->plan == NULL)
    {
        varno = var->varnosyn;
        varattno = var->varattnosyn;
    }
    else
    {
        varno = var->varno;
        varattno = var->varattno;
    }
 
    /*
     * Try to find the relevant RTE in this rtable.  In a plan tree, it's
     * likely that varno is OUTER_VAR or INNER_VAR, in which case we must dig
     * down into the subplans, or INDEX_VAR, which is resolved similarly.
     *
     * Note: unlike get_variable and resolve_special_varno, we need not worry
     * about inheritance mapping: a child Var should have the same datatype as
     * its parent, and here we're really only interested in the Var's type.
     */
    if (varno >= 1 && varno <= list_length(dpns->rtable))
    {
        rte = rt_fetch(varno, dpns->rtable);
        attnum = varattno;
    }
    else if (varno == OUTER_VAR && dpns->outer_tlist)
    {
        TargetEntry *tle;
        deparse_namespace save_dpns;
        const char *result;
 
        tle = get_tle_by_resno(dpns->outer_tlist, varattno);
        if (!tle)
            elog(ERROR, "bogus varattno for OUTER_VAR var: %d", varattno);
 
        Assert(netlevelsup == 0);
        push_child_plan(dpns, dpns->outer_plan, &save_dpns);
 
        result = get_name_for_var_field((Var *) tle->expr, fieldno,
                                        levelsup, context);
 
        pop_child_plan(dpns, &save_dpns);
        return result;
    }
    else if (varno == INNER_VAR && dpns->inner_tlist)
    {
        TargetEntry *tle;
        deparse_namespace save_dpns;
        const char *result;
 
        tle = get_tle_by_resno(dpns->inner_tlist, varattno);
        if (!tle)
            elog(ERROR, "bogus varattno for INNER_VAR var: %d", varattno);
 
        Assert(netlevelsup == 0);
        push_child_plan(dpns, dpns->inner_plan, &save_dpns);
 
        result = get_name_for_var_field((Var *) tle->expr, fieldno,
                                        levelsup, context);
 
        pop_child_plan(dpns, &save_dpns);
        return result;
    }
    else if (varno == INDEX_VAR && dpns->index_tlist)
    {
        TargetEntry *tle;
        const char *result;
 
        tle = get_tle_by_resno(dpns->index_tlist, varattno);
        if (!tle)
            elog(ERROR, "bogus varattno for INDEX_VAR var: %d", varattno);
 
        Assert(netlevelsup == 0);
 
        result = get_name_for_var_field((Var *) tle->expr, fieldno,
                                        levelsup, context);
 
        return result;
    }
    else
    {
        elog(ERROR, "bogus varno: %d", varno);
        return NULL;            /* keep compiler quiet */
    }
 
    if (attnum == InvalidAttrNumber)
    {
        /* Var is whole-row reference to RTE, so select the right field */
        return get_rte_attribute_name(rte, fieldno);
    }
 
    /*
     * This part has essentially the same logic as the parser's
     * expandRecordVariable() function, but we are dealing with a different
     * representation of the input context, and we only need one field name
     * not a TupleDesc.  Also, we need special cases for finding subquery and
     * CTE subplans when deparsing Plan trees.
     */
    expr = (Node *) var;        /* default if we can't drill down */
 
    switch (rte->rtekind)
    {
        case RTE_RELATION:
        case RTE_VALUES:
        case RTE_NAMEDTUPLESTORE:
        case RTE_RESULT:
 
            /*
             * This case should not occur: a column of a table, values list,
             * or ENR shouldn't have type RECORD.  Fall through and fail (most
             * likely) at the bottom.
             */
            break;
        case RTE_SUBQUERY:
            /* Subselect-in-FROM: examine sub-select's output expr */
            {
                if (rte->subquery)
                {
                    TargetEntry *ste = get_tle_by_resno(rte->subquery->targetList,
                                                        attnum);
 
                    if (ste == NULL || ste->resjunk)
                        elog(ERROR, "subquery %s does not have attribute %d",
                             rte->eref->aliasname, attnum);
                    expr = (Node *) ste->expr;
                    if (IsA(expr, Var))
                    {
                        /*
                         * Recurse into the sub-select to see what its Var
                         * refers to. We have to build an additional level of
                         * namespace to keep in step with varlevelsup in the
                         * subselect; furthermore, the subquery RTE might be
                         * from an outer query level, in which case the
                         * namespace for the subselect must have that outer
                         * level as parent namespace.
                         */
                        List       *save_nslist = context->namespaces;
                        List       *parent_namespaces;
                        deparse_namespace mydpns;
                        const char *result;
 
                        parent_namespaces = list_copy_tail(context->namespaces,
                                                           netlevelsup);
 
                        set_deparse_for_query(&mydpns, rte->subquery,
                                              parent_namespaces);
 
                        context->namespaces = lcons(&mydpns, parent_namespaces);
 
                        result = get_name_for_var_field((Var *) expr, fieldno,
                                                        0, context);
 
                        context->namespaces = save_nslist;
 
                        return result;
                    }
                    /* else fall through to inspect the expression */
                }
                else
                {
                    /*
                     * We're deparsing a Plan tree so we don't have complete
                     * RTE entries (in particular, rte->subquery is NULL). But
                     * the only place we'd normally see a Var directly
                     * referencing a SUBQUERY RTE is in a SubqueryScan plan
                     * node, and we can look into the child plan's tlist
                     * instead.  An exception occurs if the subquery was
                     * proven empty and optimized away: then we'd find such a
                     * Var in a childless Result node, and there's nothing in
                     * the plan tree that would let us figure out what it had
                     * originally referenced.  In that case, fall back on
                     * printing "fN", analogously to the default column names
                     * for RowExprs.
                     */
                    TargetEntry *tle;
                    deparse_namespace save_dpns;
                    const char *result;
 
                    if (!dpns->inner_plan)
                    {
                        char       *dummy_name = palloc(32);
 
                        Assert(dpns->plan && IsA(dpns->plan, Result));
                        snprintf(dummy_name, 32, "f%d", fieldno);
                        return dummy_name;
                    }
                    Assert(dpns->plan && IsA(dpns->plan, SubqueryScan));
 
                    tle = get_tle_by_resno(dpns->inner_tlist, attnum);
                    if (!tle)
                        elog(ERROR, "bogus varattno for subquery var: %d",
                             attnum);
                    Assert(netlevelsup == 0);
                    push_child_plan(dpns, dpns->inner_plan, &save_dpns);
 
                    result = get_name_for_var_field((Var *) tle->expr, fieldno,
                                                    levelsup, context);
 
                    pop_child_plan(dpns, &save_dpns);
                    return result;
                }
            }
            break;
        case RTE_JOIN:
            /* Join RTE --- recursively inspect the alias variable */
            if (rte->joinaliasvars == NIL)
                elog(ERROR, "cannot decompile join alias var in plan tree");
            Assert(attnum > 0 && attnum <= list_length(rte->joinaliasvars));
            expr = (Node *) list_nth(rte->joinaliasvars, attnum - 1);
            Assert(expr != NULL);
            /* we intentionally don't strip implicit coercions here */
            if (IsA(expr, Var))
                return get_name_for_var_field((Var *) expr, fieldno,
                                              var->varlevelsup + levelsup,
                                              context);
            /* else fall through to inspect the expression */
            break;
        case RTE_FUNCTION:
        case RTE_TABLEFUNC:
 
            /*
             * We couldn't get here unless a function is declared with one of
             * its result columns as RECORD, which is not allowed.
             */
            break;
        case RTE_CTE:
            /* CTE reference: examine subquery's output expr */
            {
                CommonTableExpr *cte = NULL;
                Index       ctelevelsup;
                ListCell   *lc;
 
                /*
                 * Try to find the referenced CTE using the namespace stack.
                 */
                ctelevelsup = rte->ctelevelsup + netlevelsup;
                if (ctelevelsup >= list_length(context->namespaces))
                    lc = NULL;
                else
                {
                    deparse_namespace *ctedpns;
 
                    ctedpns = (deparse_namespace *)
                        list_nth(context->namespaces, ctelevelsup);
                    foreach(lc, ctedpns->ctes)
                    {
                        cte = (CommonTableExpr *) lfirst(lc);
                        if (strcmp(cte->ctename, rte->ctename) == 0)
                            break;
                    }
                }
                if (lc != NULL)
                {
                    Query      *ctequery = (Query *) cte->ctequery;
                    TargetEntry *ste = get_tle_by_resno(GetCTETargetList(cte),
                                                        attnum);
 
                    if (ste == NULL || ste->resjunk)
                        elog(ERROR, "CTE %s does not have attribute %d",
                             rte->eref->aliasname, attnum);
                    expr = (Node *) ste->expr;
                    if (IsA(expr, Var))
                    {
                        /*
                         * Recurse into the CTE to see what its Var refers to.
                         * We have to build an additional level of namespace
                         * to keep in step with varlevelsup in the CTE;
                         * furthermore it could be an outer CTE (compare
                         * SUBQUERY case above).
                         */
                        List       *save_nslist = context->namespaces;
                        List       *parent_namespaces;
                        deparse_namespace mydpns;
                        const char *result;
 
                        parent_namespaces = list_copy_tail(context->namespaces,
                                                           ctelevelsup);
 
                        set_deparse_for_query(&mydpns, ctequery,
                                              parent_namespaces);
 
                        context->namespaces = lcons(&mydpns, parent_namespaces);
 
                        result = get_name_for_var_field((Var *) expr, fieldno,
                                                        0, context);
 
                        context->namespaces = save_nslist;
 
                        return result;
                    }
                    /* else fall through to inspect the expression */
                }
                else
                {
                    /*
                     * We're deparsing a Plan tree so we don't have a CTE
                     * list.  But the only places we'd normally see a Var
                     * directly referencing a CTE RTE are in CteScan or
                     * WorkTableScan plan nodes.  For those cases,
                     * set_deparse_plan arranged for dpns->inner_plan to be
                     * the plan node that emits the CTE or RecursiveUnion
                     * result, and we can look at its tlist instead.  As
                     * above, this can fail if the CTE has been proven empty,
                     * in which case fall back to "fN".
                     */
                    TargetEntry *tle;
                    deparse_namespace save_dpns;
                    const char *result;
 
                    if (!dpns->inner_plan)
                    {
                        char       *dummy_name = palloc(32);
 
                        Assert(dpns->plan && IsA(dpns->plan, Result));
                        snprintf(dummy_name, 32, "f%d", fieldno);
                        return dummy_name;
                    }
                    Assert(dpns->plan && (IsA(dpns->plan, CteScan) ||
                                          IsA(dpns->plan, WorkTableScan)));
 
                    tle = get_tle_by_resno(dpns->inner_tlist, attnum);
                    if (!tle)
                        elog(ERROR, "bogus varattno for subquery var: %d",
                             attnum);
                    Assert(netlevelsup == 0);
                    push_child_plan(dpns, dpns->inner_plan, &save_dpns);
 
                    result = get_name_for_var_field((Var *) tle->expr, fieldno,
                                                    levelsup, context);
 
                    pop_child_plan(dpns, &save_dpns);
                    return result;
                }
            }
            break;
        case RTE_GROUP:
 
            /*
             * We couldn't get here: any Vars that reference the RTE_GROUP RTE
             * should have been replaced with the underlying grouping
             * expressions.
             */
            break;
    }
 
    /*
     * We now have an expression we can't expand any more, so see if
     * get_expr_result_tupdesc() can do anything with it.
     */
    tupleDesc = get_expr_result_tupdesc(expr, false);
    /* Got the tupdesc, so we can extract the field name */
    Assert(fieldno >= 1 && fieldno <= tupleDesc->natts);
    return NameStr(TupleDescAttr(tupleDesc, fieldno - 1)->attname);
}
 
/*
 * Try to find the referenced expression for a PARAM_EXEC Param that might
 * reference a parameter supplied by an upper NestLoop or SubPlan plan node.
 *
 * If successful, return the expression and set *dpns_p and *ancestor_cell_p
 * appropriately for calling push_ancestor_plan().  If no referent can be
 * found, return NULL.
 */
static Node *
find_param_referent(Param *param, deparse_context *context,
                    deparse_namespace **dpns_p, ListCell **ancestor_cell_p)
{
    /* Initialize output parameters to prevent compiler warnings */
    *dpns_p = NULL;
    *ancestor_cell_p = NULL;
 
    /*
     * If it's a PARAM_EXEC parameter, look for a matching NestLoopParam or
     * SubPlan argument.  This will necessarily be in some ancestor of the
     * current expression's Plan node.
     */
    if (param->paramkind == PARAM_EXEC)
    {
        deparse_namespace *dpns;
        Plan       *child_plan;
        ListCell   *lc;
 
        dpns = (deparse_namespace *) linitial(context->namespaces);
        child_plan = dpns->plan;
 
        foreach(lc, dpns->ancestors)
        {
            Node       *ancestor = (Node *) lfirst(lc);
            ListCell   *lc2;
 
            /*
             * NestLoops transmit params to their inner child only.
             */
            if (IsA(ancestor, NestLoop) &&
                child_plan == innerPlan(ancestor))
            {
                NestLoop   *nl = (NestLoop *) ancestor;
 
                foreach(lc2, nl->nestParams)
                {
                    NestLoopParam *nlp = (NestLoopParam *) lfirst(lc2);
 
                    if (nlp->paramno == param->paramid)
                    {
                        /* Found a match, so return it */
                        *dpns_p = dpns;
                        *ancestor_cell_p = lc;
                        return (Node *) nlp->paramval;
                    }
                }
            }
 
            /*
             * If ancestor is a SubPlan, check the arguments it provides.
             */
            if (IsA(ancestor, SubPlan))
            {
                SubPlan    *subplan = (SubPlan *) ancestor;
                ListCell   *lc3;
                ListCell   *lc4;
 
                forboth(lc3, subplan->parParam, lc4, subplan->args)
                {
                    int         paramid = lfirst_int(lc3);
                    Node       *arg = (Node *) lfirst(lc4);
 
                    if (paramid == param->paramid)
                    {
                        /*
                         * Found a match, so return it.  But, since Vars in
                         * the arg are to be evaluated in the surrounding
                         * context, we have to point to the next ancestor item
                         * that is *not* a SubPlan.
                         */
                        ListCell   *rest;
 
                        for_each_cell(rest, dpns->ancestors,
                                      lnext(dpns->ancestors, lc))
                        {
                            Node       *ancestor2 = (Node *) lfirst(rest);
 
                            if (!IsA(ancestor2, SubPlan))
                            {
                                *dpns_p = dpns;
                                *ancestor_cell_p = rest;
                                return arg;
                            }
                        }
                        elog(ERROR, "SubPlan cannot be outermost ancestor");
                    }
                }
 
                /* SubPlan isn't a kind of Plan, so skip the rest */
                continue;
            }
 
            /*
             * We need not consider the ancestor's initPlan list, since
             * initplans never have any parParams.
             */
 
            /* No luck, crawl up to next ancestor */
            child_plan = (Plan *) ancestor;
        }
    }
 
    /* No referent found */
    return NULL;
}
 
/*
 * Try to find a subplan/initplan that emits the value for a PARAM_EXEC Param.
 *
 * If successful, return the generating subplan/initplan and set *column_p
 * to the subplan's 0-based output column number.
 * Otherwise, return NULL.
 */
static SubPlan *
find_param_generator(Param *param, deparse_context *context, int *column_p)
{
    /* Initialize output parameter to prevent compiler warnings */
    *column_p = 0;
 
    /*
     * If it's a PARAM_EXEC parameter, search the current plan node as well as
     * ancestor nodes looking for a subplan or initplan that emits the value
     * for the Param.  It could appear in the setParams of an initplan or
     * MULTIEXPR_SUBLINK subplan, or in the paramIds of an ancestral SubPlan.
     */
    if (param->paramkind == PARAM_EXEC)
    {
        SubPlan    *result;
        deparse_namespace *dpns;
        ListCell   *lc;
 
        dpns = (deparse_namespace *) linitial(context->namespaces);
 
        /* First check the innermost plan node's initplans */
        result = find_param_generator_initplan(param, dpns->plan, column_p);
        if (result)
            return result;
 
        /*
         * The plan's targetlist might contain MULTIEXPR_SUBLINK SubPlans,
         * which can be referenced by Params elsewhere in the targetlist.
         * (Such Params should always be in the same targetlist, so there's no
         * need to do this work at upper plan nodes.)
         */
        foreach_node(TargetEntry, tle, dpns->plan->targetlist)
        {
            if (tle->expr && IsA(tle->expr, SubPlan))
            {
                SubPlan    *subplan = (SubPlan *) tle->expr;
 
                if (subplan->subLinkType == MULTIEXPR_SUBLINK)
                {
                    foreach_int(paramid, subplan->setParam)
                    {
                        if (paramid == param->paramid)
                        {
                            /* Found a match, so return it. */
                            *column_p = foreach_current_index(paramid);
                            return subplan;
                        }
                    }
                }
            }
        }
 
        /* No luck, so check the ancestor nodes */
        foreach(lc, dpns->ancestors)
        {
            Node       *ancestor = (Node *) lfirst(lc);
 
            /*
             * If ancestor is a SubPlan, check the paramIds it provides.
             */
            if (IsA(ancestor, SubPlan))
            {
                SubPlan    *subplan = (SubPlan *) ancestor;
 
                foreach_int(paramid, subplan->paramIds)
                {
                    if (paramid == param->paramid)
                    {
                        /* Found a match, so return it. */
                        *column_p = foreach_current_index(paramid);
                        return subplan;
                    }
                }
 
                /* SubPlan isn't a kind of Plan, so skip the rest */
                continue;
            }
 
            /*
             * Otherwise, it's some kind of Plan node, so check its initplans.
             */
            result = find_param_generator_initplan(param, (Plan *) ancestor,
                                                   column_p);
            if (result)
                return result;
 
            /* No luck, crawl up to next ancestor */
        }
    }
 
    /* No generator found */
    return NULL;
}
 
/*
 * Subroutine for find_param_generator: search one Plan node's initplans
 */
static SubPlan *
find_param_generator_initplan(Param *param, Plan *plan, int *column_p)
{
    foreach_node(SubPlan, subplan, plan->initPlan)
    {
        foreach_int(paramid, subplan->setParam)
        {
            if (paramid == param->paramid)
            {
                /* Found a match, so return it. */
                *column_p = foreach_current_index(paramid);
                return subplan;
            }
        }
    }
    return NULL;
}
 
/*
 * Display a Param appropriately.
 */
static void
get_parameter(Param *param, deparse_context *context)
{
    Node       *expr;
    deparse_namespace *dpns;
    ListCell   *ancestor_cell;
    SubPlan    *subplan;
    int         column;
 
    /*
     * If it's a PARAM_EXEC parameter, try to locate the expression from which
     * the parameter was computed.  This stanza handles only cases in which
     * the Param represents an input to the subplan we are currently in.
     */
    expr = find_param_referent(param, context, &dpns, &ancestor_cell);
    if (expr)
    {
        /* Found a match, so print it */
        deparse_namespace save_dpns;
        bool        save_varprefix;
        bool        need_paren;
 
        /* Switch attention to the ancestor plan node */
        push_ancestor_plan(dpns, ancestor_cell, &save_dpns);
 
        /*
         * Force prefixing of Vars, since they won't belong to the relation
         * being scanned in the original plan node.
         */
        save_varprefix = context->varprefix;
        context->varprefix = true;
 
        /*
         * A Param's expansion is typically a Var, Aggref, GroupingFunc, or
         * upper-level Param, which wouldn't need extra parentheses.
         * Otherwise, insert parens to ensure the expression looks atomic.
         */
        need_paren = !(IsA(expr, Var) ||
                       IsA(expr, Aggref) ||
                       IsA(expr, GroupingFunc) ||
                       IsA(expr, Param));
        if (need_paren)
            appendStringInfoChar(context->buf, '(');
 
        get_rule_expr(expr, context, false);
 
        if (need_paren)
            appendStringInfoChar(context->buf, ')');
 
        context->varprefix = save_varprefix;
 
        pop_ancestor_plan(dpns, &save_dpns);
 
        return;
    }
 
    /*
     * Alternatively, maybe it's a subplan output, which we print as a
     * reference to the subplan.  (We could drill down into the subplan and
     * print the relevant targetlist expression, but that has been deemed too
     * confusing since it would violate normal SQL scope rules.  Also, we're
     * relying on this reference to show that the testexpr containing the
     * Param has anything to do with that subplan at all.)
     */
    subplan = find_param_generator(param, context, &column);
    if (subplan)
    {
        appendStringInfo(context->buf, "(%s%s).col%d",
                         subplan->useHashTable ? "hashed " : "",
                         subplan->plan_name, column + 1);
 
        return;
    }
 
    /*
     * If it's an external parameter, see if the outermost namespace provides
     * function argument names.
     */
    if (param->paramkind == PARAM_EXTERN && context->namespaces != NIL)
    {
        dpns = llast(context->namespaces);
        if (dpns->argnames &&
            param->paramid > 0 &&
            param->paramid <= dpns->numargs)
        {
            char       *argname = dpns->argnames[param->paramid - 1];
 
            if (argname)
            {
                bool        should_qualify = false;
                ListCell   *lc;
 
                /*
                 * Qualify the parameter name if there are any other deparse
                 * namespaces with range tables.  This avoids qualifying in
                 * trivial cases like "RETURN a + b", but makes it safe in all
                 * other cases.
                 */
                foreach(lc, context->namespaces)
                {
                    deparse_namespace *depns = lfirst(lc);
 
                    if (depns->rtable_names != NIL)
                    {
                        should_qualify = true;
                        break;
                    }
                }
                if (should_qualify)
                {
                    appendStringInfoString(context->buf, quote_identifier(dpns->funcname));
                    appendStringInfoChar(context->buf, '.');
                }
 
                appendStringInfoString(context->buf, quote_identifier(argname));
                return;
            }
        }
    }
 
    /*
     * Not PARAM_EXEC, or couldn't find referent: just print $N.
     *
     * It's a bug if we get here for anything except PARAM_EXTERN Params, but
     * in production builds printing $N seems more useful than failing.
     */
    Assert(param->paramkind == PARAM_EXTERN);
 
    appendStringInfo(context->buf, "$%d", param->paramid);
}
 
/*
 * get_simple_binary_op_name
 *
 * helper function for isSimpleNode
 * will return single char binary operator name, or NULL if it's not
 */
static const char *
get_simple_binary_op_name(OpExpr *expr)
{
    List       *args = expr->args;
 
    if (list_length(args) == 2)
    {
        /* binary operator */
        Node       *arg1 = (Node *) linitial(args);
        Node       *arg2 = (Node *) lsecond(args);
        const char *op;
 
        op = generate_operator_name(expr->opno, exprType(arg1), exprType(arg2));
        if (strlen(op) == 1)
            return op;
    }
    return NULL;
}
 
 
/*
 * isSimpleNode - check if given node is simple (doesn't need parenthesizing)
 *
 *  true   : simple in the context of parent node's type
 *  false  : not simple
 */
static bool
isSimpleNode(Node *node, Node *parentNode, int prettyFlags)
{
    if (!node)
        return false;
 
    switch (nodeTag(node))
    {
        case T_Var:
        case T_Const:
        case T_Param:
        case T_CoerceToDomainValue:
        case T_SetToDefault:
        case T_CurrentOfExpr:
            /* single words: always simple */
            return true;
 
        case T_SubscriptingRef:
        case T_ArrayExpr:
        case T_RowExpr:
        case T_CoalesceExpr:
        case T_MinMaxExpr:
        case T_SQLValueFunction:
        case T_XmlExpr:
        case T_NextValueExpr:
        case T_NullIfExpr:
        case T_Aggref:
        case T_GroupingFunc:
        case T_WindowFunc:
        case T_MergeSupportFunc:
        case T_FuncExpr:
        case T_JsonConstructorExpr:
        case T_JsonExpr:
            /* function-like: name(..) or name[..] */
            return true;
 
            /* CASE keywords act as parentheses */
        case T_CaseExpr:
            return true;
 
        case T_FieldSelect:
 
            /*
             * appears simple since . has top precedence, unless parent is
             * T_FieldSelect itself!
             */
            return !IsA(parentNode, FieldSelect);
 
        case T_FieldStore:
 
            /*
             * treat like FieldSelect (probably doesn't matter)
             */
            return !IsA(parentNode, FieldStore);
 
        case T_CoerceToDomain:
            /* maybe simple, check args */
            return isSimpleNode((Node *) ((CoerceToDomain *) node)->arg,
                                node, prettyFlags);
        case T_RelabelType:
            return isSimpleNode((Node *) ((RelabelType *) node)->arg,
                                node, prettyFlags);
        case T_CoerceViaIO:
            return isSimpleNode((Node *) ((CoerceViaIO *) node)->arg,
                                node, prettyFlags);
        case T_ArrayCoerceExpr:
            return isSimpleNode((Node *) ((ArrayCoerceExpr *) node)->arg,
                                node, prettyFlags);
        case T_ConvertRowtypeExpr:
            return isSimpleNode((Node *) ((ConvertRowtypeExpr *) node)->arg,
                                node, prettyFlags);
        case T_ReturningExpr:
            return isSimpleNode((Node *) ((ReturningExpr *) node)->retexpr,
                                node, prettyFlags);
 
        case T_OpExpr:
            {
                /* depends on parent node type; needs further checking */
                if (prettyFlags & PRETTYFLAG_PAREN && IsA(parentNode, OpExpr))
                {
                    const char *op;
                    const char *parentOp;
                    bool        is_lopriop;
                    bool        is_hipriop;
                    bool        is_lopriparent;
                    bool        is_hipriparent;
 
                    op = get_simple_binary_op_name((OpExpr *) node);
                    if (!op)
                        return false;
 
                    /* We know only the basic operators + - and * / % */
                    is_lopriop = (strchr("+-", *op) != NULL);
                    is_hipriop = (strchr("*/%", *op) != NULL);
                    if (!(is_lopriop || is_hipriop))
                        return false;
 
                    parentOp = get_simple_binary_op_name((OpExpr *) parentNode);
                    if (!parentOp)
                        return false;
 
                    is_lopriparent = (strchr("+-", *parentOp) != NULL);
                    is_hipriparent = (strchr("*/%", *parentOp) != NULL);
                    if (!(is_lopriparent || is_hipriparent))
                        return false;
 
                    if (is_hipriop && is_lopriparent)
                        return true;    /* op binds tighter than parent */
 
                    if (is_lopriop && is_hipriparent)
                        return false;
 
                    /*
                     * Operators are same priority --- can skip parens only if
                     * we have (a - b) - c, not a - (b - c).
                     */
                    if (node == (Node *) linitial(((OpExpr *) parentNode)->args))
                        return true;
 
                    return false;
                }
                /* else do the same stuff as for T_SubLink et al. */
            }
            /* FALLTHROUGH */
 
        case T_SubLink:
        case T_NullTest:
        case T_BooleanTest:
        case T_DistinctExpr:
        case T_JsonIsPredicate:
            switch (nodeTag(parentNode))
            {
                case T_FuncExpr:
                    {
                        /* special handling for casts and COERCE_SQL_SYNTAX */
                        CoercionForm type = ((FuncExpr *) parentNode)->funcformat;
 
                        if (type == COERCE_EXPLICIT_CAST ||
                            type == COERCE_IMPLICIT_CAST ||
                            type == COERCE_SQL_SYNTAX)
                            return false;
                        return true;    /* own parentheses */
                    }
                case T_BoolExpr:    /* lower precedence */
                case T_SubscriptingRef: /* other separators */
                case T_ArrayExpr:   /* other separators */
                case T_RowExpr: /* other separators */
                case T_CoalesceExpr:    /* own parentheses */
                case T_MinMaxExpr:  /* own parentheses */
                case T_XmlExpr: /* own parentheses */
                case T_NullIfExpr:  /* other separators */
                case T_Aggref:  /* own parentheses */
                case T_GroupingFunc:    /* own parentheses */
                case T_WindowFunc:  /* own parentheses */
                case T_CaseExpr:    /* other separators */
                    return true;
                default:
                    return false;
            }
 
        case T_BoolExpr:
            switch (nodeTag(parentNode))
            {
                case T_BoolExpr:
                    if (prettyFlags & PRETTYFLAG_PAREN)
                    {
                        BoolExprType type;
                        BoolExprType parentType;
 
                        type = ((BoolExpr *) node)->boolop;
                        parentType = ((BoolExpr *) parentNode)->boolop;
                        switch (type)
                        {
                            case NOT_EXPR:
                            case AND_EXPR:
                                if (parentType == AND_EXPR || parentType == OR_EXPR)
                                    return true;
                                break;
                            case OR_EXPR:
                                if (parentType == OR_EXPR)
                                    return true;
                                break;
                        }
                    }
                    return false;
                case T_FuncExpr:
                    {
                        /* special handling for casts and COERCE_SQL_SYNTAX */
                        CoercionForm type = ((FuncExpr *) parentNode)->funcformat;
 
                        if (type == COERCE_EXPLICIT_CAST ||
                            type == COERCE_IMPLICIT_CAST ||
                            type == COERCE_SQL_SYNTAX)
                            return false;
                        return true;    /* own parentheses */
                    }
                case T_SubscriptingRef: /* other separators */
                case T_ArrayExpr:   /* other separators */
                case T_RowExpr: /* other separators */
                case T_CoalesceExpr:    /* own parentheses */
                case T_MinMaxExpr:  /* own parentheses */
                case T_XmlExpr: /* own parentheses */
                case T_NullIfExpr:  /* other separators */
                case T_Aggref:  /* own parentheses */
                case T_GroupingFunc:    /* own parentheses */
                case T_WindowFunc:  /* own parentheses */
                case T_CaseExpr:    /* other separators */
                case T_JsonExpr:    /* own parentheses */
                    return true;
                default:
                    return false;
            }
 
        case T_JsonValueExpr:
            /* maybe simple, check args */
            return isSimpleNode((Node *) ((JsonValueExpr *) node)->raw_expr,
                                node, prettyFlags);
 
        default:
            break;
    }
    /* those we don't know: in dubio complexo */
    return false;
}
 
 
/*
 * appendContextKeyword - append a keyword to buffer
 *
 * If prettyPrint is enabled, perform a line break, and adjust indentation.
 * Otherwise, just append the keyword.
 */
static void
appendContextKeyword(deparse_context *context, const char *str,
                     int indentBefore, int indentAfter, int indentPlus)
{
    StringInfo  buf = context->buf;
 
    if (PRETTY_INDENT(context))
    {
        int         indentAmount;
 
        context->indentLevel += indentBefore;
 
        /* remove any trailing spaces currently in the buffer ... */
        removeStringInfoSpaces(buf);
        /* ... then add a newline and some spaces */
        appendStringInfoChar(buf, '\n');
 
        if (context->indentLevel < PRETTYINDENT_LIMIT)
            indentAmount = Max(context->indentLevel, 0) + indentPlus;
        else
        {
            /*
             * If we're indented more than PRETTYINDENT_LIMIT characters, try
             * to conserve horizontal space by reducing the per-level
             * indentation.  For best results the scale factor here should
             * divide all the indent amounts that get added to indentLevel
             * (PRETTYINDENT_STD, etc).  It's important that the indentation
             * not grow unboundedly, else deeply-nested trees use O(N^2)
             * whitespace; so we also wrap modulo PRETTYINDENT_LIMIT.
             */
            indentAmount = PRETTYINDENT_LIMIT +
                (context->indentLevel - PRETTYINDENT_LIMIT) /
                (PRETTYINDENT_STD / 2);
            indentAmount %= PRETTYINDENT_LIMIT;
            /* scale/wrap logic affects indentLevel, but not indentPlus */
            indentAmount += indentPlus;
        }
        appendStringInfoSpaces(buf, indentAmount);
 
        appendStringInfoString(buf, str);
 
        context->indentLevel += indentAfter;
        if (context->indentLevel < 0)
            context->indentLevel = 0;
    }
    else
        appendStringInfoString(buf, str);
}
 
/*
 * removeStringInfoSpaces - delete trailing spaces from a buffer.
 *
 * Possibly this should move to stringinfo.c at some point.
 */
static void
removeStringInfoSpaces(StringInfo str)
{
    while (str->len > 0 && str->data[str->len - 1] == ' ')
        str->data[--(str->len)] = '\0';
}
 
 
/*
 * get_rule_expr_paren  - deparse expr using get_rule_expr,
 * embracing the string with parentheses if necessary for prettyPrint.
 *
 * Never embrace if prettyFlags=0, because it's done in the calling node.
 *
 * Any node that does *not* embrace its argument node by sql syntax (with
 * parentheses, non-operator keywords like CASE/WHEN/ON, or comma etc) should
 * use get_rule_expr_paren instead of get_rule_expr so parentheses can be
 * added.
 */
static void
get_rule_expr_paren(Node *node, deparse_context *context,
                    bool showimplicit, Node *parentNode)
{
    bool        need_paren;
 
    need_paren = PRETTY_PAREN(context) &&
        !isSimpleNode(node, parentNode, context->prettyFlags);
 
    if (need_paren)
        appendStringInfoChar(context->buf, '(');
 
    get_rule_expr(node, context, showimplicit);
 
    if (need_paren)
        appendStringInfoChar(context->buf, ')');
}
 
static void
get_json_behavior(JsonBehavior *behavior, deparse_context *context,
                  const char *on)
{
    /*
     * The order of array elements must correspond to the order of
     * JsonBehaviorType members.
     */
    const char *behavior_names[] =
    {
        " NULL",
        " ERROR",
        " EMPTY",
        " TRUE",
        " FALSE",
        " UNKNOWN",
        " EMPTY ARRAY",
        " EMPTY OBJECT",
        " DEFAULT "
    };
 
    if ((int) behavior->btype < 0 || behavior->btype >= lengthof(behavior_names))
        elog(ERROR, "invalid json behavior type: %d", behavior->btype);
 
    appendStringInfoString(context->buf, behavior_names[behavior->btype]);
 
    if (behavior->btype == JSON_BEHAVIOR_DEFAULT)
        get_rule_expr(behavior->expr, context, false);
 
    appendStringInfo(context->buf, " ON %s", on);
}
 
/*
 * get_json_expr_options
 *
 * Parse back common options for JSON_QUERY, JSON_VALUE, JSON_EXISTS and
 * JSON_TABLE columns.
 */
static void
get_json_expr_options(JsonExpr *jsexpr, deparse_context *context,
                      JsonBehaviorType default_behavior)
{
    if (jsexpr->op == JSON_QUERY_OP)
    {
        if (jsexpr->wrapper == JSW_CONDITIONAL)
            appendStringInfoString(context->buf, " WITH CONDITIONAL WRAPPER");
        else if (jsexpr->wrapper == JSW_UNCONDITIONAL)
            appendStringInfoString(context->buf, " WITH UNCONDITIONAL WRAPPER");
        /* The default */
        else if (jsexpr->wrapper == JSW_NONE || jsexpr->wrapper == JSW_UNSPEC)
            appendStringInfoString(context->buf, " WITHOUT WRAPPER");
 
        if (jsexpr->omit_quotes)
            appendStringInfoString(context->buf, " OMIT QUOTES");
        /* The default */
        else
            appendStringInfoString(context->buf, " KEEP QUOTES");
    }
 
    if (jsexpr->on_empty && jsexpr->on_empty->btype != default_behavior)
        get_json_behavior(jsexpr->on_empty, context, "EMPTY");
 
    if (jsexpr->on_error && jsexpr->on_error->btype != default_behavior)
        get_json_behavior(jsexpr->on_error, context, "ERROR");
}
 
/* ----------
 * get_rule_expr            - Parse back an expression
 *
 * Note: showimplicit determines whether we display any implicit cast that
 * is present at the top of the expression tree.  It is a passed argument,
 * not a field of the context struct, because we change the value as we
 * recurse down into the expression.  In general we suppress implicit casts
 * when the result type is known with certainty (eg, the arguments of an
 * OR must be boolean).  We display implicit casts for arguments of functions
 * and operators, since this is needed to be certain that the same function
 * or operator will be chosen when the expression is re-parsed.
 * ----------
 */
static void
get_rule_expr(Node *node, deparse_context *context,
              bool showimplicit)
{
    StringInfo  buf = context->buf;
 
    if (node == NULL)
        return;
 
    /* Guard against excessively long or deeply-nested queries */
    CHECK_FOR_INTERRUPTS();
    check_stack_depth();
 
    /*
     * Each level of get_rule_expr must emit an indivisible term
     * (parenthesized if necessary) to ensure result is reparsed into the same
     * expression tree.  The only exception is that when the input is a List,
     * we emit the component items comma-separated with no surrounding
     * decoration; this is convenient for most callers.
     */
    switch (nodeTag(node))
    {
        case T_Var:
            (void) get_variable((Var *) node, 0, false, context);
            break;
 
        case T_Const:
            get_const_expr((Const *) node, context, 0);
            break;
 
        case T_Param:
            get_parameter((Param *) node, context);
            break;
 
        case T_Aggref:
            get_agg_expr((Aggref *) node, context, (Aggref *) node);
            break;
 
        case T_GroupingFunc:
            {
                GroupingFunc *gexpr = (GroupingFunc *) node;
 
                appendStringInfoString(buf, "GROUPING(");
                get_rule_expr((Node *) gexpr->args, context, true);
                appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_WindowFunc:
            get_windowfunc_expr((WindowFunc *) node, context);
            break;
 
        case T_MergeSupportFunc:
            appendStringInfoString(buf, "MERGE_ACTION()");
            break;
 
        case T_SubscriptingRef:
            {
                SubscriptingRef *sbsref = (SubscriptingRef *) node;
                bool        need_parens;
 
                /*
                 * If the argument is a CaseTestExpr, we must be inside a
                 * FieldStore, ie, we are assigning to an element of an array
                 * within a composite column.  Since we already punted on
                 * displaying the FieldStore's target information, just punt
                 * here too, and display only the assignment source
                 * expression.
                 */
                if (IsA(sbsref->refexpr, CaseTestExpr))
                {
                    Assert(sbsref->refassgnexpr);
                    get_rule_expr((Node *) sbsref->refassgnexpr,
                                  context, showimplicit);
                    break;
                }
 
                /*
                 * Parenthesize the argument unless it's a simple Var or a
                 * FieldSelect.  (In particular, if it's another
                 * SubscriptingRef, we *must* parenthesize to avoid
                 * confusion.)
                 */
                need_parens = !IsA(sbsref->refexpr, Var) &&
                    !IsA(sbsref->refexpr, FieldSelect);
                if (need_parens)
                    appendStringInfoChar(buf, '(');
                get_rule_expr((Node *) sbsref->refexpr, context, showimplicit);
                if (need_parens)
                    appendStringInfoChar(buf, ')');
 
                /*
                 * If there's a refassgnexpr, we want to print the node in the
                 * format "container[subscripts] := refassgnexpr".  This is
                 * not legal SQL, so decompilation of INSERT or UPDATE
                 * statements should always use processIndirection as part of
                 * the statement-level syntax.  We should only see this when
                 * EXPLAIN tries to print the targetlist of a plan resulting
                 * from such a statement.
                 */
                if (sbsref->refassgnexpr)
                {
                    Node       *refassgnexpr;
 
                    /*
                     * Use processIndirection to print this node's subscripts
                     * as well as any additional field selections or
                     * subscripting in immediate descendants.  It returns the
                     * RHS expr that is actually being "assigned".
                     */
                    refassgnexpr = processIndirection(node, context);
                    appendStringInfoString(buf, " := ");
                    get_rule_expr(refassgnexpr, context, showimplicit);
                }
                else
                {
                    /* Just an ordinary container fetch, so print subscripts */
                    printSubscripts(sbsref, context);
                }
            }
            break;
 
        case T_FuncExpr:
            get_func_expr((FuncExpr *) node, context, showimplicit);
            break;
 
        case T_NamedArgExpr:
            {
                NamedArgExpr *na = (NamedArgExpr *) node;
 
                appendStringInfo(buf, "%s => ", quote_identifier(na->name));
                get_rule_expr((Node *) na->arg, context, showimplicit);
            }
            break;
 
        case T_OpExpr:
            get_oper_expr((OpExpr *) node, context);
            break;
 
        case T_DistinctExpr:
            {
                DistinctExpr *expr = (DistinctExpr *) node;
                List       *args = expr->args;
                Node       *arg1 = (Node *) linitial(args);
                Node       *arg2 = (Node *) lsecond(args);
 
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, '(');
                get_rule_expr_paren(arg1, context, true, node);
                appendStringInfoString(buf, " IS DISTINCT FROM ");
                get_rule_expr_paren(arg2, context, true, node);
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_NullIfExpr:
            {
                NullIfExpr *nullifexpr = (NullIfExpr *) node;
 
                appendStringInfoString(buf, "NULLIF(");
                get_rule_expr((Node *) nullifexpr->args, context, true);
                appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_ScalarArrayOpExpr:
            {
                ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
                List       *args = expr->args;
                Node       *arg1 = (Node *) linitial(args);
                Node       *arg2 = (Node *) lsecond(args);
 
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, '(');
                get_rule_expr_paren(arg1, context, true, node);
                appendStringInfo(buf, " %s %s (",
                                 generate_operator_name(expr->opno,
                                                        exprType(arg1),
                                                        get_base_element_type(exprType(arg2))),
                                 expr->useOr ? "ANY" : "ALL");
                get_rule_expr_paren(arg2, context, true, node);
 
                /*
                 * There's inherent ambiguity in "x op ANY/ALL (y)" when y is
                 * a bare sub-SELECT.  Since we're here, the sub-SELECT must
                 * be meant as a scalar sub-SELECT yielding an array value to
                 * be used in ScalarArrayOpExpr; but the grammar will
                 * preferentially interpret such a construct as an ANY/ALL
                 * SubLink.  To prevent misparsing the output that way, insert
                 * a dummy coercion (which will be stripped by parse analysis,
                 * so no inefficiency is added in dump and reload).  This is
                 * indeed most likely what the user wrote to get the construct
                 * accepted in the first place.
                 */
                if (IsA(arg2, SubLink) &&
                    ((SubLink *) arg2)->subLinkType == EXPR_SUBLINK)
                    appendStringInfo(buf, "::%s",
                                     format_type_with_typemod(exprType(arg2),
                                                              exprTypmod(arg2)));
                appendStringInfoChar(buf, ')');
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_BoolExpr:
            {
                BoolExpr   *expr = (BoolExpr *) node;
                Node       *first_arg = linitial(expr->args);
                ListCell   *arg;
 
                switch (expr->boolop)
                {
                    case AND_EXPR:
                        if (!PRETTY_PAREN(context))
                            appendStringInfoChar(buf, '(');
                        get_rule_expr_paren(first_arg, context,
                                            false, node);
                        for_each_from(arg, expr->args, 1)
                        {
                            appendStringInfoString(buf, " AND ");
                            get_rule_expr_paren((Node *) lfirst(arg), context,
                                                false, node);
                        }
                        if (!PRETTY_PAREN(context))
                            appendStringInfoChar(buf, ')');
                        break;
 
                    case OR_EXPR:
                        if (!PRETTY_PAREN(context))
                            appendStringInfoChar(buf, '(');
                        get_rule_expr_paren(first_arg, context,
                                            false, node);
                        for_each_from(arg, expr->args, 1)
                        {
                            appendStringInfoString(buf, " OR ");
                            get_rule_expr_paren((Node *) lfirst(arg), context,
                                                false, node);
                        }
                        if (!PRETTY_PAREN(context))
                            appendStringInfoChar(buf, ')');
                        break;
 
                    case NOT_EXPR:
                        if (!PRETTY_PAREN(context))
                            appendStringInfoChar(buf, '(');
                        appendStringInfoString(buf, "NOT ");
                        get_rule_expr_paren(first_arg, context,
                                            false, node);
                        if (!PRETTY_PAREN(context))
                            appendStringInfoChar(buf, ')');
                        break;
 
                    default:
                        elog(ERROR, "unrecognized boolop: %d",
                             (int) expr->boolop);
                }
            }
            break;
 
        case T_SubLink:
            get_sublink_expr((SubLink *) node, context);
            break;
 
        case T_SubPlan:
            {
                SubPlan    *subplan = (SubPlan *) node;
 
                /*
                 * We cannot see an already-planned subplan in rule deparsing,
                 * only while EXPLAINing a query plan.  We don't try to
                 * reconstruct the original SQL, just reference the subplan
                 * that appears elsewhere in EXPLAIN's result.  It does seem
                 * useful to show the subLinkType and testexpr (if any), and
                 * we also note whether the subplan will be hashed.
                 */
                switch (subplan->subLinkType)
                {
                    case EXISTS_SUBLINK:
                        appendStringInfoString(buf, "EXISTS(");
                        Assert(subplan->testexpr == NULL);
                        break;
                    case ALL_SUBLINK:
                        appendStringInfoString(buf, "(ALL ");
                        Assert(subplan->testexpr != NULL);
                        break;
                    case ANY_SUBLINK:
                        appendStringInfoString(buf, "(ANY ");
                        Assert(subplan->testexpr != NULL);
                        break;
                    case ROWCOMPARE_SUBLINK:
                        /* Parenthesizing the testexpr seems sufficient */
                        appendStringInfoChar(buf, '(');
                        Assert(subplan->testexpr != NULL);
                        break;
                    case EXPR_SUBLINK:
                        /* No need to decorate these subplan references */
                        appendStringInfoChar(buf, '(');
                        Assert(subplan->testexpr == NULL);
                        break;
                    case MULTIEXPR_SUBLINK:
                        /* MULTIEXPR isn't executed in the normal way */
                        appendStringInfoString(buf, "(rescan ");
                        Assert(subplan->testexpr == NULL);
                        break;
                    case ARRAY_SUBLINK:
                        appendStringInfoString(buf, "ARRAY(");
                        Assert(subplan->testexpr == NULL);
                        break;
                    case CTE_SUBLINK:
                        /* This case is unreachable within expressions */
                        appendStringInfoString(buf, "CTE(");
                        Assert(subplan->testexpr == NULL);
                        break;
                }
 
                if (subplan->testexpr != NULL)
                {
                    deparse_namespace *dpns;
 
                    /*
                     * Push SubPlan into ancestors list while deparsing
                     * testexpr, so that we can handle PARAM_EXEC references
                     * to the SubPlan's paramIds.  (This makes it look like
                     * the SubPlan is an "ancestor" of the current plan node,
                     * which is a little weird, but it does no harm.)  In this
                     * path, we don't need to mention the SubPlan explicitly,
                     * because the referencing Params will show its existence.
                     */
                    dpns = (deparse_namespace *) linitial(context->namespaces);
                    dpns->ancestors = lcons(subplan, dpns->ancestors);
 
                    get_rule_expr(subplan->testexpr, context, showimplicit);
                    appendStringInfoChar(buf, ')');
 
                    dpns->ancestors = list_delete_first(dpns->ancestors);
                }
                else
                {
                    /* No referencing Params, so show the SubPlan's name */
                    if (subplan->useHashTable)
                        appendStringInfo(buf, "hashed %s)", subplan->plan_name);
                    else
                        appendStringInfo(buf, "%s)", subplan->plan_name);
                }
            }
            break;
 
        case T_AlternativeSubPlan:
            {
                AlternativeSubPlan *asplan = (AlternativeSubPlan *) node;
                ListCell   *lc;
 
                /*
                 * This case cannot be reached in normal usage, since no
                 * AlternativeSubPlan can appear either in parsetrees or
                 * finished plan trees.  We keep it just in case somebody
                 * wants to use this code to print planner data structures.
                 */
                appendStringInfoString(buf, "(alternatives: ");
                foreach(lc, asplan->subplans)
                {
                    SubPlan    *splan = lfirst_node(SubPlan, lc);
 
                    if (splan->useHashTable)
                        appendStringInfo(buf, "hashed %s", splan->plan_name);
                    else
                        appendStringInfoString(buf, splan->plan_name);
                    if (lnext(asplan->subplans, lc))
                        appendStringInfoString(buf, " or ");
                }
                appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_FieldSelect:
            {
                FieldSelect *fselect = (FieldSelect *) node;
                Node       *arg = (Node *) fselect->arg;
                int         fno = fselect->fieldnum;
                const char *fieldname;
                bool        need_parens;
 
                /*
                 * Parenthesize the argument unless it's an SubscriptingRef or
                 * another FieldSelect.  Note in particular that it would be
                 * WRONG to not parenthesize a Var argument; simplicity is not
                 * the issue here, having the right number of names is.
                 */
                need_parens = !IsA(arg, SubscriptingRef) &&
                    !IsA(arg, FieldSelect);
                if (need_parens)
                    appendStringInfoChar(buf, '(');
                get_rule_expr(arg, context, true);
                if (need_parens)
                    appendStringInfoChar(buf, ')');
 
                /*
                 * Get and print the field name.
                 */
                fieldname = get_name_for_var_field((Var *) arg, fno,
                                                   0, context);
                appendStringInfo(buf, ".%s", quote_identifier(fieldname));
            }
            break;
 
        case T_FieldStore:
            {
                FieldStore *fstore = (FieldStore *) node;
                bool        need_parens;
 
                /*
                 * There is no good way to represent a FieldStore as real SQL,
                 * so decompilation of INSERT or UPDATE statements should
                 * always use processIndirection as part of the
                 * statement-level syntax.  We should only get here when
                 * EXPLAIN tries to print the targetlist of a plan resulting
                 * from such a statement.  The plan case is even harder than
                 * ordinary rules would be, because the planner tries to
                 * collapse multiple assignments to the same field or subfield
                 * into one FieldStore; so we can see a list of target fields
                 * not just one, and the arguments could be FieldStores
                 * themselves.  We don't bother to try to print the target
                 * field names; we just print the source arguments, with a
                 * ROW() around them if there's more than one.  This isn't
                 * terribly complete, but it's probably good enough for
                 * EXPLAIN's purposes; especially since anything more would be
                 * either hopelessly confusing or an even poorer
                 * representation of what the plan is actually doing.
                 */
                need_parens = (list_length(fstore->newvals) != 1);
                if (need_parens)
                    appendStringInfoString(buf, "ROW(");
                get_rule_expr((Node *) fstore->newvals, context, showimplicit);
                if (need_parens)
                    appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_RelabelType:
            {
                RelabelType *relabel = (RelabelType *) node;
                Node       *arg = (Node *) relabel->arg;
 
                if (relabel->relabelformat == COERCE_IMPLICIT_CAST &&
                    !showimplicit)
                {
                    /* don't show the implicit cast */
                    get_rule_expr_paren(arg, context, false, node);
                }
                else
                {
                    get_coercion_expr(arg, context,
                                      relabel->resulttype,
                                      relabel->resulttypmod,
                                      node);
                }
            }
            break;
 
        case T_CoerceViaIO:
            {
                CoerceViaIO *iocoerce = (CoerceViaIO *) node;
                Node       *arg = (Node *) iocoerce->arg;
 
                if (iocoerce->coerceformat == COERCE_IMPLICIT_CAST &&
                    !showimplicit)
                {
                    /* don't show the implicit cast */
                    get_rule_expr_paren(arg, context, false, node);
                }
                else
                {
                    get_coercion_expr(arg, context,
                                      iocoerce->resulttype,
                                      -1,
                                      node);
                }
            }
            break;
 
        case T_ArrayCoerceExpr:
            {
                ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) node;
                Node       *arg = (Node *) acoerce->arg;
 
                if (acoerce->coerceformat == COERCE_IMPLICIT_CAST &&
                    !showimplicit)
                {
                    /* don't show the implicit cast */
                    get_rule_expr_paren(arg, context, false, node);
                }
                else
                {
                    get_coercion_expr(arg, context,
                                      acoerce->resulttype,
                                      acoerce->resulttypmod,
                                      node);
                }
            }
            break;
 
        case T_ConvertRowtypeExpr:
            {
                ConvertRowtypeExpr *convert = (ConvertRowtypeExpr *) node;
                Node       *arg = (Node *) convert->arg;
 
                if (convert->convertformat == COERCE_IMPLICIT_CAST &&
                    !showimplicit)
                {
                    /* don't show the implicit cast */
                    get_rule_expr_paren(arg, context, false, node);
                }
                else
                {
                    get_coercion_expr(arg, context,
                                      convert->resulttype, -1,
                                      node);
                }
            }
            break;
 
        case T_CollateExpr:
            {
                CollateExpr *collate = (CollateExpr *) node;
                Node       *arg = (Node *) collate->arg;
 
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, '(');
                get_rule_expr_paren(arg, context, showimplicit, node);
                appendStringInfo(buf, " COLLATE %s",
                                 generate_collation_name(collate->collOid));
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_CaseExpr:
            {
                CaseExpr   *caseexpr = (CaseExpr *) node;
                ListCell   *temp;
 
                appendContextKeyword(context, "CASE",
                                     0, PRETTYINDENT_VAR, 0);
                if (caseexpr->arg)
                {
                    appendStringInfoChar(buf, ' ');
                    get_rule_expr((Node *) caseexpr->arg, context, true);
                }
                foreach(temp, caseexpr->args)
                {
                    CaseWhen   *when = (CaseWhen *) lfirst(temp);
                    Node       *w = (Node *) when->expr;
 
                    if (caseexpr->arg)
                    {
                        /*
                         * The parser should have produced WHEN clauses of the
                         * form "CaseTestExpr = RHS", possibly with an
                         * implicit coercion inserted above the CaseTestExpr.
                         * For accurate decompilation of rules it's essential
                         * that we show just the RHS.  However in an
                         * expression that's been through the optimizer, the
                         * WHEN clause could be almost anything (since the
                         * equality operator could have been expanded into an
                         * inline function).  If we don't recognize the form
                         * of the WHEN clause, just punt and display it as-is.
                         */
                        if (IsA(w, OpExpr))
                        {
                            List       *args = ((OpExpr *) w)->args;
 
                            if (list_length(args) == 2 &&
                                IsA(strip_implicit_coercions(linitial(args)),
                                    CaseTestExpr))
                                w = (Node *) lsecond(args);
                        }
                    }
 
                    if (!PRETTY_INDENT(context))
                        appendStringInfoChar(buf, ' ');
                    appendContextKeyword(context, "WHEN ",
                                         0, 0, 0);
                    get_rule_expr(w, context, false);
                    appendStringInfoString(buf, " THEN ");
                    get_rule_expr((Node *) when->result, context, true);
                }
                if (!PRETTY_INDENT(context))
                    appendStringInfoChar(buf, ' ');
                appendContextKeyword(context, "ELSE ",
                                     0, 0, 0);
                get_rule_expr((Node *) caseexpr->defresult, context, true);
                if (!PRETTY_INDENT(context))
                    appendStringInfoChar(buf, ' ');
                appendContextKeyword(context, "END",
                                     -PRETTYINDENT_VAR, 0, 0);
            }
            break;
 
        case T_CaseTestExpr:
            {
                /*
                 * Normally we should never get here, since for expressions
                 * that can contain this node type we attempt to avoid
                 * recursing to it.  But in an optimized expression we might
                 * be unable to avoid that (see comments for CaseExpr).  If we
                 * do see one, print it as CASE_TEST_EXPR.
                 */
                appendStringInfoString(buf, "CASE_TEST_EXPR");
            }
            break;
 
        case T_ArrayExpr:
            {
                ArrayExpr  *arrayexpr = (ArrayExpr *) node;
 
                appendStringInfoString(buf, "ARRAY[");
                get_rule_expr((Node *) arrayexpr->elements, context, true);
                appendStringInfoChar(buf, ']');
 
                /*
                 * If the array isn't empty, we assume its elements are
                 * coerced to the desired type.  If it's empty, though, we
                 * need an explicit coercion to the array type.
                 */
                if (arrayexpr->elements == NIL)
                    appendStringInfo(buf, "::%s",
                                     format_type_with_typemod(arrayexpr->array_typeid, -1));
            }
            break;
 
        case T_RowExpr:
            {
                RowExpr    *rowexpr = (RowExpr *) node;
                TupleDesc   tupdesc = NULL;
                ListCell   *arg;
                int         i;
                char       *sep;
 
                /*
                 * If it's a named type and not RECORD, we may have to skip
                 * dropped columns and/or claim there are NULLs for added
                 * columns.
                 */
                if (rowexpr->row_typeid != RECORDOID)
                {
                    tupdesc = lookup_rowtype_tupdesc(rowexpr->row_typeid, -1);
                    Assert(list_length(rowexpr->args) <= tupdesc->natts);
                }
 
                /*
                 * SQL99 allows "ROW" to be omitted when there is more than
                 * one column, but for simplicity we always print it.
                 */
                appendStringInfoString(buf, "ROW(");
                sep = "";
                i = 0;
                foreach(arg, rowexpr->args)
                {
                    Node       *e = (Node *) lfirst(arg);
 
                    if (tupdesc == NULL ||
                        !TupleDescAttr(tupdesc, i)->attisdropped)
                    {
                        appendStringInfoString(buf, sep);
                        /* Whole-row Vars need special treatment here */
                        get_rule_expr_toplevel(e, context, true);
                        sep = ", ";
                    }
                    i++;
                }
                if (tupdesc != NULL)
                {
                    while (i < tupdesc->natts)
                    {
                        if (!TupleDescAttr(tupdesc, i)->attisdropped)
                        {
                            appendStringInfoString(buf, sep);
                            appendStringInfoString(buf, "NULL");
                            sep = ", ";
                        }
                        i++;
                    }
 
                    ReleaseTupleDesc(tupdesc);
                }
                appendStringInfoChar(buf, ')');
                if (rowexpr->row_format == COERCE_EXPLICIT_CAST)
                    appendStringInfo(buf, "::%s",
                                     format_type_with_typemod(rowexpr->row_typeid, -1));
            }
            break;
 
        case T_RowCompareExpr:
            {
                RowCompareExpr *rcexpr = (RowCompareExpr *) node;
 
                /*
                 * SQL99 allows "ROW" to be omitted when there is more than
                 * one column, but for simplicity we always print it.  Within
                 * a ROW expression, whole-row Vars need special treatment, so
                 * use get_rule_list_toplevel.
                 */
                appendStringInfoString(buf, "(ROW(");
                get_rule_list_toplevel(rcexpr->largs, context, true);
 
                /*
                 * We assume that the name of the first-column operator will
                 * do for all the rest too.  This is definitely open to
                 * failure, eg if some but not all operators were renamed
                 * since the construct was parsed, but there seems no way to
                 * be perfect.
                 */
                appendStringInfo(buf, ") %s ROW(",
                                 generate_operator_name(linitial_oid(rcexpr->opnos),
                                                        exprType(linitial(rcexpr->largs)),
                                                        exprType(linitial(rcexpr->rargs))));
                get_rule_list_toplevel(rcexpr->rargs, context, true);
                appendStringInfoString(buf, "))");
            }
            break;
 
        case T_CoalesceExpr:
            {
                CoalesceExpr *coalesceexpr = (CoalesceExpr *) node;
 
                appendStringInfoString(buf, "COALESCE(");
                get_rule_expr((Node *) coalesceexpr->args, context, true);
                appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_MinMaxExpr:
            {
                MinMaxExpr *minmaxexpr = (MinMaxExpr *) node;
 
                switch (minmaxexpr->op)
                {
                    case IS_GREATEST:
                        appendStringInfoString(buf, "GREATEST(");
                        break;
                    case IS_LEAST:
                        appendStringInfoString(buf, "LEAST(");
                        break;
                }
                get_rule_expr((Node *) minmaxexpr->args, context, true);
                appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_SQLValueFunction:
            {
                SQLValueFunction *svf = (SQLValueFunction *) node;
 
                /*
                 * Note: this code knows that typmod for time, timestamp, and
                 * timestamptz just prints as integer.
                 */
                switch (svf->op)
                {
                    case SVFOP_CURRENT_DATE:
                        appendStringInfoString(buf, "CURRENT_DATE");
                        break;
                    case SVFOP_CURRENT_TIME:
                        appendStringInfoString(buf, "CURRENT_TIME");
                        break;
                    case SVFOP_CURRENT_TIME_N:
                        appendStringInfo(buf, "CURRENT_TIME(%d)", svf->typmod);
                        break;
                    case SVFOP_CURRENT_TIMESTAMP:
                        appendStringInfoString(buf, "CURRENT_TIMESTAMP");
                        break;
                    case SVFOP_CURRENT_TIMESTAMP_N:
                        appendStringInfo(buf, "CURRENT_TIMESTAMP(%d)",
                                         svf->typmod);
                        break;
                    case SVFOP_LOCALTIME:
                        appendStringInfoString(buf, "LOCALTIME");
                        break;
                    case SVFOP_LOCALTIME_N:
                        appendStringInfo(buf, "LOCALTIME(%d)", svf->typmod);
                        break;
                    case SVFOP_LOCALTIMESTAMP:
                        appendStringInfoString(buf, "LOCALTIMESTAMP");
                        break;
                    case SVFOP_LOCALTIMESTAMP_N:
                        appendStringInfo(buf, "LOCALTIMESTAMP(%d)",
                                         svf->typmod);
                        break;
                    case SVFOP_CURRENT_ROLE:
                        appendStringInfoString(buf, "CURRENT_ROLE");
                        break;
                    case SVFOP_CURRENT_USER:
                        appendStringInfoString(buf, "CURRENT_USER");
                        break;
                    case SVFOP_USER:
                        appendStringInfoString(buf, "USER");
                        break;
                    case SVFOP_SESSION_USER:
                        appendStringInfoString(buf, "SESSION_USER");
                        break;
                    case SVFOP_CURRENT_CATALOG:
                        appendStringInfoString(buf, "CURRENT_CATALOG");
                        break;
                    case SVFOP_CURRENT_SCHEMA:
                        appendStringInfoString(buf, "CURRENT_SCHEMA");
                        break;
                }
            }
            break;
 
        case T_XmlExpr:
            {
                XmlExpr    *xexpr = (XmlExpr *) node;
                bool        needcomma = false;
                ListCell   *arg;
                ListCell   *narg;
                Const      *con;
 
                switch (xexpr->op)
                {
                    case IS_XMLCONCAT:
                        appendStringInfoString(buf, "XMLCONCAT(");
                        break;
                    case IS_XMLELEMENT:
                        appendStringInfoString(buf, "XMLELEMENT(");
                        break;
                    case IS_XMLFOREST:
                        appendStringInfoString(buf, "XMLFOREST(");
                        break;
                    case IS_XMLPARSE:
                        appendStringInfoString(buf, "XMLPARSE(");
                        break;
                    case IS_XMLPI:
                        appendStringInfoString(buf, "XMLPI(");
                        break;
                    case IS_XMLROOT:
                        appendStringInfoString(buf, "XMLROOT(");
                        break;
                    case IS_XMLSERIALIZE:
                        appendStringInfoString(buf, "XMLSERIALIZE(");
                        break;
                    case IS_DOCUMENT:
                        break;
                }
                if (xexpr->op == IS_XMLPARSE || xexpr->op == IS_XMLSERIALIZE)
                {
                    if (xexpr->xmloption == XMLOPTION_DOCUMENT)
                        appendStringInfoString(buf, "DOCUMENT ");
                    else
                        appendStringInfoString(buf, "CONTENT ");
                }
                if (xexpr->name)
                {
                    appendStringInfo(buf, "NAME %s",
                                     quote_identifier(map_xml_name_to_sql_identifier(xexpr->name)));
                    needcomma = true;
                }
                if (xexpr->named_args)
                {
                    if (xexpr->op != IS_XMLFOREST)
                    {
                        if (needcomma)
                            appendStringInfoString(buf, ", ");
                        appendStringInfoString(buf, "XMLATTRIBUTES(");
                        needcomma = false;
                    }
                    forboth(arg, xexpr->named_args, narg, xexpr->arg_names)
                    {
                        Node       *e = (Node *) lfirst(arg);
                        char       *argname = strVal(lfirst(narg));
 
                        if (needcomma)
                            appendStringInfoString(buf, ", ");
                        get_rule_expr((Node *) e, context, true);
                        appendStringInfo(buf, " AS %s",
                                         quote_identifier(map_xml_name_to_sql_identifier(argname)));
                        needcomma = true;
                    }
                    if (xexpr->op != IS_XMLFOREST)
                        appendStringInfoChar(buf, ')');
                }
                if (xexpr->args)
                {
                    if (needcomma)
                        appendStringInfoString(buf, ", ");
                    switch (xexpr->op)
                    {
                        case IS_XMLCONCAT:
                        case IS_XMLELEMENT:
                        case IS_XMLFOREST:
                        case IS_XMLPI:
                        case IS_XMLSERIALIZE:
                            /* no extra decoration needed */
                            get_rule_expr((Node *) xexpr->args, context, true);
                            break;
                        case IS_XMLPARSE:
                            Assert(list_length(xexpr->args) == 2);
 
                            get_rule_expr((Node *) linitial(xexpr->args),
                                          context, true);
 
                            con = lsecond_node(Const, xexpr->args);
                            Assert(!con->constisnull);
                            if (DatumGetBool(con->constvalue))
                                appendStringInfoString(buf,
                                                       " PRESERVE WHITESPACE");
                            else
                                appendStringInfoString(buf,
                                                       " STRIP WHITESPACE");
                            break;
                        case IS_XMLROOT:
                            Assert(list_length(xexpr->args) == 3);
 
                            get_rule_expr((Node *) linitial(xexpr->args),
                                          context, true);
 
                            appendStringInfoString(buf, ", VERSION ");
                            con = (Const *) lsecond(xexpr->args);
                            if (IsA(con, Const) &&
                                con->constisnull)
                                appendStringInfoString(buf, "NO VALUE");
                            else
                                get_rule_expr((Node *) con, context, false);
 
                            con = lthird_node(Const, xexpr->args);
                            if (con->constisnull)
                                 /* suppress STANDALONE NO VALUE */ ;
                            else
                            {
                                switch (DatumGetInt32(con->constvalue))
                                {
                                    case XML_STANDALONE_YES:
                                        appendStringInfoString(buf,
                                                               ", STANDALONE YES");
                                        break;
                                    case XML_STANDALONE_NO:
                                        appendStringInfoString(buf,
                                                               ", STANDALONE NO");
                                        break;
                                    case XML_STANDALONE_NO_VALUE:
                                        appendStringInfoString(buf,
                                                               ", STANDALONE NO VALUE");
                                        break;
                                    default:
                                        break;
                                }
                            }
                            break;
                        case IS_DOCUMENT:
                            get_rule_expr_paren((Node *) xexpr->args, context, false, node);
                            break;
                    }
                }
                if (xexpr->op == IS_XMLSERIALIZE)
                {
                    appendStringInfo(buf, " AS %s",
                                     format_type_with_typemod(xexpr->type,
                                                              xexpr->typmod));
                    if (xexpr->indent)
                        appendStringInfoString(buf, " INDENT");
                    else
                        appendStringInfoString(buf, " NO INDENT");
                }
 
                if (xexpr->op == IS_DOCUMENT)
                    appendStringInfoString(buf, " IS DOCUMENT");
                else
                    appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_NullTest:
            {
                NullTest   *ntest = (NullTest *) node;
 
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, '(');
                get_rule_expr_paren((Node *) ntest->arg, context, true, node);
 
                /*
                 * For scalar inputs, we prefer to print as IS [NOT] NULL,
                 * which is shorter and traditional.  If it's a rowtype input
                 * but we're applying a scalar test, must print IS [NOT]
                 * DISTINCT FROM NULL to be semantically correct.
                 */
                if (ntest->argisrow ||
                    !type_is_rowtype(exprType((Node *) ntest->arg)))
                {
                    switch (ntest->nulltesttype)
                    {
                        case IS_NULL:
                            appendStringInfoString(buf, " IS NULL");
                            break;
                        case IS_NOT_NULL:
                            appendStringInfoString(buf, " IS NOT NULL");
                            break;
                        default:
                            elog(ERROR, "unrecognized nulltesttype: %d",
                                 (int) ntest->nulltesttype);
                    }
                }
                else
                {
                    switch (ntest->nulltesttype)
                    {
                        case IS_NULL:
                            appendStringInfoString(buf, " IS NOT DISTINCT FROM NULL");
                            break;
                        case IS_NOT_NULL:
                            appendStringInfoString(buf, " IS DISTINCT FROM NULL");
                            break;
                        default:
                            elog(ERROR, "unrecognized nulltesttype: %d",
                                 (int) ntest->nulltesttype);
                    }
                }
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_BooleanTest:
            {
                BooleanTest *btest = (BooleanTest *) node;
 
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, '(');
                get_rule_expr_paren((Node *) btest->arg, context, false, node);
                switch (btest->booltesttype)
                {
                    case IS_TRUE:
                        appendStringInfoString(buf, " IS TRUE");
                        break;
                    case IS_NOT_TRUE:
                        appendStringInfoString(buf, " IS NOT TRUE");
                        break;
                    case IS_FALSE:
                        appendStringInfoString(buf, " IS FALSE");
                        break;
                    case IS_NOT_FALSE:
                        appendStringInfoString(buf, " IS NOT FALSE");
                        break;
                    case IS_UNKNOWN:
                        appendStringInfoString(buf, " IS UNKNOWN");
                        break;
                    case IS_NOT_UNKNOWN:
                        appendStringInfoString(buf, " IS NOT UNKNOWN");
                        break;
                    default:
                        elog(ERROR, "unrecognized booltesttype: %d",
                             (int) btest->booltesttype);
                }
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_CoerceToDomain:
            {
                CoerceToDomain *ctest = (CoerceToDomain *) node;
                Node       *arg = (Node *) ctest->arg;
 
                if (ctest->coercionformat == COERCE_IMPLICIT_CAST &&
                    !showimplicit)
                {
                    /* don't show the implicit cast */
                    get_rule_expr(arg, context, false);
                }
                else
                {
                    get_coercion_expr(arg, context,
                                      ctest->resulttype,
                                      ctest->resulttypmod,
                                      node);
                }
            }
            break;
 
        case T_CoerceToDomainValue:
            appendStringInfoString(buf, "VALUE");
            break;
 
        case T_SetToDefault:
            appendStringInfoString(buf, "DEFAULT");
            break;
 
        case T_CurrentOfExpr:
            {
                CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
 
                if (cexpr->cursor_name)
                    appendStringInfo(buf, "CURRENT OF %s",
                                     quote_identifier(cexpr->cursor_name));
                else
                    appendStringInfo(buf, "CURRENT OF $%d",
                                     cexpr->cursor_param);
            }
            break;
 
        case T_NextValueExpr:
            {
                NextValueExpr *nvexpr = (NextValueExpr *) node;
 
                /*
                 * This isn't exactly nextval(), but that seems close enough
                 * for EXPLAIN's purposes.
                 */
                appendStringInfoString(buf, "nextval(");
                simple_quote_literal(buf,
                                     generate_relation_name(nvexpr->seqid,
                                                            NIL));
                appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_InferenceElem:
            {
                InferenceElem *iexpr = (InferenceElem *) node;
                bool        save_varprefix;
                bool        need_parens;
 
                /*
                 * InferenceElem can only refer to target relation, so a
                 * prefix is not useful, and indeed would cause parse errors.
                 */
                save_varprefix = context->varprefix;
                context->varprefix = false;
 
                /*
                 * Parenthesize the element unless it's a simple Var or a bare
                 * function call.  Follows pg_get_indexdef_worker().
                 */
                need_parens = !IsA(iexpr->expr, Var);
                if (IsA(iexpr->expr, FuncExpr) &&
                    ((FuncExpr *) iexpr->expr)->funcformat ==
                    COERCE_EXPLICIT_CALL)
                    need_parens = false;
 
                if (need_parens)
                    appendStringInfoChar(buf, '(');
                get_rule_expr((Node *) iexpr->expr,
                              context, false);
                if (need_parens)
                    appendStringInfoChar(buf, ')');
 
                context->varprefix = save_varprefix;
 
                if (iexpr->infercollid)
                    appendStringInfo(buf, " COLLATE %s",
                                     generate_collation_name(iexpr->infercollid));
 
                /* Add the operator class name, if not default */
                if (iexpr->inferopclass)
                {
                    Oid         inferopclass = iexpr->inferopclass;
                    Oid         inferopcinputtype = get_opclass_input_type(iexpr->inferopclass);
 
                    get_opclass_name(inferopclass, inferopcinputtype, buf);
                }
            }
            break;
 
        case T_ReturningExpr:
            {
                ReturningExpr *retExpr = (ReturningExpr *) node;
 
                /*
                 * We cannot see a ReturningExpr in rule deparsing, only while
                 * EXPLAINing a query plan (ReturningExpr nodes are only ever
                 * adding during query rewriting). Just display the expression
                 * returned (an expanded view column).
                 */
                get_rule_expr((Node *) retExpr->retexpr, context, showimplicit);
            }
            break;
 
        case T_PartitionBoundSpec:
            {
                PartitionBoundSpec *spec = (PartitionBoundSpec *) node;
                ListCell   *cell;
                char       *sep;
 
                if (spec->is_default)
                {
                    appendStringInfoString(buf, "DEFAULT");
                    break;
                }
 
                switch (spec->strategy)
                {
                    case PARTITION_STRATEGY_HASH:
                        Assert(spec->modulus > 0 && spec->remainder >= 0);
                        Assert(spec->modulus > spec->remainder);
 
                        appendStringInfoString(buf, "FOR VALUES");
                        appendStringInfo(buf, " WITH (modulus %d, remainder %d)",
                                         spec->modulus, spec->remainder);
                        break;
 
                    case PARTITION_STRATEGY_LIST:
                        Assert(spec->listdatums != NIL);
 
                        appendStringInfoString(buf, "FOR VALUES IN (");
                        sep = "";
                        foreach(cell, spec->listdatums)
                        {
                            Const      *val = lfirst_node(Const, cell);
 
                            appendStringInfoString(buf, sep);
                            get_const_expr(val, context, -1);
                            sep = ", ";
                        }
 
                        appendStringInfoChar(buf, ')');
                        break;
 
                    case PARTITION_STRATEGY_RANGE:
                        Assert(spec->lowerdatums != NIL &&
                               spec->upperdatums != NIL &&
                               list_length(spec->lowerdatums) ==
                               list_length(spec->upperdatums));
 
                        appendStringInfo(buf, "FOR VALUES FROM %s TO %s",
                                         get_range_partbound_string(spec->lowerdatums),
                                         get_range_partbound_string(spec->upperdatums));
                        break;
 
                    default:
                        elog(ERROR, "unrecognized partition strategy: %d",
                             (int) spec->strategy);
                        break;
                }
            }
            break;
 
        case T_JsonValueExpr:
            {
                JsonValueExpr *jve = (JsonValueExpr *) node;
 
                get_rule_expr((Node *) jve->raw_expr, context, false);
                get_json_format(jve->format, context->buf);
            }
            break;
 
        case T_JsonConstructorExpr:
            get_json_constructor((JsonConstructorExpr *) node, context, false);
            break;
 
        case T_JsonIsPredicate:
            {
                JsonIsPredicate *pred = (JsonIsPredicate *) node;
 
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(context->buf, '(');
 
                get_rule_expr_paren(pred->expr, context, true, node);
 
                appendStringInfoString(context->buf, " IS JSON");
 
                /* TODO: handle FORMAT clause */
 
                switch (pred->item_type)
                {
                    case JS_TYPE_SCALAR:
                        appendStringInfoString(context->buf, " SCALAR");
                        break;
                    case JS_TYPE_ARRAY:
                        appendStringInfoString(context->buf, " ARRAY");
                        break;
                    case JS_TYPE_OBJECT:
                        appendStringInfoString(context->buf, " OBJECT");
                        break;
                    default:
                        break;
                }
 
                if (pred->unique_keys)
                    appendStringInfoString(context->buf, " WITH UNIQUE KEYS");
 
                if (!PRETTY_PAREN(context))
                    appendStringInfoChar(context->buf, ')');
            }
            break;
 
        case T_JsonExpr:
            {
                JsonExpr   *jexpr = (JsonExpr *) node;
 
                switch (jexpr->op)
                {
                    case JSON_EXISTS_OP:
                        appendStringInfoString(buf, "JSON_EXISTS(");
                        break;
                    case JSON_QUERY_OP:
                        appendStringInfoString(buf, "JSON_QUERY(");
                        break;
                    case JSON_VALUE_OP:
                        appendStringInfoString(buf, "JSON_VALUE(");
                        break;
                    default:
                        elog(ERROR, "unrecognized JsonExpr op: %d",
                             (int) jexpr->op);
                }
 
                get_rule_expr(jexpr->formatted_expr, context, showimplicit);
 
                appendStringInfoString(buf, ", ");
 
                get_json_path_spec(jexpr->path_spec, context, showimplicit);
 
                if (jexpr->passing_values)
                {
                    ListCell   *lc1,
                               *lc2;
                    bool        needcomma = false;
 
                    appendStringInfoString(buf, " PASSING ");
 
                    forboth(lc1, jexpr->passing_names,
                            lc2, jexpr->passing_values)
                    {
                        if (needcomma)
                            appendStringInfoString(buf, ", ");
                        needcomma = true;
 
                        get_rule_expr((Node *) lfirst(lc2), context, showimplicit);
                        appendStringInfo(buf, " AS %s",
                                         quote_identifier(lfirst_node(String, lc1)->sval));
                    }
                }
 
                if (jexpr->op != JSON_EXISTS_OP ||
                    jexpr->returning->typid != BOOLOID)
                    get_json_returning(jexpr->returning, context->buf,
                                       jexpr->op == JSON_QUERY_OP);
 
                get_json_expr_options(jexpr, context,
                                      jexpr->op != JSON_EXISTS_OP ?
                                      JSON_BEHAVIOR_NULL :
                                      JSON_BEHAVIOR_FALSE);
 
                appendStringInfoChar(buf, ')');
            }
            break;
 
        case T_List:
            {
                char       *sep;
                ListCell   *l;
 
                sep = "";
                foreach(l, (List *) node)
                {
                    appendStringInfoString(buf, sep);
                    get_rule_expr((Node *) lfirst(l), context, showimplicit);
                    sep = ", ";
                }
            }
            break;
 
        case T_TableFunc:
            get_tablefunc((TableFunc *) node, context, showimplicit);
            break;
 
        default:
            elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
            break;
    }
}
 
/*
 * get_rule_expr_toplevel       - Parse back a toplevel expression
 *
 * Same as get_rule_expr(), except that if the expr is just a Var, we pass
 * istoplevel = true not false to get_variable().  This causes whole-row Vars
 * to get printed with decoration that will prevent expansion of "*".
 * We need to use this in contexts such as ROW() and VALUES(), where the
 * parser would expand "foo.*" appearing at top level.  (In principle we'd
 * use this in get_target_list() too, but that has additional worries about
 * whether to print AS, so it needs to invoke get_variable() directly anyway.)
 */
static void
get_rule_expr_toplevel(Node *node, deparse_context *context,
                       bool showimplicit)
{
    if (node && IsA(node, Var))
        (void) get_variable((Var *) node, 0, true, context);
    else
        get_rule_expr(node, context, showimplicit);
}
 
/*
 * get_rule_list_toplevel       - Parse back a list of toplevel expressions
 *
 * Apply get_rule_expr_toplevel() to each element of a List.
 *
 * This adds commas between the expressions, but caller is responsible
 * for printing surrounding decoration.
 */
static void
get_rule_list_toplevel(List *lst, deparse_context *context,
                       bool showimplicit)
{
    const char *sep;
    ListCell   *lc;
 
    sep = "";
    foreach(lc, lst)
    {
        Node       *e = (Node *) lfirst(lc);
 
        appendStringInfoString(context->buf, sep);
        get_rule_expr_toplevel(e, context, showimplicit);
        sep = ", ";
    }
}
 
/*
 * get_rule_expr_funccall       - Parse back a function-call expression
 *
 * Same as get_rule_expr(), except that we guarantee that the output will
 * look like a function call, or like one of the things the grammar treats as
 * equivalent to a function call (see the func_expr_windowless production).
 * This is needed in places where the grammar uses func_expr_windowless and
 * you can't substitute a parenthesized a_expr.  If what we have isn't going
 * to look like a function call, wrap it in a dummy CAST() expression, which
 * will satisfy the grammar --- and, indeed, is likely what the user wrote to
 * produce such a thing.
 */
static void
get_rule_expr_funccall(Node *node, deparse_context *context,
                       bool showimplicit)
{
    if (looks_like_function(node))
        get_rule_expr(node, context, showimplicit);
    else
    {
        StringInfo  buf = context->buf;
 
        appendStringInfoString(buf, "CAST(");
        /* no point in showing any top-level implicit cast */
        get_rule_expr(node, context, false);
        appendStringInfo(buf, " AS %s)",
                         format_type_with_typemod(exprType(node),
                                                  exprTypmod(node)));
    }
}
 
/*
 * Helper function to identify node types that satisfy func_expr_windowless.
 * If in doubt, "false" is always a safe answer.
 */
static bool
looks_like_function(Node *node)
{
    if (node == NULL)
        return false;           /* probably shouldn't happen */
    switch (nodeTag(node))
    {
        case T_FuncExpr:
            /* OK, unless it's going to deparse as a cast */
            return (((FuncExpr *) node)->funcformat == COERCE_EXPLICIT_CALL ||
                    ((FuncExpr *) node)->funcformat == COERCE_SQL_SYNTAX);
        case T_NullIfExpr:
        case T_CoalesceExpr:
        case T_MinMaxExpr:
        case T_SQLValueFunction:
        case T_XmlExpr:
        case T_JsonExpr:
            /* these are all accepted by func_expr_common_subexpr */
            return true;
        default:
            break;
    }
    return false;
}
 
 
/*
 * get_oper_expr            - Parse back an OpExpr node
 */
static void
get_oper_expr(OpExpr *expr, deparse_context *context)
{
    StringInfo  buf = context->buf;
    Oid         opno = expr->opno;
    List       *args = expr->args;
 
    if (!PRETTY_PAREN(context))
        appendStringInfoChar(buf, '(');
    if (list_length(args) == 2)
    {
        /* binary operator */
        Node       *arg1 = (Node *) linitial(args);
        Node       *arg2 = (Node *) lsecond(args);
 
        get_rule_expr_paren(arg1, context, true, (Node *) expr);
        appendStringInfo(buf, " %s ",
                         generate_operator_name(opno,
                                                exprType(arg1),
                                                exprType(arg2)));
        get_rule_expr_paren(arg2, context, true, (Node *) expr);
    }
    else
    {
        /* prefix operator */
        Node       *arg = (Node *) linitial(args);
 
        appendStringInfo(buf, "%s ",
                         generate_operator_name(opno,
                                                InvalidOid,
                                                exprType(arg)));
        get_rule_expr_paren(arg, context, true, (Node *) expr);
    }
    if (!PRETTY_PAREN(context))
        appendStringInfoChar(buf, ')');
}
 
/*
 * get_func_expr            - Parse back a FuncExpr node
 */
static void
get_func_expr(FuncExpr *expr, deparse_context *context,
              bool showimplicit)
{
    StringInfo  buf = context->buf;
    Oid         funcoid = expr->funcid;
    Oid         argtypes[FUNC_MAX_ARGS];
    int         nargs;
    List       *argnames;
    bool        use_variadic;
    ListCell   *l;
 
    /*
     * If the function call came from an implicit coercion, then just show the
     * first argument --- unless caller wants to see implicit coercions.
     */
    if (expr->funcformat == COERCE_IMPLICIT_CAST && !showimplicit)
    {
        get_rule_expr_paren((Node *) linitial(expr->args), context,
                            false, (Node *) expr);
        return;
    }
 
    /*
     * If the function call came from a cast, then show the first argument
     * plus an explicit cast operation.
     */
    if (expr->funcformat == COERCE_EXPLICIT_CAST ||
        expr->funcformat == COERCE_IMPLICIT_CAST)
    {
        Node       *arg = linitial(expr->args);
        Oid         rettype = expr->funcresulttype;
        int32       coercedTypmod;
 
        /* Get the typmod if this is a length-coercion function */
        (void) exprIsLengthCoercion((Node *) expr, &coercedTypmod);
 
        get_coercion_expr(arg, context,
                          rettype, coercedTypmod,
                          (Node *) expr);
 
        return;
    }
 
    /*
     * If the function was called using one of the SQL spec's random special
     * syntaxes, try to reproduce that.  If we don't recognize the function,
     * fall through.
     */
    if (expr->funcformat == COERCE_SQL_SYNTAX)
    {
        if (get_func_sql_syntax(expr, context))
            return;
    }
 
    /*
     * Normal function: display as proname(args).  First we need to extract
     * the argument datatypes.
     */
    if (list_length(expr->args) > FUNC_MAX_ARGS)
        ereport(ERROR,
                (errcode(ERRCODE_TOO_MANY_ARGUMENTS),
                 errmsg("too many arguments")));
    nargs = 0;
    argnames = NIL;
    foreach(l, expr->args)
    {
        Node       *arg = (Node *) lfirst(l);
 
        if (IsA(arg, NamedArgExpr))
            argnames = lappend(argnames, ((NamedArgExpr *) arg)->name);
        argtypes[nargs] = exprType(arg);
        nargs++;
    }
 
    appendStringInfo(buf, "%s(",
                     generate_function_name(funcoid, nargs,
                                            argnames, argtypes,
                                            expr->funcvariadic,
                                            &use_variadic,
                                            context->inGroupBy));
    nargs = 0;
    foreach(l, expr->args)
    {
        if (nargs++ > 0)
            appendStringInfoString(buf, ", ");
        if (use_variadic && lnext(expr->args, l) == NULL)
            appendStringInfoString(buf, "VARIADIC ");
        get_rule_expr((Node *) lfirst(l), context, true);
    }
    appendStringInfoChar(buf, ')');
}
 
/*
 * get_agg_expr         - Parse back an Aggref node
 */
static void
get_agg_expr(Aggref *aggref, deparse_context *context,
             Aggref *original_aggref)
{
    get_agg_expr_helper(aggref, context, original_aggref, NULL, NULL,
                        false);
}
 
/*
 * get_agg_expr_helper      - subroutine for get_agg_expr and
 *                          get_json_agg_constructor
 */
static void
get_agg_expr_helper(Aggref *aggref, deparse_context *context,
                    Aggref *original_aggref, const char *funcname,
                    const char *options, bool is_json_objectagg)
{
    StringInfo  buf = context->buf;
    Oid         argtypes[FUNC_MAX_ARGS];
    int         nargs;
    bool        use_variadic = false;
 
    /*
     * For a combining aggregate, we look up and deparse the corresponding
     * partial aggregate instead.  This is necessary because our input
     * argument list has been replaced; the new argument list always has just
     * one element, which will point to a partial Aggref that supplies us with
     * transition states to combine.
     */
    if (DO_AGGSPLIT_COMBINE(aggref->aggsplit))
    {
        TargetEntry *tle;
 
        Assert(list_length(aggref->args) == 1);
        tle = linitial_node(TargetEntry, aggref->args);
        resolve_special_varno((Node *) tle->expr, context,
                              get_agg_combine_expr, original_aggref);
        return;
    }
 
    /*
     * Mark as PARTIAL, if appropriate.  We look to the original aggref so as
     * to avoid printing this when recursing from the code just above.
     */
    if (DO_AGGSPLIT_SKIPFINAL(original_aggref->aggsplit))
        appendStringInfoString(buf, "PARTIAL ");
 
    /* Extract the argument types as seen by the parser */
    nargs = get_aggregate_argtypes(aggref, argtypes);
 
    if (!funcname)
        funcname = generate_function_name(aggref->aggfnoid, nargs, NIL,
                                          argtypes, aggref->aggvariadic,
                                          &use_variadic,
                                          context->inGroupBy);
 
    /* Print the aggregate name, schema-qualified if needed */
    appendStringInfo(buf, "%s(%s", funcname,
                     (aggref->aggdistinct != NIL) ? "DISTINCT " : "");
 
    if (AGGKIND_IS_ORDERED_SET(aggref->aggkind))
    {
        /*
         * Ordered-set aggregates do not use "*" syntax.  Also, we needn't
         * worry about inserting VARIADIC.  So we can just dump the direct
         * args as-is.
         */
        Assert(!aggref->aggvariadic);
        get_rule_expr((Node *) aggref->aggdirectargs, context, true);
        Assert(aggref->aggorder != NIL);
        appendStringInfoString(buf, ") WITHIN GROUP (ORDER BY ");
        get_rule_orderby(aggref->aggorder, aggref->args, false, context);
    }
    else
    {
        /* aggstar can be set only in zero-argument aggregates */
        if (aggref->aggstar)
            appendStringInfoChar(buf, '*');
        else
        {
            ListCell   *l;
            int         i;
 
            i = 0;
            foreach(l, aggref->args)
            {
                TargetEntry *tle = (TargetEntry *) lfirst(l);
                Node       *arg = (Node *) tle->expr;
 
                Assert(!IsA(arg, NamedArgExpr));
                if (tle->resjunk)
                    continue;
                if (i++ > 0)
                {
                    if (is_json_objectagg)
                    {
                        /*
                         * the ABSENT ON NULL and WITH UNIQUE args are printed
                         * separately, so ignore them here
                         */
                        if (i > 2)
                            break;
 
                        appendStringInfoString(buf, " : ");
                    }
                    else
                        appendStringInfoString(buf, ", ");
                }
                if (use_variadic && i == nargs)
                    appendStringInfoString(buf, "VARIADIC ");
                get_rule_expr(arg, context, true);
            }
        }
 
        if (aggref->aggorder != NIL)
        {
            appendStringInfoString(buf, " ORDER BY ");
            get_rule_orderby(aggref->aggorder, aggref->args, false, context);
        }
    }
 
    if (options)
        appendStringInfoString(buf, options);
 
    if (aggref->aggfilter != NULL)
    {
        appendStringInfoString(buf, ") FILTER (WHERE ");
        get_rule_expr((Node *) aggref->aggfilter, context, false);
    }
 
    appendStringInfoChar(buf, ')');
}
 
/*
 * This is a helper function for get_agg_expr().  It's used when we deparse
 * a combining Aggref; resolve_special_varno locates the corresponding partial
 * Aggref and then calls this.
 */
static void
get_agg_combine_expr(Node *node, deparse_context *context, void *callback_arg)
{
    Aggref     *aggref;
    Aggref     *original_aggref = callback_arg;
 
    if (!IsA(node, Aggref))
        elog(ERROR, "combining Aggref does not point to an Aggref");
 
    aggref = (Aggref *) node;
    get_agg_expr(aggref, context, original_aggref);
}
 
/*
 * get_windowfunc_expr  - Parse back a WindowFunc node
 */
static void
get_windowfunc_expr(WindowFunc *wfunc, deparse_context *context)
{
    get_windowfunc_expr_helper(wfunc, context, NULL, NULL, false);
}
 
 
/*
 * get_windowfunc_expr_helper   - subroutine for get_windowfunc_expr and
 *                              get_json_agg_constructor
 */
static void
get_windowfunc_expr_helper(WindowFunc *wfunc, deparse_context *context,
                           const char *funcname, const char *options,
                           bool is_json_objectagg)
{
    StringInfo  buf = context->buf;
    Oid         argtypes[FUNC_MAX_ARGS];
    int         nargs;
    List       *argnames;
    ListCell   *l;
 
    if (list_length(wfunc->args) > FUNC_MAX_ARGS)
        ereport(ERROR,
                (errcode(ERRCODE_TOO_MANY_ARGUMENTS),
                 errmsg("too many arguments")));
    nargs = 0;
    argnames = NIL;
    foreach(l, wfunc->args)
    {
        Node       *arg = (Node *) lfirst(l);
 
        if (IsA(arg, NamedArgExpr))
            argnames = lappend(argnames, ((NamedArgExpr *) arg)->name);
        argtypes[nargs] = exprType(arg);
        nargs++;
    }
 
    if (!funcname)
        funcname = generate_function_name(wfunc->winfnoid, nargs, argnames,
                                          argtypes, false, NULL,
                                          context->inGroupBy);
 
    appendStringInfo(buf, "%s(", funcname);
 
    /* winstar can be set only in zero-argument aggregates */
    if (wfunc->winstar)
        appendStringInfoChar(buf, '*');
    else
    {
        if (is_json_objectagg)
        {
            get_rule_expr((Node *) linitial(wfunc->args), context, false);
            appendStringInfoString(buf, " : ");
            get_rule_expr((Node *) lsecond(wfunc->args), context, false);
        }
        else
            get_rule_expr((Node *) wfunc->args, context, true);
    }
 
    if (options)
        appendStringInfoString(buf, options);
 
    if (wfunc->aggfilter != NULL)
    {
        appendStringInfoString(buf, ") FILTER (WHERE ");
        get_rule_expr((Node *) wfunc->aggfilter, context, false);
    }
 
    appendStringInfoString(buf, ") OVER ");
 
    if (context->windowClause)
    {
        /* Query-decompilation case: search the windowClause list */
        foreach(l, context->windowClause)
        {
            WindowClause *wc = (WindowClause *) lfirst(l);
 
            if (wc->winref == wfunc->winref)
            {
                if (wc->name)
                    appendStringInfoString(buf, quote_identifier(wc->name));
                else
                    get_rule_windowspec(wc, context->targetList, context);
                break;
            }
        }
        if (l == NULL)
            elog(ERROR, "could not find window clause for winref %u",
                 wfunc->winref);
    }
    else
    {
        /*
         * In EXPLAIN, search the namespace stack for a matching WindowAgg
         * node (probably it's always the first entry), and print winname.
         */
        foreach(l, context->namespaces)
        {
            deparse_namespace *dpns = (deparse_namespace *) lfirst(l);
 
            if (dpns->plan && IsA(dpns->plan, WindowAgg))
            {
                WindowAgg  *wagg = (WindowAgg *) dpns->plan;
 
                if (wagg->winref == wfunc->winref)
                {
                    appendStringInfoString(buf, quote_identifier(wagg->winname));
                    break;
                }
            }
        }
        if (l == NULL)
            elog(ERROR, "could not find window clause for winref %u",
                 wfunc->winref);
    }
}
 
/*
 * get_func_sql_syntax      - Parse back a SQL-syntax function call
 *
 * Returns true if we successfully deparsed, false if we did not
 * recognize the function.
 */
static bool
get_func_sql_syntax(FuncExpr *expr, deparse_context *context)
{
    StringInfo  buf = context->buf;
    Oid         funcoid = expr->funcid;
 
    switch (funcoid)
    {
        case F_TIMEZONE_INTERVAL_TIMESTAMP:
        case F_TIMEZONE_INTERVAL_TIMESTAMPTZ:
        case F_TIMEZONE_INTERVAL_TIMETZ:
        case F_TIMEZONE_TEXT_TIMESTAMP:
        case F_TIMEZONE_TEXT_TIMESTAMPTZ:
        case F_TIMEZONE_TEXT_TIMETZ:
            /* AT TIME ZONE ... note reversed argument order */
            appendStringInfoChar(buf, '(');
            get_rule_expr_paren((Node *) lsecond(expr->args), context, false,
                                (Node *) expr);
            appendStringInfoString(buf, " AT TIME ZONE ");
            get_rule_expr_paren((Node *) linitial(expr->args), context, false,
                                (Node *) expr);
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_TIMEZONE_TIMESTAMP:
        case F_TIMEZONE_TIMESTAMPTZ:
        case F_TIMEZONE_TIMETZ:
            /* AT LOCAL */
            appendStringInfoChar(buf, '(');
            get_rule_expr_paren((Node *) linitial(expr->args), context, false,
                                (Node *) expr);
            appendStringInfoString(buf, " AT LOCAL)");
            return true;
 
        case F_OVERLAPS_TIMESTAMPTZ_INTERVAL_TIMESTAMPTZ_INTERVAL:
        case F_OVERLAPS_TIMESTAMPTZ_INTERVAL_TIMESTAMPTZ_TIMESTAMPTZ:
        case F_OVERLAPS_TIMESTAMPTZ_TIMESTAMPTZ_TIMESTAMPTZ_INTERVAL:
        case F_OVERLAPS_TIMESTAMPTZ_TIMESTAMPTZ_TIMESTAMPTZ_TIMESTAMPTZ:
        case F_OVERLAPS_TIMESTAMP_INTERVAL_TIMESTAMP_INTERVAL:
        case F_OVERLAPS_TIMESTAMP_INTERVAL_TIMESTAMP_TIMESTAMP:
        case F_OVERLAPS_TIMESTAMP_TIMESTAMP_TIMESTAMP_INTERVAL:
        case F_OVERLAPS_TIMESTAMP_TIMESTAMP_TIMESTAMP_TIMESTAMP:
        case F_OVERLAPS_TIMETZ_TIMETZ_TIMETZ_TIMETZ:
        case F_OVERLAPS_TIME_INTERVAL_TIME_INTERVAL:
        case F_OVERLAPS_TIME_INTERVAL_TIME_TIME:
        case F_OVERLAPS_TIME_TIME_TIME_INTERVAL:
        case F_OVERLAPS_TIME_TIME_TIME_TIME:
            /* (x1, x2) OVERLAPS (y1, y2) */
            appendStringInfoString(buf, "((");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoString(buf, ", ");
            get_rule_expr((Node *) lsecond(expr->args), context, false);
            appendStringInfoString(buf, ") OVERLAPS (");
            get_rule_expr((Node *) lthird(expr->args), context, false);
            appendStringInfoString(buf, ", ");
            get_rule_expr((Node *) lfourth(expr->args), context, false);
            appendStringInfoString(buf, "))");
            return true;
 
        case F_EXTRACT_TEXT_DATE:
        case F_EXTRACT_TEXT_TIME:
        case F_EXTRACT_TEXT_TIMETZ:
        case F_EXTRACT_TEXT_TIMESTAMP:
        case F_EXTRACT_TEXT_TIMESTAMPTZ:
        case F_EXTRACT_TEXT_INTERVAL:
            /* EXTRACT (x FROM y) */
            appendStringInfoString(buf, "EXTRACT(");
            {
                Const      *con = (Const *) linitial(expr->args);
 
                Assert(IsA(con, Const) &&
                       con->consttype == TEXTOID &&
                       !con->constisnull);
                appendStringInfoString(buf, TextDatumGetCString(con->constvalue));
            }
            appendStringInfoString(buf, " FROM ");
            get_rule_expr((Node *) lsecond(expr->args), context, false);
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_IS_NORMALIZED:
            /* IS xxx NORMALIZED */
            appendStringInfoChar(buf, '(');
            get_rule_expr_paren((Node *) linitial(expr->args), context, false,
                                (Node *) expr);
            appendStringInfoString(buf, " IS");
            if (list_length(expr->args) == 2)
            {
                Const      *con = (Const *) lsecond(expr->args);
 
                Assert(IsA(con, Const) &&
                       con->consttype == TEXTOID &&
                       !con->constisnull);
                appendStringInfo(buf, " %s",
                                 TextDatumGetCString(con->constvalue));
            }
            appendStringInfoString(buf, " NORMALIZED)");
            return true;
 
        case F_PG_COLLATION_FOR:
            /* COLLATION FOR */
            appendStringInfoString(buf, "COLLATION FOR (");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_NORMALIZE:
            /* NORMALIZE() */
            appendStringInfoString(buf, "NORMALIZE(");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            if (list_length(expr->args) == 2)
            {
                Const      *con = (Const *) lsecond(expr->args);
 
                Assert(IsA(con, Const) &&
                       con->consttype == TEXTOID &&
                       !con->constisnull);
                appendStringInfo(buf, ", %s",
                                 TextDatumGetCString(con->constvalue));
            }
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_OVERLAY_BIT_BIT_INT4:
        case F_OVERLAY_BIT_BIT_INT4_INT4:
        case F_OVERLAY_BYTEA_BYTEA_INT4:
        case F_OVERLAY_BYTEA_BYTEA_INT4_INT4:
        case F_OVERLAY_TEXT_TEXT_INT4:
        case F_OVERLAY_TEXT_TEXT_INT4_INT4:
            /* OVERLAY() */
            appendStringInfoString(buf, "OVERLAY(");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoString(buf, " PLACING ");
            get_rule_expr((Node *) lsecond(expr->args), context, false);
            appendStringInfoString(buf, " FROM ");
            get_rule_expr((Node *) lthird(expr->args), context, false);
            if (list_length(expr->args) == 4)
            {
                appendStringInfoString(buf, " FOR ");
                get_rule_expr((Node *) lfourth(expr->args), context, false);
            }
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_POSITION_BIT_BIT:
        case F_POSITION_BYTEA_BYTEA:
        case F_POSITION_TEXT_TEXT:
            /* POSITION() ... extra parens since args are b_expr not a_expr */
            appendStringInfoString(buf, "POSITION((");
            get_rule_expr((Node *) lsecond(expr->args), context, false);
            appendStringInfoString(buf, ") IN (");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoString(buf, "))");
            return true;
 
        case F_SUBSTRING_BIT_INT4:
        case F_SUBSTRING_BIT_INT4_INT4:
        case F_SUBSTRING_BYTEA_INT4:
        case F_SUBSTRING_BYTEA_INT4_INT4:
        case F_SUBSTRING_TEXT_INT4:
        case F_SUBSTRING_TEXT_INT4_INT4:
            /* SUBSTRING FROM/FOR (i.e., integer-position variants) */
            appendStringInfoString(buf, "SUBSTRING(");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoString(buf, " FROM ");
            get_rule_expr((Node *) lsecond(expr->args), context, false);
            if (list_length(expr->args) == 3)
            {
                appendStringInfoString(buf, " FOR ");
                get_rule_expr((Node *) lthird(expr->args), context, false);
            }
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_SUBSTRING_TEXT_TEXT_TEXT:
            /* SUBSTRING SIMILAR/ESCAPE */
            appendStringInfoString(buf, "SUBSTRING(");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoString(buf, " SIMILAR ");
            get_rule_expr((Node *) lsecond(expr->args), context, false);
            appendStringInfoString(buf, " ESCAPE ");
            get_rule_expr((Node *) lthird(expr->args), context, false);
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_BTRIM_BYTEA_BYTEA:
        case F_BTRIM_TEXT:
        case F_BTRIM_TEXT_TEXT:
            /* TRIM() */
            appendStringInfoString(buf, "TRIM(BOTH");
            if (list_length(expr->args) == 2)
            {
                appendStringInfoChar(buf, ' ');
                get_rule_expr((Node *) lsecond(expr->args), context, false);
            }
            appendStringInfoString(buf, " FROM ");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_LTRIM_BYTEA_BYTEA:
        case F_LTRIM_TEXT:
        case F_LTRIM_TEXT_TEXT:
            /* TRIM() */
            appendStringInfoString(buf, "TRIM(LEADING");
            if (list_length(expr->args) == 2)
            {
                appendStringInfoChar(buf, ' ');
                get_rule_expr((Node *) lsecond(expr->args), context, false);
            }
            appendStringInfoString(buf, " FROM ");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_RTRIM_BYTEA_BYTEA:
        case F_RTRIM_TEXT:
        case F_RTRIM_TEXT_TEXT:
            /* TRIM() */
            appendStringInfoString(buf, "TRIM(TRAILING");
            if (list_length(expr->args) == 2)
            {
                appendStringInfoChar(buf, ' ');
                get_rule_expr((Node *) lsecond(expr->args), context, false);
            }
            appendStringInfoString(buf, " FROM ");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoChar(buf, ')');
            return true;
 
        case F_SYSTEM_USER:
            appendStringInfoString(buf, "SYSTEM_USER");
            return true;
 
        case F_XMLEXISTS:
            /* XMLEXISTS ... extra parens because args are c_expr */
            appendStringInfoString(buf, "XMLEXISTS((");
            get_rule_expr((Node *) linitial(expr->args), context, false);
            appendStringInfoString(buf, ") PASSING (");
            get_rule_expr((Node *) lsecond(expr->args), context, false);
            appendStringInfoString(buf, "))");
            return true;
    }
    return false;
}
 
/* ----------
 * get_coercion_expr
 *
 *  Make a string representation of a value coerced to a specific type
 * ----------
 */
static void
get_coercion_expr(Node *arg, deparse_context *context,
                  Oid resulttype, int32 resulttypmod,
                  Node *parentNode)
{
    StringInfo  buf = context->buf;
 
    /*
     * Since parse_coerce.c doesn't immediately collapse application of
     * length-coercion functions to constants, what we'll typically see in
     * such cases is a Const with typmod -1 and a length-coercion function
     * right above it.  Avoid generating redundant output. However, beware of
     * suppressing casts when the user actually wrote something like
     * 'foo'::text::char(3).
     *
     * Note: it might seem that we are missing the possibility of needing to
     * print a COLLATE clause for such a Const.  However, a Const could only
     * have nondefault collation in a post-constant-folding tree, in which the
     * length coercion would have been folded too.  See also the special
     * handling of CollateExpr in coerce_to_target_type(): any collation
     * marking will be above the coercion node, not below it.
     */
    if (arg && IsA(arg, Const) &&
        ((Const *) arg)->consttype == resulttype &&
        ((Const *) arg)->consttypmod == -1)
    {
        /* Show the constant without normal ::typename decoration */
        get_const_expr((Const *) arg, context, -1);
    }
    else
    {
        if (!PRETTY_PAREN(context))
            appendStringInfoChar(buf, '(');
        get_rule_expr_paren(arg, context, false, parentNode);
        if (!PRETTY_PAREN(context))
            appendStringInfoChar(buf, ')');
    }
 
    /*
     * Never emit resulttype(arg) functional notation. A pg_proc entry could
     * take precedence, and a resulttype in pg_temp would require schema
     * qualification that format_type_with_typemod() would usually omit. We've
     * standardized on arg::resulttype, but CAST(arg AS resulttype) notation
     * would work fine.
     */
    appendStringInfo(buf, "::%s",
                     format_type_with_typemod(resulttype, resulttypmod));
}
 
/* ----------
 * get_const_expr
 *
 *  Make a string representation of a Const
 *
 * showtype can be -1 to never show "::typename" decoration, or +1 to always
 * show it, or 0 to show it only if the constant wouldn't be assumed to be
 * the right type by default.
 *
 * If the Const's collation isn't default for its type, show that too.
 * We mustn't do this when showtype is -1 (since that means the caller will
 * print "::typename", and we can't put a COLLATE clause in between).  It's
 * caller's responsibility that collation isn't missed in such cases.
 * ----------
 */
static void
get_const_expr(Const *constval, deparse_context *context, int showtype)
{
    StringInfo  buf = context->buf;
    Oid         typoutput;
    bool        typIsVarlena;
    char       *extval;
    bool        needlabel = false;
 
    if (constval->constisnull)
    {
        /*
         * Always label the type of a NULL constant to prevent misdecisions
         * about type when reparsing.
         */
        appendStringInfoString(buf, "NULL");
        if (showtype >= 0)
        {
            appendStringInfo(buf, "::%s",
                             format_type_with_typemod(constval->consttype,
                                                      constval->consttypmod));
            get_const_collation(constval, context);
        }
        return;
    }
 
    getTypeOutputInfo(constval->consttype,
                      &typoutput, &typIsVarlena);
 
    extval = OidOutputFunctionCall(typoutput, constval->constvalue);
 
    switch (constval->consttype)
    {
        case INT4OID:
 
            /*
             * INT4 can be printed without any decoration, unless it is
             * negative; in that case print it as '-nnn'::integer to ensure
             * that the output will re-parse as a constant, not as a constant
             * plus operator.  In most cases we could get away with printing
             * (-nnn) instead, because of the way that gram.y handles negative
             * literals; but that doesn't work for INT_MIN, and it doesn't
             * seem that much prettier anyway.
             */
            if (extval[0] != '-')
                appendStringInfoString(buf, extval);
            else
            {
                appendStringInfo(buf, "'%s'", extval);
                needlabel = true;   /* we must attach a cast */
            }
            break;
 
        case NUMERICOID:
 
            /*
             * NUMERIC can be printed without quotes if it looks like a float
             * constant (not an integer, and not Infinity or NaN) and doesn't
             * have a leading sign (for the same reason as for INT4).
             */
            if (isdigit((unsigned char) extval[0]) &&
                strcspn(extval, "eE.") != strlen(extval))
            {
                appendStringInfoString(buf, extval);
            }
            else
            {
                appendStringInfo(buf, "'%s'", extval);
                needlabel = true;   /* we must attach a cast */
            }
            break;
 
        case BOOLOID:
            if (strcmp(extval, "t") == 0)
                appendStringInfoString(buf, "true");
            else
                appendStringInfoString(buf, "false");
            break;
 
        default:
            simple_quote_literal(buf, extval);
            break;
    }
 
    pfree(extval);
 
    if (showtype < 0)
        return;
 
    /*
     * For showtype == 0, append ::typename unless the constant will be
     * implicitly typed as the right type when it is read in.
     *
     * XXX this code has to be kept in sync with the behavior of the parser,
     * especially make_const.
     */
    switch (constval->consttype)
    {
        case BOOLOID:
        case UNKNOWNOID:
            /* These types can be left unlabeled */
            needlabel = false;
            break;
        case INT4OID:
            /* We determined above whether a label is needed */
            break;
        case NUMERICOID:
 
            /*
             * Float-looking constants will be typed as numeric, which we
             * checked above; but if there's a nondefault typmod we need to
             * show it.
             */
            needlabel |= (constval->consttypmod >= 0);
            break;
        default:
            needlabel = true;
            break;
    }
    if (needlabel || showtype > 0)
        appendStringInfo(buf, "::%s",
                         format_type_with_typemod(constval->consttype,
                                                  constval->consttypmod));
 
    get_const_collation(constval, context);
}
 
/*
 * helper for get_const_expr: append COLLATE if needed
 */
static void
get_const_collation(Const *constval, deparse_context *context)
{
    StringInfo  buf = context->buf;
 
    if (OidIsValid(constval->constcollid))
    {
        Oid         typcollation = get_typcollation(constval->consttype);
 
        if (constval->constcollid != typcollation)
        {
            appendStringInfo(buf, " COLLATE %s",
                             generate_collation_name(constval->constcollid));
        }
    }
}
 
/*
 * get_json_path_spec       - Parse back a JSON path specification
 */
static void
get_json_path_spec(Node *path_spec, deparse_context *context, bool showimplicit)
{
    if (IsA(path_spec, Const))
        get_const_expr((Const *) path_spec, context, -1);
    else
        get_rule_expr(path_spec, context, showimplicit);
}
 
/*
 * get_json_format          - Parse back a JsonFormat node
 */
static void
get_json_format(JsonFormat *format, StringInfo buf)
{
    if (format->format_type == JS_FORMAT_DEFAULT)
        return;
 
    appendStringInfoString(buf,
                           format->format_type == JS_FORMAT_JSONB ?
                           " FORMAT JSONB" : " FORMAT JSON");
 
    if (format->encoding != JS_ENC_DEFAULT)
    {
        const char *encoding;
 
        encoding =
            format->encoding == JS_ENC_UTF16 ? "UTF16" :
            format->encoding == JS_ENC_UTF32 ? "UTF32" : "UTF8";
 
        appendStringInfo(buf, " ENCODING %s", encoding);
    }
}
 
/*
 * get_json_returning       - Parse back a JsonReturning structure
 */
static void
get_json_returning(JsonReturning *returning, StringInfo buf,
                   bool json_format_by_default)
{
    if (!OidIsValid(returning->typid))
        return;
 
    appendStringInfo(buf, " RETURNING %s",
                     format_type_with_typemod(returning->typid,
                                              returning->typmod));
 
    if (!json_format_by_default ||
        returning->format->format_type !=
        (returning->typid == JSONBOID ? JS_FORMAT_JSONB : JS_FORMAT_JSON))
        get_json_format(returning->format, buf);
}
 
/*
 * get_json_constructor     - Parse back a JsonConstructorExpr node
 */
static void
get_json_constructor(JsonConstructorExpr *ctor, deparse_context *context,
                     bool showimplicit)
{
    StringInfo  buf = context->buf;
    const char *funcname;
    bool        is_json_object;
    int         curridx;
    ListCell   *lc;
 
    if (ctor->type == JSCTOR_JSON_OBJECTAGG)
    {
        get_json_agg_constructor(ctor, context, "JSON_OBJECTAGG", true);
        return;
    }
    else if (ctor->type == JSCTOR_JSON_ARRAYAGG)
    {
        get_json_agg_constructor(ctor, context, "JSON_ARRAYAGG", false);
        return;
    }
 
    switch (ctor->type)
    {
        case JSCTOR_JSON_OBJECT:
            funcname = "JSON_OBJECT";
            break;
        case JSCTOR_JSON_ARRAY:
            funcname = "JSON_ARRAY";
            break;
        case JSCTOR_JSON_PARSE:
            funcname = "JSON";
            break;
        case JSCTOR_JSON_SCALAR:
            funcname = "JSON_SCALAR";
            break;
        case JSCTOR_JSON_SERIALIZE:
            funcname = "JSON_SERIALIZE";
            break;
        default:
            elog(ERROR, "invalid JsonConstructorType %d", ctor->type);
    }
 
    appendStringInfo(buf, "%s(", funcname);
 
    is_json_object = ctor->type == JSCTOR_JSON_OBJECT;
    foreach(lc, ctor->args)
    {
        curridx = foreach_current_index(lc);
        if (curridx > 0)
        {
            const char *sep;
 
            sep = (is_json_object && (curridx % 2) != 0) ? " : " : ", ";
            appendStringInfoString(buf, sep);
        }
 
        get_rule_expr((Node *) lfirst(lc), context, true);
    }
 
    get_json_constructor_options(ctor, buf);
    appendStringInfoChar(buf, ')');
}
 
/*
 * Append options, if any, to the JSON constructor being deparsed
 */
static void
get_json_constructor_options(JsonConstructorExpr *ctor, StringInfo buf)
{
    if (ctor->absent_on_null)
    {
        if (ctor->type == JSCTOR_JSON_OBJECT ||
            ctor->type == JSCTOR_JSON_OBJECTAGG)
            appendStringInfoString(buf, " ABSENT ON NULL");
    }
    else
    {
        if (ctor->type == JSCTOR_JSON_ARRAY ||
            ctor->type == JSCTOR_JSON_ARRAYAGG)
            appendStringInfoString(buf, " NULL ON NULL");
    }
 
    if (ctor->unique)
        appendStringInfoString(buf, " WITH UNIQUE KEYS");
 
    /*
     * Append RETURNING clause if needed; JSON() and JSON_SCALAR() don't
     * support one.
     */
    if (ctor->type != JSCTOR_JSON_PARSE && ctor->type != JSCTOR_JSON_SCALAR)
        get_json_returning(ctor->returning, buf, true);
}
 
/*
 * get_json_agg_constructor - Parse back an aggregate JsonConstructorExpr node
 */
static void
get_json_agg_constructor(JsonConstructorExpr *ctor, deparse_context *context,
                         const char *funcname, bool is_json_objectagg)
{
    StringInfoData options;
 
    initStringInfo(&options);
    get_json_constructor_options(ctor, &options);
 
    if (IsA(ctor->func, Aggref))
        get_agg_expr_helper((Aggref *) ctor->func, context,
                            (Aggref *) ctor->func,
                            funcname, options.data, is_json_objectagg);
    else if (IsA(ctor->func, WindowFunc))
        get_windowfunc_expr_helper((WindowFunc *) ctor->func, context,
                                   funcname, options.data,
                                   is_json_objectagg);
    else
        elog(ERROR, "invalid JsonConstructorExpr underlying node type: %d",
             nodeTag(ctor->func));
}
 
/*
 * simple_quote_literal - Format a string as a SQL literal, append to buf
 */
static void
simple_quote_literal(StringInfo buf, const char *val)
{
    const char *valptr;
 
    /*
     * We form the string literal according to the prevailing setting of
     * standard_conforming_strings; we never use E''. User is responsible for
     * making sure result is used correctly.
     */
    appendStringInfoChar(buf, '\'');
    for (valptr = val; *valptr; valptr++)
    {
        char        ch = *valptr;
 
        if (SQL_STR_DOUBLE(ch, !standard_conforming_strings))
            appendStringInfoChar(buf, ch);
        appendStringInfoChar(buf, ch);
    }
    appendStringInfoChar(buf, '\'');
}
 
 
/* ----------
 * get_sublink_expr         - Parse back a sublink
 * ----------
 */
static void
get_sublink_expr(SubLink *sublink, deparse_context *context)
{
    StringInfo  buf = context->buf;
    Query      *query = (Query *) (sublink->subselect);
    char       *opname = NULL;
    bool        need_paren;
 
    if (sublink->subLinkType == ARRAY_SUBLINK)
        appendStringInfoString(buf, "ARRAY(");
    else
        appendStringInfoChar(buf, '(');
 
    /*
     * Note that we print the name of only the first operator, when there are
     * multiple combining operators.  This is an approximation that could go
     * wrong in various scenarios (operators in different schemas, renamed
     * operators, etc) but there is not a whole lot we can do about it, since
     * the syntax allows only one operator to be shown.
     */
    if (sublink->testexpr)
    {
        if (IsA(sublink->testexpr, OpExpr))
        {
            /* single combining operator */
            OpExpr     *opexpr = (OpExpr *) sublink->testexpr;
 
            get_rule_expr(linitial(opexpr->args), context, true);
            opname = generate_operator_name(opexpr->opno,
                                            exprType(linitial(opexpr->args)),
                                            exprType(lsecond(opexpr->args)));
        }
        else if (IsA(sublink->testexpr, BoolExpr))
        {
            /* multiple combining operators, = or <> cases */
            char       *sep;
            ListCell   *l;
 
            appendStringInfoChar(buf, '(');
            sep = "";
            foreach(l, ((BoolExpr *) sublink->testexpr)->args)
            {
                OpExpr     *opexpr = lfirst_node(OpExpr, l);
 
                appendStringInfoString(buf, sep);
                get_rule_expr(linitial(opexpr->args), context, true);
                if (!opname)
                    opname = generate_operator_name(opexpr->opno,
                                                    exprType(linitial(opexpr->args)),
                                                    exprType(lsecond(opexpr->args)));
                sep = ", ";
            }
            appendStringInfoChar(buf, ')');
        }
        else if (IsA(sublink->testexpr, RowCompareExpr))
        {
            /* multiple combining operators, < <= > >= cases */
            RowCompareExpr *rcexpr = (RowCompareExpr *) sublink->testexpr;
 
            appendStringInfoChar(buf, '(');
            get_rule_expr((Node *) rcexpr->largs, context, true);
            opname = generate_operator_name(linitial_oid(rcexpr->opnos),
                                            exprType(linitial(rcexpr->largs)),
                                            exprType(linitial(rcexpr->rargs)));
            appendStringInfoChar(buf, ')');
        }
        else
            elog(ERROR, "unrecognized testexpr type: %d",
                 (int) nodeTag(sublink->testexpr));
    }
 
    need_paren = true;
 
    switch (sublink->subLinkType)
    {
        case EXISTS_SUBLINK:
            appendStringInfoString(buf, "EXISTS ");
            break;
 
        case ANY_SUBLINK:
            if (strcmp(opname, "=") == 0)   /* Represent = ANY as IN */
                appendStringInfoString(buf, " IN ");
            else
                appendStringInfo(buf, " %s ANY ", opname);
            break;
 
        case ALL_SUBLINK:
            appendStringInfo(buf, " %s ALL ", opname);
            break;
 
        case ROWCOMPARE_SUBLINK:
            appendStringInfo(buf, " %s ", opname);
            break;
 
        case EXPR_SUBLINK:
        case MULTIEXPR_SUBLINK:
        case ARRAY_SUBLINK:
            need_paren = false;
            break;
 
        case CTE_SUBLINK:       /* shouldn't occur in a SubLink */
        default:
            elog(ERROR, "unrecognized sublink type: %d",
                 (int) sublink->subLinkType);
            break;
    }
 
    if (need_paren)
        appendStringInfoChar(buf, '(');
 
    get_query_def(query, buf, context->namespaces, NULL, false,
                  context->prettyFlags, context->wrapColumn,
                  context->indentLevel);
 
    if (need_paren)
        appendStringInfoString(buf, "))");
    else
        appendStringInfoChar(buf, ')');
}
 
 
/* ----------
 * get_xmltable         - Parse back a XMLTABLE function
 * ----------
 */
static void
get_xmltable(TableFunc *tf, deparse_context *context, bool showimplicit)
{
    StringInfo  buf = context->buf;
 
    appendStringInfoString(buf, "XMLTABLE(");
 
    if (tf->ns_uris != NIL)
    {
        ListCell   *lc1,
                   *lc2;
        bool        first = true;
 
        appendStringInfoString(buf, "XMLNAMESPACES (");
        forboth(lc1, tf->ns_uris, lc2, tf->ns_names)
        {
            Node       *expr = (Node *) lfirst(lc1);
            String     *ns_node = lfirst_node(String, lc2);
 
            if (!first)
                appendStringInfoString(buf, ", ");
            else
                first = false;
 
            if (ns_node != NULL)
            {
                get_rule_expr(expr, context, showimplicit);
                appendStringInfo(buf, " AS %s",
                                 quote_identifier(strVal(ns_node)));
            }
            else
            {
                appendStringInfoString(buf, "DEFAULT ");
                get_rule_expr(expr, context, showimplicit);
            }
        }
        appendStringInfoString(buf, "), ");
    }
 
    appendStringInfoChar(buf, '(');
    get_rule_expr((Node *) tf->rowexpr, context, showimplicit);
    appendStringInfoString(buf, ") PASSING (");
    get_rule_expr((Node *) tf->docexpr, context, showimplicit);
    appendStringInfoChar(buf, ')');
 
    if (tf->colexprs != NIL)
    {
        ListCell   *l1;
        ListCell   *l2;
        ListCell   *l3;
        ListCell   *l4;
        ListCell   *l5;
        int         colnum = 0;
 
        appendStringInfoString(buf, " COLUMNS ");
        forfive(l1, tf->colnames, l2, tf->coltypes, l3, tf->coltypmods,
                l4, tf->colexprs, l5, tf->coldefexprs)
        {
            char       *colname = strVal(lfirst(l1));
            Oid         typid = lfirst_oid(l2);
            int32       typmod = lfirst_int(l3);
            Node       *colexpr = (Node *) lfirst(l4);
            Node       *coldefexpr = (Node *) lfirst(l5);
            bool        ordinality = (tf->ordinalitycol == colnum);
            bool        notnull = bms_is_member(colnum, tf->notnulls);
 
            if (colnum > 0)
                appendStringInfoString(buf, ", ");
            colnum++;
 
            appendStringInfo(buf, "%s %s", quote_identifier(colname),
                             ordinality ? "FOR ORDINALITY" :
                             format_type_with_typemod(typid, typmod));
            if (ordinality)
                continue;
 
            if (coldefexpr != NULL)
            {
                appendStringInfoString(buf, " DEFAULT (");
                get_rule_expr((Node *) coldefexpr, context, showimplicit);
                appendStringInfoChar(buf, ')');
            }
            if (colexpr != NULL)
            {
                appendStringInfoString(buf, " PATH (");
                get_rule_expr((Node *) colexpr, context, showimplicit);
                appendStringInfoChar(buf, ')');
            }
            if (notnull)
                appendStringInfoString(buf, " NOT NULL");
        }
    }
 
    appendStringInfoChar(buf, ')');
}
 
/*
 * get_json_table_nested_columns - Parse back nested JSON_TABLE columns
 */
static void
get_json_table_nested_columns(TableFunc *tf, JsonTablePlan *plan,
                              deparse_context *context, bool showimplicit,
                              bool needcomma)
{
    if (IsA(plan, JsonTablePathScan))
    {
        JsonTablePathScan *scan = castNode(JsonTablePathScan, plan);
 
        if (needcomma)
            appendStringInfoChar(context->buf, ',');
 
        appendStringInfoChar(context->buf, ' ');
        appendContextKeyword(context, "NESTED PATH ", 0, 0, 0);
        get_const_expr(scan->path->value, context, -1);
        appendStringInfo(context->buf, " AS %s", quote_identifier(scan->path->name));
        get_json_table_columns(tf, scan, context, showimplicit);
    }
    else if (IsA(plan, JsonTableSiblingJoin))
    {
        JsonTableSiblingJoin *join = (JsonTableSiblingJoin *) plan;
 
        get_json_table_nested_columns(tf, join->lplan, context, showimplicit,
                                      needcomma);
        get_json_table_nested_columns(tf, join->rplan, context, showimplicit,
                                      true);
    }
}
 
/*
 * get_json_table_columns - Parse back JSON_TABLE columns
 */
static void
get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
                       deparse_context *context,
                       bool showimplicit)
{
    StringInfo  buf = context->buf;
    ListCell   *lc_colname;
    ListCell   *lc_coltype;
    ListCell   *lc_coltypmod;
    ListCell   *lc_colvalexpr;
    int         colnum = 0;
 
    appendStringInfoChar(buf, ' ');
    appendContextKeyword(context, "COLUMNS (", 0, 0, 0);
 
    if (PRETTY_INDENT(context))
        context->indentLevel += PRETTYINDENT_VAR;
 
    forfour(lc_colname, tf->colnames,
            lc_coltype, tf->coltypes,
            lc_coltypmod, tf->coltypmods,
            lc_colvalexpr, tf->colvalexprs)
    {
        char       *colname = strVal(lfirst(lc_colname));
        JsonExpr   *colexpr;
        Oid         typid;
        int32       typmod;
        bool        ordinality;
        JsonBehaviorType default_behavior;
 
        typid = lfirst_oid(lc_coltype);
        typmod = lfirst_int(lc_coltypmod);
        colexpr = castNode(JsonExpr, lfirst(lc_colvalexpr));
 
        /* Skip columns that don't belong to this scan. */
        if (scan->colMin < 0 || colnum < scan->colMin)
        {
            colnum++;
            continue;
        }
        if (colnum > scan->colMax)
            break;
 
        if (colnum > scan->colMin)
            appendStringInfoString(buf, ", ");
 
        colnum++;
 
        ordinality = !colexpr;
 
        appendContextKeyword(context, "", 0, 0, 0);
 
        appendStringInfo(buf, "%s %s", quote_identifier(colname),
                         ordinality ? "FOR ORDINALITY" :
                         format_type_with_typemod(typid, typmod));
        if (ordinality)
            continue;
 
        /*
         * Set default_behavior to guide get_json_expr_options() on whether to
         * to emit the ON ERROR / EMPTY clauses.
         */
        if (colexpr->op == JSON_EXISTS_OP)
        {
            appendStringInfoString(buf, " EXISTS");
            default_behavior = JSON_BEHAVIOR_FALSE;
        }
        else
        {
            if (colexpr->op == JSON_QUERY_OP)
            {
                char        typcategory;
                bool        typispreferred;
 
                get_type_category_preferred(typid, &typcategory, &typispreferred);
 
                if (typcategory == TYPCATEGORY_STRING)
                    appendStringInfoString(buf,
                                           colexpr->format->format_type == JS_FORMAT_JSONB ?
                                           " FORMAT JSONB" : " FORMAT JSON");
            }
 
            default_behavior = JSON_BEHAVIOR_NULL;
        }
 
        appendStringInfoString(buf, " PATH ");
 
        get_json_path_spec(colexpr->path_spec, context, showimplicit);
 
        get_json_expr_options(colexpr, context, default_behavior);
    }
 
    if (scan->child)
        get_json_table_nested_columns(tf, scan->child, context, showimplicit,
                                      scan->colMin >= 0);
 
    if (PRETTY_INDENT(context))
        context->indentLevel -= PRETTYINDENT_VAR;
 
    appendContextKeyword(context, ")", 0, 0, 0);
}
 
/* ----------
 * get_json_table           - Parse back a JSON_TABLE function
 * ----------
 */
static void
get_json_table(TableFunc *tf, deparse_context *context, bool showimplicit)
{
    StringInfo  buf = context->buf;
    JsonExpr   *jexpr = castNode(JsonExpr, tf->docexpr);
    JsonTablePathScan *root = castNode(JsonTablePathScan, tf->plan);
 
    appendStringInfoString(buf, "JSON_TABLE(");
 
    if (PRETTY_INDENT(context))
        context->indentLevel += PRETTYINDENT_VAR;
 
    appendContextKeyword(context, "", 0, 0, 0);
 
    get_rule_expr(jexpr->formatted_expr, context, showimplicit);
 
    appendStringInfoString(buf, ", ");
 
    get_const_expr(root->path->value, context, -1);
 
    appendStringInfo(buf, " AS %s", quote_identifier(root->path->name));
 
    if (jexpr->passing_values)
    {
        ListCell   *lc1,
                   *lc2;
        bool        needcomma = false;
 
        appendStringInfoChar(buf, ' ');
        appendContextKeyword(context, "PASSING ", 0, 0, 0);
 
        if (PRETTY_INDENT(context))
            context->indentLevel += PRETTYINDENT_VAR;
 
        forboth(lc1, jexpr->passing_names,
                lc2, jexpr->passing_values)
        {
            if (needcomma)
                appendStringInfoString(buf, ", ");
            needcomma = true;
 
            appendContextKeyword(context, "", 0, 0, 0);
 
            get_rule_expr((Node *) lfirst(lc2), context, false);
            appendStringInfo(buf, " AS %s",
                             quote_identifier((lfirst_node(String, lc1))->sval)
                );
        }
 
        if (PRETTY_INDENT(context))
            context->indentLevel -= PRETTYINDENT_VAR;
    }
 
    get_json_table_columns(tf, castNode(JsonTablePathScan, tf->plan), context,
                           showimplicit);
 
    if (jexpr->on_error->btype != JSON_BEHAVIOR_EMPTY_ARRAY)
        get_json_behavior(jexpr->on_error, context, "ERROR");
 
    if (PRETTY_INDENT(context))
        context->indentLevel -= PRETTYINDENT_VAR;
 
    appendContextKeyword(context, ")", 0, 0, 0);
}
 
/* ----------
 * get_tablefunc            - Parse back a table function
 * ----------
 */
static void
get_tablefunc(TableFunc *tf, deparse_context *context, bool showimplicit)
{
    /* XMLTABLE and JSON_TABLE are the only existing implementations.  */
 
    if (tf->functype == TFT_XMLTABLE)
        get_xmltable(tf, context, showimplicit);
    else if (tf->functype == TFT_JSON_TABLE)
        get_json_table(tf, context, showimplicit);
}
 
/* ----------
 * get_from_clause          - Parse back a FROM clause
 *
 * "prefix" is the keyword that denotes the start of the list of FROM
 * elements. It is FROM when used to parse back SELECT and UPDATE, but
 * is USING when parsing back DELETE.
 * ----------
 */
static void
get_from_clause(Query *query, const char *prefix, deparse_context *context)
{
    StringInfo  buf = context->buf;
    bool        first = true;
    ListCell   *l;
 
    /*
     * We use the query's jointree as a guide to what to print.  However, we
     * must ignore auto-added RTEs that are marked not inFromCl. (These can
     * only appear at the top level of the jointree, so it's sufficient to
     * check here.)  This check also ensures we ignore the rule pseudo-RTEs
     * for NEW and OLD.
     */
    foreach(l, query->jointree->fromlist)
    {
        Node       *jtnode = (Node *) lfirst(l);
 
        if (IsA(jtnode, RangeTblRef))
        {
            int         varno = ((RangeTblRef *) jtnode)->rtindex;
            RangeTblEntry *rte = rt_fetch(varno, query->rtable);
 
            if (!rte->inFromCl)
                continue;
        }
 
        if (first)
        {
            appendContextKeyword(context, prefix,
                                 -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
            first = false;
 
            get_from_clause_item(jtnode, query, context);
        }
        else
        {
            StringInfoData itembuf;
 
            appendStringInfoString(buf, ", ");
 
            /*
             * Put the new FROM item's text into itembuf so we can decide
             * after we've got it whether or not it needs to go on a new line.
             */
            initStringInfo(&itembuf);
            context->buf = &itembuf;
 
            get_from_clause_item(jtnode, query, context);
 
            /* Restore context's output buffer */
            context->buf = buf;
 
            /* Consider line-wrapping if enabled */
            if (PRETTY_INDENT(context) && context->wrapColumn >= 0)
            {
                /* Does the new item start with a new line? */
                if (itembuf.len > 0 && itembuf.data[0] == '\n')
                {
                    /* If so, we shouldn't add anything */
                    /* instead, remove any trailing spaces currently in buf */
                    removeStringInfoSpaces(buf);
                }
                else
                {
                    char       *trailing_nl;
 
                    /* Locate the start of the current line in the buffer */
                    trailing_nl = strrchr(buf->data, '\n');
                    if (trailing_nl == NULL)
                        trailing_nl = buf->data;
                    else
                        trailing_nl++;
 
                    /*
                     * Add a newline, plus some indentation, if the new item
                     * would cause an overflow.
                     */
                    if (strlen(trailing_nl) + itembuf.len > context->wrapColumn)
                        appendContextKeyword(context, "", -PRETTYINDENT_STD,
                                             PRETTYINDENT_STD,
                                             PRETTYINDENT_VAR);
                }
            }
 
            /* Add the new item */
            appendBinaryStringInfo(buf, itembuf.data, itembuf.len);
 
            /* clean up */
            pfree(itembuf.data);
        }
    }
}
 
static void
get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
{
    StringInfo  buf = context->buf;
    deparse_namespace *dpns = (deparse_namespace *) linitial(context->namespaces);
 
    if (IsA(jtnode, RangeTblRef))
    {
        int         varno = ((RangeTblRef *) jtnode)->rtindex;
        RangeTblEntry *rte = rt_fetch(varno, query->rtable);
        deparse_columns *colinfo = deparse_columns_fetch(varno, dpns);
        RangeTblFunction *rtfunc1 = NULL;
 
        if (rte->lateral)
            appendStringInfoString(buf, "LATERAL ");
 
        /* Print the FROM item proper */
        switch (rte->rtekind)
        {
            case RTE_RELATION:
                /* Normal relation RTE */
                appendStringInfo(buf, "%s%s",
                                 only_marker(rte),
                                 generate_relation_name(rte->relid,
                                                        context->namespaces));
                break;
            case RTE_SUBQUERY:
                /* Subquery RTE */
                appendStringInfoChar(buf, '(');
                get_query_def(rte->subquery, buf, context->namespaces, NULL,
                              true,
                              context->prettyFlags, context->wrapColumn,
                              context->indentLevel);
                appendStringInfoChar(buf, ')');
                break;
            case RTE_FUNCTION:
                /* Function RTE */
                rtfunc1 = (RangeTblFunction *) linitial(rte->functions);
 
                /*
                 * Omit ROWS FROM() syntax for just one function, unless it
                 * has both a coldeflist and WITH ORDINALITY. If it has both,
                 * we must use ROWS FROM() syntax to avoid ambiguity about
                 * whether the coldeflist includes the ordinality column.
                 */
                if (list_length(rte->functions) == 1 &&
                    (rtfunc1->funccolnames == NIL || !rte->funcordinality))
                {
                    get_rule_expr_funccall(rtfunc1->funcexpr, context, true);
                    /* we'll print the coldeflist below, if it has one */
                }
                else
                {
                    bool        all_unnest;
                    ListCell   *lc;
 
                    /*
                     * If all the function calls in the list are to unnest,
                     * and none need a coldeflist, then collapse the list back
                     * down to UNNEST(args).  (If we had more than one
                     * built-in unnest function, this would get more
                     * difficult.)
                     *
                     * XXX This is pretty ugly, since it makes not-terribly-
                     * future-proof assumptions about what the parser would do
                     * with the output; but the alternative is to emit our
                     * nonstandard ROWS FROM() notation for what might have
                     * been a perfectly spec-compliant multi-argument
                     * UNNEST().
                     */
                    all_unnest = true;
                    foreach(lc, rte->functions)
                    {
                        RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
 
                        if (!IsA(rtfunc->funcexpr, FuncExpr) ||
                            ((FuncExpr *) rtfunc->funcexpr)->funcid != F_UNNEST_ANYARRAY ||
                            rtfunc->funccolnames != NIL)
                        {
                            all_unnest = false;
                            break;
                        }
                    }
 
                    if (all_unnest)
                    {
                        List       *allargs = NIL;
 
                        foreach(lc, rte->functions)
                        {
                            RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
                            List       *args = ((FuncExpr *) rtfunc->funcexpr)->args;
 
                            allargs = list_concat(allargs, args);
                        }
 
                        appendStringInfoString(buf, "UNNEST(");
                        get_rule_expr((Node *) allargs, context, true);
                        appendStringInfoChar(buf, ')');
                    }
                    else
                    {
                        int         funcno = 0;
 
                        appendStringInfoString(buf, "ROWS FROM(");
                        foreach(lc, rte->functions)
                        {
                            RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
 
                            if (funcno > 0)
                                appendStringInfoString(buf, ", ");
                            get_rule_expr_funccall(rtfunc->funcexpr, context, true);
                            if (rtfunc->funccolnames != NIL)
                            {
                                /* Reconstruct the column definition list */
                                appendStringInfoString(buf, " AS ");
                                get_from_clause_coldeflist(rtfunc,
                                                           NULL,
                                                           context);
                            }
                            funcno++;
                        }
                        appendStringInfoChar(buf, ')');
                    }
                    /* prevent printing duplicate coldeflist below */
                    rtfunc1 = NULL;
                }
                if (rte->funcordinality)
                    appendStringInfoString(buf, " WITH ORDINALITY");
                break;
            case RTE_TABLEFUNC:
                get_tablefunc(rte->tablefunc, context, true);
                break;
            case RTE_VALUES:
                /* Values list RTE */
                appendStringInfoChar(buf, '(');
                get_values_def(rte->values_lists, context);
                appendStringInfoChar(buf, ')');
                break;
            case RTE_CTE:
                appendStringInfoString(buf, quote_identifier(rte->ctename));
                break;
            default:
                elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
                break;
        }
 
        /* Print the relation alias, if needed */
        get_rte_alias(rte, varno, false, context);
 
        /* Print the column definitions or aliases, if needed */
        if (rtfunc1 && rtfunc1->funccolnames != NIL)
        {
            /* Reconstruct the columndef list, which is also the aliases */
            get_from_clause_coldeflist(rtfunc1, colinfo, context);
        }
        else
        {
            /* Else print column aliases as needed */
            get_column_alias_list(colinfo, context);
        }
 
        /* Tablesample clause must go after any alias */
        if (rte->rtekind == RTE_RELATION && rte->tablesample)
            get_tablesample_def(rte->tablesample, context);
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;
        deparse_columns *colinfo = deparse_columns_fetch(j->rtindex, dpns);
        bool        need_paren_on_right;
 
        need_paren_on_right = PRETTY_PAREN(context) &&
            !IsA(j->rarg, RangeTblRef) &&
            !(IsA(j->rarg, JoinExpr) && ((JoinExpr *) j->rarg)->alias != NULL);
 
        if (!PRETTY_PAREN(context) || j->alias != NULL)
            appendStringInfoChar(buf, '(');
 
        get_from_clause_item(j->larg, query, context);
 
        switch (j->jointype)
        {
            case JOIN_INNER:
                if (j->quals)
                    appendContextKeyword(context, " JOIN ",
                                         -PRETTYINDENT_STD,
                                         PRETTYINDENT_STD,
                                         PRETTYINDENT_JOIN);
                else
                    appendContextKeyword(context, " CROSS JOIN ",
                                         -PRETTYINDENT_STD,
                                         PRETTYINDENT_STD,
                                         PRETTYINDENT_JOIN);
                break;
            case JOIN_LEFT:
                appendContextKeyword(context, " LEFT JOIN ",
                                     -PRETTYINDENT_STD,
                                     PRETTYINDENT_STD,
                                     PRETTYINDENT_JOIN);
                break;
            case JOIN_FULL:
                appendContextKeyword(context, " FULL JOIN ",
                                     -PRETTYINDENT_STD,
                                     PRETTYINDENT_STD,
                                     PRETTYINDENT_JOIN);
                break;
            case JOIN_RIGHT:
                appendContextKeyword(context, " RIGHT JOIN ",
                                     -PRETTYINDENT_STD,
                                     PRETTYINDENT_STD,
                                     PRETTYINDENT_JOIN);
                break;
            default:
                elog(ERROR, "unrecognized join type: %d",
                     (int) j->jointype);
        }
 
        if (need_paren_on_right)
            appendStringInfoChar(buf, '(');
        get_from_clause_item(j->rarg, query, context);
        if (need_paren_on_right)
            appendStringInfoChar(buf, ')');
 
        if (j->usingClause)
        {
            ListCell   *lc;
            bool        first = true;
 
            appendStringInfoString(buf, " USING (");
            /* Use the assigned names, not what's in usingClause */
            foreach(lc, colinfo->usingNames)
            {
                char       *colname = (char *) lfirst(lc);
 
                if (first)
                    first = false;
                else
                    appendStringInfoString(buf, ", ");
                appendStringInfoString(buf, quote_identifier(colname));
            }
            appendStringInfoChar(buf, ')');
 
            if (j->join_using_alias)
                appendStringInfo(buf, " AS %s",
                                 quote_identifier(j->join_using_alias->aliasname));
        }
        else if (j->quals)
        {
            appendStringInfoString(buf, " ON ");
            if (!PRETTY_PAREN(context))
                appendStringInfoChar(buf, '(');
            get_rule_expr(j->quals, context, false);
            if (!PRETTY_PAREN(context))
                appendStringInfoChar(buf, ')');
        }
        else if (j->jointype != JOIN_INNER)
        {
            /* If we didn't say CROSS JOIN above, we must provide an ON */
            appendStringInfoString(buf, " ON TRUE");
        }
 
        if (!PRETTY_PAREN(context) || j->alias != NULL)
            appendStringInfoChar(buf, ')');
 
        /* Yes, it's correct to put alias after the right paren ... */
        if (j->alias != NULL)
        {
            /*
             * Note that it's correct to emit an alias clause if and only if
             * there was one originally.  Otherwise we'd be converting a named
             * join to unnamed or vice versa, which creates semantic
             * subtleties we don't want.  However, we might print a different
             * alias name than was there originally.
             */
            appendStringInfo(buf, " %s",
                             quote_identifier(get_rtable_name(j->rtindex,
                                                              context)));
            get_column_alias_list(colinfo, context);
        }
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
}
 
/*
 * get_rte_alias - print the relation's alias, if needed
 *
 * If printed, the alias is preceded by a space, or by " AS " if use_as is true.
 */
static void
get_rte_alias(RangeTblEntry *rte, int varno, bool use_as,
              deparse_context *context)
{
    deparse_namespace *dpns = (deparse_namespace *) linitial(context->namespaces);
    char       *refname = get_rtable_name(varno, context);
    deparse_columns *colinfo = deparse_columns_fetch(varno, dpns);
    bool        printalias = false;
 
    if (rte->alias != NULL)
    {
        /* Always print alias if user provided one */
        printalias = true;
    }
    else if (colinfo->printaliases)
    {
        /* Always print alias if we need to print column aliases */
        printalias = true;
    }
    else if (rte->rtekind == RTE_RELATION)
    {
        /*
         * No need to print alias if it's same as relation name (this would
         * normally be the case, but not if set_rtable_names had to resolve a
         * conflict).
         */
        if (strcmp(refname, get_relation_name(rte->relid)) != 0)
            printalias = true;
    }
    else if (rte->rtekind == RTE_FUNCTION)
    {
        /*
         * For a function RTE, always print alias.  This covers possible
         * renaming of the function and/or instability of the FigureColname
         * rules for things that aren't simple functions.  Note we'd need to
         * force it anyway for the columndef list case.
         */
        printalias = true;
    }
    else if (rte->rtekind == RTE_SUBQUERY ||
             rte->rtekind == RTE_VALUES)
    {
        /*
         * For a subquery, always print alias.  This makes the output
         * SQL-spec-compliant, even though we allow such aliases to be omitted
         * on input.
         */
        printalias = true;
    }
    else if (rte->rtekind == RTE_CTE)
    {
        /*
         * No need to print alias if it's same as CTE name (this would
         * normally be the case, but not if set_rtable_names had to resolve a
         * conflict).
         */
        if (strcmp(refname, rte->ctename) != 0)
            printalias = true;
    }
 
    if (printalias)
        appendStringInfo(context->buf, "%s%s",
                         use_as ? " AS " : " ",
                         quote_identifier(refname));
}
 
/*
 * get_column_alias_list - print column alias list for an RTE
 *
 * Caller must already have printed the relation's alias name.
 */
static void
get_column_alias_list(deparse_columns *colinfo, deparse_context *context)
{
    StringInfo  buf = context->buf;
    int         i;
    bool        first = true;
 
    /* Don't print aliases if not needed */
    if (!colinfo->printaliases)
        return;
 
    for (i = 0; i < colinfo->num_new_cols; i++)
    {
        char       *colname = colinfo->new_colnames[i];
 
        if (first)
        {
            appendStringInfoChar(buf, '(');
            first = false;
        }
        else
            appendStringInfoString(buf, ", ");
        appendStringInfoString(buf, quote_identifier(colname));
    }
    if (!first)
        appendStringInfoChar(buf, ')');
}
 
/*
 * get_from_clause_coldeflist - reproduce FROM clause coldeflist
 *
 * When printing a top-level coldeflist (which is syntactically also the
 * relation's column alias list), use column names from colinfo.  But when
 * printing a coldeflist embedded inside ROWS FROM(), we prefer to use the
 * original coldeflist's names, which are available in rtfunc->funccolnames.
 * Pass NULL for colinfo to select the latter behavior.
 *
 * The coldeflist is appended immediately (no space) to buf.  Caller is
 * responsible for ensuring that an alias or AS is present before it.
 */
static void
get_from_clause_coldeflist(RangeTblFunction *rtfunc,
                           deparse_columns *colinfo,
                           deparse_context *context)
{
    StringInfo  buf = context->buf;
    ListCell   *l1;
    ListCell   *l2;
    ListCell   *l3;
    ListCell   *l4;
    int         i;
 
    appendStringInfoChar(buf, '(');
 
    i = 0;
    forfour(l1, rtfunc->funccoltypes,
            l2, rtfunc->funccoltypmods,
            l3, rtfunc->funccolcollations,
            l4, rtfunc->funccolnames)
    {
        Oid         atttypid = lfirst_oid(l1);
        int32       atttypmod = lfirst_int(l2);
        Oid         attcollation = lfirst_oid(l3);
        char       *attname;
 
        if (colinfo)
            attname = colinfo->colnames[i];
        else
            attname = strVal(lfirst(l4));
 
        Assert(attname);        /* shouldn't be any dropped columns here */
 
        if (i > 0)
            appendStringInfoString(buf, ", ");
        appendStringInfo(buf, "%s %s",
                         quote_identifier(attname),
                         format_type_with_typemod(atttypid, atttypmod));
        if (OidIsValid(attcollation) &&
            attcollation != get_typcollation(atttypid))
            appendStringInfo(buf, " COLLATE %s",
                             generate_collation_name(attcollation));
 
        i++;
    }
 
    appendStringInfoChar(buf, ')');
}
 
/*
 * get_tablesample_def          - print a TableSampleClause
 */
static void
get_tablesample_def(TableSampleClause *tablesample, deparse_context *context)
{
    StringInfo  buf = context->buf;
    Oid         argtypes[1];
    int         nargs;
    ListCell   *l;
 
    /*
     * We should qualify the handler's function name if it wouldn't be
     * resolved by lookup in the current search path.
     */
    argtypes[0] = INTERNALOID;
    appendStringInfo(buf, " TABLESAMPLE %s (",
                     generate_function_name(tablesample->tsmhandler, 1,
                                            NIL, argtypes,
                                            false, NULL, false));
 
    nargs = 0;
    foreach(l, tablesample->args)
    {
        if (nargs++ > 0)
            appendStringInfoString(buf, ", ");
        get_rule_expr((Node *) lfirst(l), context, false);
    }
    appendStringInfoChar(buf, ')');
 
    if (tablesample->repeatable != NULL)
    {
        appendStringInfoString(buf, " REPEATABLE (");
        get_rule_expr((Node *) tablesample->repeatable, context, false);
        appendStringInfoChar(buf, ')');
    }
}
 
/*
 * get_opclass_name         - fetch name of an index operator class
 *
 * The opclass name is appended (after a space) to buf.
 *
 * Output is suppressed if the opclass is the default for the given
 * actual_datatype.  (If you don't want this behavior, just pass
 * InvalidOid for actual_datatype.)
 */
static void
get_opclass_name(Oid opclass, Oid actual_datatype,
                 StringInfo buf)
{
    HeapTuple   ht_opc;
    Form_pg_opclass opcrec;
    char       *opcname;
    char       *nspname;
 
    ht_opc = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclass));
    if (!HeapTupleIsValid(ht_opc))
        elog(ERROR, "cache lookup failed for opclass %u", opclass);
    opcrec = (Form_pg_opclass) GETSTRUCT(ht_opc);
 
    if (!OidIsValid(actual_datatype) ||
        GetDefaultOpClass(actual_datatype, opcrec->opcmethod) != opclass)
    {
        /* Okay, we need the opclass name.  Do we need to qualify it? */
        opcname = NameStr(opcrec->opcname);
        if (OpclassIsVisible(opclass))
            appendStringInfo(buf, " %s", quote_identifier(opcname));
        else
        {
            nspname = get_namespace_name_or_temp(opcrec->opcnamespace);
            appendStringInfo(buf, " %s.%s",
                             quote_identifier(nspname),
                             quote_identifier(opcname));
        }
    }
    ReleaseSysCache(ht_opc);
}
 
/*
 * generate_opclass_name
 *      Compute the name to display for an opclass specified by OID
 *
 * The result includes all necessary quoting and schema-prefixing.
 */
char *
generate_opclass_name(Oid opclass)
{
    StringInfoData buf;
 
    initStringInfo(&buf);
    get_opclass_name(opclass, InvalidOid, &buf);
 
    return &buf.data[1];        /* get_opclass_name() prepends space */
}
 
/*
 * processIndirection - take care of array and subfield assignment
 *
 * We strip any top-level FieldStore or assignment SubscriptingRef nodes that
 * appear in the input, printing them as decoration for the base column
 * name (which we assume the caller just printed).  We might also need to
 * strip CoerceToDomain nodes, but only ones that appear above assignment
 * nodes.
 *
 * Returns the subexpression that's to be assigned.
 */
static Node *
processIndirection(Node *node, deparse_context *context)
{
    StringInfo  buf = context->buf;
    CoerceToDomain *cdomain = NULL;
 
    for (;;)
    {
        if (node == NULL)
            break;
        if (IsA(node, FieldStore))
        {
            FieldStore *fstore = (FieldStore *) node;
            Oid         typrelid;
            char       *fieldname;
 
            /* lookup tuple type */
            typrelid = get_typ_typrelid(fstore->resulttype);
            if (!OidIsValid(typrelid))
                elog(ERROR, "argument type %s of FieldStore is not a tuple type",
                     format_type_be(fstore->resulttype));
 
            /*
             * Print the field name.  There should only be one target field in
             * stored rules.  There could be more than that in executable
             * target lists, but this function cannot be used for that case.
             */
            Assert(list_length(fstore->fieldnums) == 1);
            fieldname = get_attname(typrelid,
                                    linitial_int(fstore->fieldnums), false);
            appendStringInfo(buf, ".%s", quote_identifier(fieldname));
 
            /*
             * We ignore arg since it should be an uninteresting reference to
             * the target column or subcolumn.
             */
            node = (Node *) linitial(fstore->newvals);
        }
        else if (IsA(node, SubscriptingRef))
        {
            SubscriptingRef *sbsref = (SubscriptingRef *) node;
 
            if (sbsref->refassgnexpr == NULL)
                break;
 
            printSubscripts(sbsref, context);
 
            /*
             * We ignore refexpr since it should be an uninteresting reference
             * to the target column or subcolumn.
             */
            node = (Node *) sbsref->refassgnexpr;
        }
        else if (IsA(node, CoerceToDomain))
        {
            cdomain = (CoerceToDomain *) node;
            /* If it's an explicit domain coercion, we're done */
            if (cdomain->coercionformat != COERCE_IMPLICIT_CAST)
                break;
            /* Tentatively descend past the CoerceToDomain */
            node = (Node *) cdomain->arg;
        }
        else
            break;
    }
 
    /*
     * If we descended past a CoerceToDomain whose argument turned out not to
     * be a FieldStore or array assignment, back up to the CoerceToDomain.
     * (This is not enough to be fully correct if there are nested implicit
     * CoerceToDomains, but such cases shouldn't ever occur.)
     */
    if (cdomain && node == (Node *) cdomain->arg)
        node = (Node *) cdomain;
 
    return node;
}
 
static void
printSubscripts(SubscriptingRef *sbsref, deparse_context *context)
{
    StringInfo  buf = context->buf;
    ListCell   *lowlist_item;
    ListCell   *uplist_item;
 
    lowlist_item = list_head(sbsref->reflowerindexpr);  /* could be NULL */
    foreach(uplist_item, sbsref->refupperindexpr)
    {
        appendStringInfoChar(buf, '[');
        if (lowlist_item)
        {
            /* If subexpression is NULL, get_rule_expr prints nothing */
            get_rule_expr((Node *) lfirst(lowlist_item), context, false);
            appendStringInfoChar(buf, ':');
            lowlist_item = lnext(sbsref->reflowerindexpr, lowlist_item);
        }
        /* If subexpression is NULL, get_rule_expr prints nothing */
        get_rule_expr((Node *) lfirst(uplist_item), context, false);
        appendStringInfoChar(buf, ']');
    }
}
 
/*
 * quote_identifier         - Quote an identifier only if needed
 *
 * When quotes are needed, we palloc the required space; slightly
 * space-wasteful but well worth it for notational simplicity.
 */
const char *
quote_identifier(const char *ident)
{
    /*
     * Can avoid quoting if ident starts with a lowercase letter or underscore
     * and contains only lowercase letters, digits, and underscores, *and* is
     * not any SQL keyword.  Otherwise, supply quotes.
     */
    int         nquotes = 0;
    bool        safe;
    const char *ptr;
    char       *result;
    char       *optr;
 
    /*
     * would like to use <ctype.h> macros here, but they might yield unwanted
     * locale-specific results...
     */
    safe = ((ident[0] >= 'a' && ident[0] <= 'z') || ident[0] == '_');
 
    for (ptr = ident; *ptr; ptr++)
    {
        char        ch = *ptr;
 
        if ((ch >= 'a' && ch <= 'z') ||
            (ch >= '0' && ch <= '9') ||
            (ch == '_'))
        {
            /* okay */
        }
        else
        {
            safe = false;
            if (ch == '"')
                nquotes++;
        }
    }
 
    if (quote_all_identifiers)
        safe = false;
 
    if (safe)
    {
        /*
         * Check for keyword.  We quote keywords except for unreserved ones.
         * (In some cases we could avoid quoting a col_name or type_func_name
         * keyword, but it seems much harder than it's worth to tell that.)
         *
         * Note: ScanKeywordLookup() does case-insensitive comparison, but
         * that's fine, since we already know we have all-lower-case.
         */
        int         kwnum = ScanKeywordLookup(ident, &ScanKeywords);
 
        if (kwnum >= 0 && ScanKeywordCategories[kwnum] != UNRESERVED_KEYWORD)
            safe = false;
    }
 
    if (safe)
        return ident;           /* no change needed */
 
    result = (char *) palloc(strlen(ident) + nquotes + 2 + 1);
 
    optr = result;
    *optr++ = '"';
    for (ptr = ident; *ptr; ptr++)
    {
        char        ch = *ptr;
 
        if (ch == '"')
            *optr++ = '"';
        *optr++ = ch;
    }
    *optr++ = '"';
    *optr = '\0';
 
    return result;
}
 
/*
 * quote_qualified_identifier   - Quote a possibly-qualified identifier
 *
 * Return a name of the form qualifier.ident, or just ident if qualifier
 * is NULL, quoting each component if necessary.  The result is palloc'd.
 */
char *
quote_qualified_identifier(const char *qualifier,
                           const char *ident)
{
    StringInfoData buf;
 
    initStringInfo(&buf);
    if (qualifier)
        appendStringInfo(&buf, "%s.", quote_identifier(qualifier));
    appendStringInfoString(&buf, quote_identifier(ident));
    return buf.data;
}
 
/*
 * get_relation_name
 *      Get the unqualified name of a relation specified by OID
 *
 * This differs from the underlying get_rel_name() function in that it will
 * throw error instead of silently returning NULL if the OID is bad.
 */
static char *
get_relation_name(Oid relid)
{
    char       *relname = get_rel_name(relid);
 
    if (!relname)
        elog(ERROR, "cache lookup failed for relation %u", relid);
    return relname;
}
 
/*
 * generate_relation_name
 *      Compute the name to display for a relation specified by OID
 *
 * The result includes all necessary quoting and schema-prefixing.
 *
 * If namespaces isn't NIL, it must be a list of deparse_namespace nodes.
 * We will forcibly qualify the relation name if it equals any CTE name
 * visible in the namespace list.
 */
static char *
generate_relation_name(Oid relid, List *namespaces)
{
    HeapTuple   tp;
    Form_pg_class reltup;
    bool        need_qual;
    ListCell   *nslist;
    char       *relname;
    char       *nspname;
    char       *result;
 
    tp = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tp))
        elog(ERROR, "cache lookup failed for relation %u", relid);
    reltup = (Form_pg_class) GETSTRUCT(tp);
    relname = NameStr(reltup->relname);
 
    /* Check for conflicting CTE name */
    need_qual = false;
    foreach(nslist, namespaces)
    {
        deparse_namespace *dpns = (deparse_namespace *) lfirst(nslist);
        ListCell   *ctlist;
 
        foreach(ctlist, dpns->ctes)
        {
            CommonTableExpr *cte = (CommonTableExpr *) lfirst(ctlist);
 
            if (strcmp(cte->ctename, relname) == 0)
            {
                need_qual = true;
                break;
            }
        }
        if (need_qual)
            break;
    }
 
    /* Otherwise, qualify the name if not visible in search path */
    if (!need_qual)
        need_qual = !RelationIsVisible(relid);
 
    if (need_qual)
        nspname = get_namespace_name_or_temp(reltup->relnamespace);
    else
        nspname = NULL;
 
    result = quote_qualified_identifier(nspname, relname);
 
    ReleaseSysCache(tp);
 
    return result;
}
 
/*
 * generate_qualified_relation_name
 *      Compute the name to display for a relation specified by OID
 *
 * As above, but unconditionally schema-qualify the name.
 */
static char *
generate_qualified_relation_name(Oid relid)
{
    HeapTuple   tp;
    Form_pg_class reltup;
    char       *relname;
    char       *nspname;
    char       *result;
 
    tp = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tp))
        elog(ERROR, "cache lookup failed for relation %u", relid);
    reltup = (Form_pg_class) GETSTRUCT(tp);
    relname = NameStr(reltup->relname);
 
    nspname = get_namespace_name_or_temp(reltup->relnamespace);
    if (!nspname)
        elog(ERROR, "cache lookup failed for namespace %u",
             reltup->relnamespace);
 
    result = quote_qualified_identifier(nspname, relname);
 
    ReleaseSysCache(tp);
 
    return result;
}
 
/*
 * generate_function_name
 *      Compute the name to display for a function specified by OID,
 *      given that it is being called with the specified actual arg names and
 *      types.  (Those matter because of ambiguous-function resolution rules.)
 *
 * If we're dealing with a potentially variadic function (in practice, this
 * means a FuncExpr or Aggref, not some other way of calling a function), then
 * has_variadic must specify whether variadic arguments have been merged,
 * and *use_variadic_p will be set to indicate whether to print VARIADIC in
 * the output.  For non-FuncExpr cases, has_variadic should be false and
 * use_variadic_p can be NULL.
 *
 * inGroupBy must be true if we're deparsing a GROUP BY clause.
 *
 * The result includes all necessary quoting and schema-prefixing.
 */
static char *
generate_function_name(Oid funcid, int nargs, List *argnames, Oid *argtypes,
                       bool has_variadic, bool *use_variadic_p,
                       bool inGroupBy)
{
    char       *result;
    HeapTuple   proctup;
    Form_pg_proc procform;
    char       *proname;
    bool        use_variadic;
    char       *nspname;
    FuncDetailCode p_result;
    Oid         p_funcid;
    Oid         p_rettype;
    bool        p_retset;
    int         p_nvargs;
    Oid         p_vatype;
    Oid        *p_true_typeids;
    bool        force_qualify = false;
 
    proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(proctup))
        elog(ERROR, "cache lookup failed for function %u", funcid);
    procform = (Form_pg_proc) GETSTRUCT(proctup);
    proname = NameStr(procform->proname);
 
    /*
     * Due to parser hacks to avoid needing to reserve CUBE, we need to force
     * qualification of some function names within GROUP BY.
     */
    if (inGroupBy)
    {
        if (strcmp(proname, "cube") == 0 || strcmp(proname, "rollup") == 0)
            force_qualify = true;
    }
 
    /*
     * Determine whether VARIADIC should be printed.  We must do this first
     * since it affects the lookup rules in func_get_detail().
     *
     * We always print VARIADIC if the function has a merged variadic-array
     * argument.  Note that this is always the case for functions taking a
     * VARIADIC argument type other than VARIADIC ANY.  If we omitted VARIADIC
     * and printed the array elements as separate arguments, the call could
     * match a newer non-VARIADIC function.
     */
    if (use_variadic_p)
    {
        /* Parser should not have set funcvariadic unless fn is variadic */
        Assert(!has_variadic || OidIsValid(procform->provariadic));
        use_variadic = has_variadic;
        *use_variadic_p = use_variadic;
    }
    else
    {
        Assert(!has_variadic);
        use_variadic = false;
    }
 
    /*
     * The idea here is to schema-qualify only if the parser would fail to
     * resolve the correct function given the unqualified func name with the
     * specified argtypes and VARIADIC flag.  But if we already decided to
     * force qualification, then we can skip the lookup and pretend we didn't
     * find it.
     */
    if (!force_qualify)
        p_result = func_get_detail(list_make1(makeString(proname)),
                                   NIL, argnames, nargs, argtypes,
                                   !use_variadic, true, false,
                                   &p_funcid, &p_rettype,
                                   &p_retset, &p_nvargs, &p_vatype,
                                   &p_true_typeids, NULL);
    else
    {
        p_result = FUNCDETAIL_NOTFOUND;
        p_funcid = InvalidOid;
    }
 
    if ((p_result == FUNCDETAIL_NORMAL ||
         p_result == FUNCDETAIL_AGGREGATE ||
         p_result == FUNCDETAIL_WINDOWFUNC) &&
        p_funcid == funcid)
        nspname = NULL;
    else
        nspname = get_namespace_name_or_temp(procform->pronamespace);
 
    result = quote_qualified_identifier(nspname, proname);
 
    ReleaseSysCache(proctup);
 
    return result;
}
 
/*
 * generate_operator_name
 *      Compute the name to display for an operator specified by OID,
 *      given that it is being called with the specified actual arg types.
 *      (Arg types matter because of ambiguous-operator resolution rules.
 *      Pass InvalidOid for unused arg of a unary operator.)
 *
 * The result includes all necessary quoting and schema-prefixing,
 * plus the OPERATOR() decoration needed to use a qualified operator name
 * in an expression.
 */
static char *
generate_operator_name(Oid operid, Oid arg1, Oid arg2)
{
    StringInfoData buf;
    HeapTuple   opertup;
    Form_pg_operator operform;
    char       *oprname;
    char       *nspname;
    Operator    p_result;
 
    initStringInfo(&buf);
 
    opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(operid));
    if (!HeapTupleIsValid(opertup))
        elog(ERROR, "cache lookup failed for operator %u", operid);
    operform = (Form_pg_operator) GETSTRUCT(opertup);
    oprname = NameStr(operform->oprname);
 
    /*
     * The idea here is to schema-qualify only if the parser would fail to
     * resolve the correct operator given the unqualified op name with the
     * specified argtypes.
     */
    switch (operform->oprkind)
    {
        case 'b':
            p_result = oper(NULL, list_make1(makeString(oprname)), arg1, arg2,
                            true, -1);
            break;
        case 'l':
            p_result = left_oper(NULL, list_make1(makeString(oprname)), arg2,
                                 true, -1);
            break;
        default:
            elog(ERROR, "unrecognized oprkind: %d", operform->oprkind);
            p_result = NULL;    /* keep compiler quiet */
            break;
    }
 
    if (p_result != NULL && oprid(p_result) == operid)
        nspname = NULL;
    else
    {
        nspname = get_namespace_name_or_temp(operform->oprnamespace);
        appendStringInfo(&buf, "OPERATOR(%s.", quote_identifier(nspname));
    }
 
    appendStringInfoString(&buf, oprname);
 
    if (nspname)
        appendStringInfoChar(&buf, ')');
 
    if (p_result != NULL)
        ReleaseSysCache(p_result);
 
    ReleaseSysCache(opertup);
 
    return buf.data;
}
 
/*
 * generate_operator_clause --- generate a binary-operator WHERE clause
 *
 * This is used for internally-generated-and-executed SQL queries, where
 * precision is essential and readability is secondary.  The basic
 * requirement is to append "leftop op rightop" to buf, where leftop and
 * rightop are given as strings and are assumed to yield types leftoptype
 * and rightoptype; the operator is identified by OID.  The complexity
 * comes from needing to be sure that the parser will select the desired
 * operator when the query is parsed.  We always name the operator using
 * OPERATOR(schema.op) syntax, so as to avoid search-path uncertainties.
 * We have to emit casts too, if either input isn't already the input type
 * of the operator; else we are at the mercy of the parser's heuristics for
 * ambiguous-operator resolution.  The caller must ensure that leftop and
 * rightop are suitable arguments for a cast operation; it's best to insert
 * parentheses if they aren't just variables or parameters.
 */
void
generate_operator_clause(StringInfo buf,
                         const char *leftop, Oid leftoptype,
                         Oid opoid,
                         const char *rightop, Oid rightoptype)
{
    HeapTuple   opertup;
    Form_pg_operator operform;
    char       *oprname;
    char       *nspname;
 
    opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(opoid));
    if (!HeapTupleIsValid(opertup))
        elog(ERROR, "cache lookup failed for operator %u", opoid);
    operform = (Form_pg_operator) GETSTRUCT(opertup);
    Assert(operform->oprkind == 'b');
    oprname = NameStr(operform->oprname);
 
    nspname = get_namespace_name(operform->oprnamespace);
 
    appendStringInfoString(buf, leftop);
    if (leftoptype != operform->oprleft)
        add_cast_to(buf, operform->oprleft);
    appendStringInfo(buf, " OPERATOR(%s.", quote_identifier(nspname));
    appendStringInfoString(buf, oprname);
    appendStringInfo(buf, ") %s", rightop);
    if (rightoptype != operform->oprright)
        add_cast_to(buf, operform->oprright);
 
    ReleaseSysCache(opertup);
}
 
/*
 * Add a cast specification to buf.  We spell out the type name the hard way,
 * intentionally not using format_type_be().  This is to avoid corner cases
 * for CHARACTER, BIT, and perhaps other types, where specifying the type
 * using SQL-standard syntax results in undesirable data truncation.  By
 * doing it this way we can be certain that the cast will have default (-1)
 * target typmod.
 */
static void
add_cast_to(StringInfo buf, Oid typid)
{
    HeapTuple   typetup;
    Form_pg_type typform;
    char       *typname;
    char       *nspname;
 
    typetup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
    if (!HeapTupleIsValid(typetup))
        elog(ERROR, "cache lookup failed for type %u", typid);
    typform = (Form_pg_type) GETSTRUCT(typetup);
 
    typname = NameStr(typform->typname);
    nspname = get_namespace_name_or_temp(typform->typnamespace);
 
    appendStringInfo(buf, "::%s.%s",
                     quote_identifier(nspname), quote_identifier(typname));
 
    ReleaseSysCache(typetup);
}
 
/*
 * generate_qualified_type_name
 *      Compute the name to display for a type specified by OID
 *
 * This is different from format_type_be() in that we unconditionally
 * schema-qualify the name.  That also means no special syntax for
 * SQL-standard type names ... although in current usage, this should
 * only get used for domains, so such cases wouldn't occur anyway.
 */
static char *
generate_qualified_type_name(Oid typid)
{
    HeapTuple   tp;
    Form_pg_type typtup;
    char       *typname;
    char       *nspname;
    char       *result;
 
    tp = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
    if (!HeapTupleIsValid(tp))
        elog(ERROR, "cache lookup failed for type %u", typid);
    typtup = (Form_pg_type) GETSTRUCT(tp);
    typname = NameStr(typtup->typname);
 
    nspname = get_namespace_name_or_temp(typtup->typnamespace);
    if (!nspname)
        elog(ERROR, "cache lookup failed for namespace %u",
             typtup->typnamespace);
 
    result = quote_qualified_identifier(nspname, typname);
 
    ReleaseSysCache(tp);
 
    return result;
}
 
/*
 * generate_collation_name
 *      Compute the name to display for a collation specified by OID
 *
 * The result includes all necessary quoting and schema-prefixing.
 */
char *
generate_collation_name(Oid collid)
{
    HeapTuple   tp;
    Form_pg_collation colltup;
    char       *collname;
    char       *nspname;
    char       *result;
 
    tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
    if (!HeapTupleIsValid(tp))
        elog(ERROR, "cache lookup failed for collation %u", collid);
    colltup = (Form_pg_collation) GETSTRUCT(tp);
    collname = NameStr(colltup->collname);
 
    if (!CollationIsVisible(collid))
        nspname = get_namespace_name_or_temp(colltup->collnamespace);
    else
        nspname = NULL;
 
    result = quote_qualified_identifier(nspname, collname);
 
    ReleaseSysCache(tp);
 
    return result;
}
 
/*
 * Given a C string, produce a TEXT datum.
 *
 * We assume that the input was palloc'd and may be freed.
 */
static text *
string_to_text(char *str)
{
    text       *result;
 
    result = cstring_to_text(str);
    pfree(str);
    return result;
}
 
/*
 * Generate a C string representing a relation options from text[] datum.
 */
static void
get_reloptions(StringInfo buf, Datum reloptions)
{
    Datum      *options;
    int         noptions;
    int         i;
 
    deconstruct_array_builtin(DatumGetArrayTypeP(reloptions), TEXTOID,
                              &options, NULL, &noptions);
 
    for (i = 0; i < noptions; i++)
    {
        char       *option = TextDatumGetCString(options[i]);
        char       *name;
        char       *separator;
        char       *value;
 
        /*
         * Each array element should have the form name=value.  If the "=" is
         * missing for some reason, treat it like an empty value.
         */
        name = option;
        separator = strchr(option, '=');
        if (separator)
        {
            *separator = '\0';
            value = separator + 1;
        }
        else
            value = "";
 
        if (i > 0)
            appendStringInfoString(buf, ", ");
        appendStringInfo(buf, "%s=", quote_identifier(name));
 
        /*
         * In general we need to quote the value; but to avoid unnecessary
         * clutter, do not quote if it is an identifier that would not need
         * quoting.  (We could also allow numbers, but that is a bit trickier
         * than it looks --- for example, are leading zeroes significant?  We
         * don't want to assume very much here about what custom reloptions
         * might mean.)
         */
        if (quote_identifier(value) == value)
            appendStringInfoString(buf, value);
        else
            simple_quote_literal(buf, value);
 
        pfree(option);
    }
}
 
/*
 * Generate a C string representing a relation's reloptions, or NULL if none.
 */
static char *
flatten_reloptions(Oid relid)
{
    char       *result = NULL;
    HeapTuple   tuple;
    Datum       reloptions;
    bool        isnull;
 
    tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for relation %u", relid);
 
    reloptions = SysCacheGetAttr(RELOID, tuple,
                                 Anum_pg_class_reloptions, &isnull);
    if (!isnull)
    {
        StringInfoData buf;
 
        initStringInfo(&buf);
        get_reloptions(&buf, reloptions);
 
        result = buf.data;
    }
 
    ReleaseSysCache(tuple);
 
    return result;
}
 
/*
 * get_range_partbound_string
 *      A C string representation of one range partition bound
 */
char *
get_range_partbound_string(List *bound_datums)
{
    deparse_context context;
    StringInfo  buf = makeStringInfo();
    ListCell   *cell;
    char       *sep;
 
    memset(&context, 0, sizeof(deparse_context));
    context.buf = buf;
 
    appendStringInfoChar(buf, '(');
    sep = "";
    foreach(cell, bound_datums)
    {
        PartitionRangeDatum *datum =
            lfirst_node(PartitionRangeDatum, cell);
 
        appendStringInfoString(buf, sep);
        if (datum->kind == PARTITION_RANGE_DATUM_MINVALUE)
            appendStringInfoString(buf, "MINVALUE");
        else if (datum->kind == PARTITION_RANGE_DATUM_MAXVALUE)
            appendStringInfoString(buf, "MAXVALUE");
        else
        {
            Const      *val = castNode(Const, datum->value);
 
            get_const_expr(val, &context, -1);
        }
        sep = ", ";
    }
    appendStringInfoChar(buf, ')');
 
    return buf->data;
}