path: root/src/backend/utils/adt/ruleutils.c

/*-------------------------------------------------------------------------
 *
 * ruleutils.c
 *	  Functions to convert stored expressions/querytrees back to
 *	  source text
 *
 * Portions Copyright (c) 1996-2019, 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/sysattr.h"
#include "access/table.h"
#include "catalog/dependency.h"
#include "catalog/indexing.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 "optimizer/optimizer.h"
#include "parser/parse_node.h"
#include "parser/parse_agg.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.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

/* 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 */
	List	   *windowClause;	/* Current query level's WINDOW clause */
	List	   *windowTList;	/* targetlist for resolving 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 prettyprint */
	bool		varprefix;		/* true to print prefixes on Vars */
	ParseExprKind special_exprkind; /* set only for exprkinds needing special
									 * handling */
} 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.
 *
 * The rangetable is the list of actual RTEs from the query tree, and the
 * cte list is the list of actual CTEs.
 *
 * 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.
 *
 * 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 PlanState node that is the immediate
 * parent of the expression to be deparsed, as well as a list of that
 * PlanState's ancestors.  In addition, we store its outer and inner subplan
 * state nodes, as well as their plan nodes' 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 PlanState, 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	   *ctes;			/* List of CommonTableExpr nodes */
	/* 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: */
	PlanState  *planstate;		/* immediate parent of current expression */
	List	   *ancestors;		/* ancestors of planstate */
	PlanState  *outer_planstate;	/* outer subplan state, or NULL if none */
	PlanState  *inner_planstate;	/* inner subplan state, 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 */
} 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.
 */
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.
	 * Also, if the column has been dropped, both are zero.
	 *
	 * 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 */
} 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;


/* ----------
 * Global data
 * ----------
 */
static SPIPlanPtr plan_getrulebyoid = NULL;
static const char *query_getrulebyoid = "SELECT * FROM pg_catalog.pg_rewrite WHERE oid = $1";
static SPIPlanPtr plan_getviewrule = NULL;
static const char *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,
							 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 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, const char *relname,
				   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 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 identify_join_columns(JoinExpr *j, RangeTblEntry *jrte,
					  deparse_columns *colinfo);
static void flatten_join_using_qual(Node *qual,
						List **leftvars, List **rightvars);
static char *get_rtable_name(int rtindex, deparse_context *context);
static void set_deparse_planstate(deparse_namespace *dpns, PlanState *ps);
static void push_child_plan(deparse_namespace *dpns, PlanState *ps,
				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,
			  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,
					 TupleDesc resultDesc);
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_utility_query_def(Query *query, deparse_context *context);
static void get_basic_select_query(Query *query, deparse_context *context,
					   TupleDesc resultDesc);
static void get_target_list(List *targetList, deparse_context *context,
				TupleDesc resultDesc);
static void get_setop_query(Node *setOp, Query *query,
				deparse_context *context,
				TupleDesc resultDesc);
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 char *get_variable(Var *var, int levelsup, bool istoplevel,
			 deparse_context *context);
static void get_special_variable(Node *node, deparse_context *context,
					 void *private);
static void resolve_special_varno(Node *node, deparse_context *context,
					  void *private,
					  void (*callback) (Node *, deparse_context *, void *));
static Node *find_param_referent(Param *param, deparse_context *context,
					deparse_namespace **dpns_p, ListCell **ancestor_cell_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_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_combine_expr(Node *node, deparse_context *context,
					 void *private);
static void get_windowfunc_expr(WindowFunc *wfunc, 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 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_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,
					   ParseExprKind special_exprkind);
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);

#define only_marker(rte)  ((rte)->inh ? "" : "ONLY ")


/* ----------
 * 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 = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;

	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
	 */
	if (SPI_connect() != SPI_OK_CONNECT)
		elog(ERROR, "SPI_connect failed");

	/*
	 * 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;
}


/* ----------
 * 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 = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : 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_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 = PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA;

	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 = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : 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));
}

/*
 * 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
	 */
	if (SPI_connect() != SPI_OK_CONNECT)
		elog(ERROR, "SPI_connect failed");

	/*
	 * 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;
}

/* ----------
 * 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;
	Oid			argtypes[1];	/* dummy */
	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.ctes = NIL;
		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.windowClause = NIL;
		context.windowTList = NIL;
		context.varprefix = true;
		context.prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
		context.wrapColumn = WRAP_COLUMN_DEFAULT;
		context.indentLevel = PRETTYINDENT_STD;
		context.special_exprkind = EXPR_KIND_NONE;

		get_rule_expr(qual, &context, false);

		appendStringInfoString(&buf, ") ");
	}

	appendStringInfo(&buf, "EXECUTE FUNCTION %s(",
					 generate_function_name(trigrec->tgfoid, 0,
											NIL, argtypes,
											false, NULL, EXPR_KIND_NONE));

	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;
}

/* ----------
 * 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 = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;

	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 = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;

	return pg_get_indexdef_worker(indexrelid, 0, NULL,
								  true, true,
								  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;
	bool		isnull;
	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 = SysCacheGetAttr(INDEXRELID, ht_idx,
								   Anum_pg_index_indcollation, &isnull);
	Assert(!isnull);
	indcollation = (oidvector *) DatumGetPointer(indcollDatum);

	indclassDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
									Anum_pg_index_indclass, &isnull);
	Assert(!isnull);
	indclass = (oidvector *) DatumGetPointer(indclassDatum);

	indoptionDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
									 Anum_pg_index_indoption, &isnull);
	Assert(!isnull);
	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;
		bool		isnull;
		char	   *exprsString;

		exprsDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
									 Anum_pg_index_indexprs, &isnull);
		Assert(!isnull);
		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];
		int16		opt = indoption->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(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))
		{
			Oid			indcoll;

			/* Add collation, if not default for column */
			indcoll = indcollation->values[keyno];
			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], keycoltype, &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 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))
				tblspc = MyDatabaseTableSpace;
			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;
			bool		isnull;
			char	   *predString;

			/* Convert text string to node tree */
			predDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
										Anum_pg_index_indpred, &isnull);
			Assert(!isnull);
			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_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, 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 missing_ok)
{
	Form_pg_statistic_ext statextrec;
	HeapTuple	statexttup;
	StringInfoData buf;
	int			colno;
	char	   *nsp;
	ArrayType  *arr;
	char	   *enabled;
	Datum		datum;
	bool		isnull;
	bool		ndistinct_enabled;
	bool		dependencies_enabled;
	int			i;

	statexttup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(statextid));

	if (!HeapTupleIsValid(statexttup))
	{
		if (missing_ok)
			return NULL;
		elog(ERROR, "cache lookup failed for statistics object %u", statextid);
	}

	statextrec = (Form_pg_statistic_ext) GETSTRUCT(statexttup);

	initStringInfo(&buf);

	nsp = get_namespace_name(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 = SysCacheGetAttr(STATEXTOID, statexttup,
							Anum_pg_statistic_ext_stxkind, &isnull);
	Assert(!isnull);
	arr = DatumGetArrayTypeP(datum);
	if (ARR_NDIM(arr) != 1 ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != CHAROID)
		elog(ERROR, "stxkind is not a 1-D char array");
	enabled = (char *) ARR_DATA_PTR(arr);

	ndistinct_enabled = false;
	dependencies_enabled = false;

	for (i = 0; i < ARR_DIMS(arr)[0]; i++)
	{
		if (enabled[i] == STATS_EXT_NDISTINCT)
			ndistinct_enabled = true;
		if (enabled[i] == STATS_EXT_DEPENDENCIES)
			dependencies_enabled = true;
	}

	/*
	 * 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.
	 */
	if (!ndistinct_enabled || !dependencies_enabled)
	{
		appendStringInfoString(&buf, " (");
		if (ndistinct_enabled)
			appendStringInfoString(&buf, "ndistinct");
		else if (dependencies_enabled)
			appendStringInfoString(&buf, "dependencies");
		appendStringInfoChar(&buf, ')');
	}

	appendStringInfoString(&buf, " ON ");

	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));
	}

	appendStringInfo(&buf, " FROM %s",
					 generate_relation_name(statextrec->stxrelid, NIL));

	ReleaseSysCache(statexttup);

	return buf.data;
}

/*
 * pg_get_partkeydef
 *
 * Returns the partition key specification, ie, the following:
 *
 * PARTITION BY { 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 = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;

	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;
	bool		isnull;
	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 = SysCacheGetAttr(PARTRELID, tuple,
							Anum_pg_partitioned_table_partclass, &isnull);
	Assert(!isnull);
	partclass = (oidvector *) DatumGetPointer(datum);

	datum = SysCacheGetAttr(PARTRELID, tuple,
							Anum_pg_partitioned_table_partcollation, &isnull);
	Assert(!isnull);
	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;
		bool		isnull;
		char	   *exprsString;

		exprsDatum = SysCacheGetAttr(PARTRELID, tuple,
									 Anum_pg_partitioned_table_partexprs, &isnull);
		Assert(!isnull);
		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)
				appendStringInfo(&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(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_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 = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : 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));
}

/*
 * 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 = SysCacheGetAttr(CONSTROID, tup,
									  Anum_pg_constraint_conkey, &isnull);
				if (isnull)
					elog(ERROR, "null conkey for constraint %u",
						 constraintId);

				decompile_column_index_array(val, conForm->conrelid, &buf);

				/* add foreign relation name */
				appendStringInfo(&buf, ") REFERENCES %s(",
								 generate_relation_name(conForm->confrelid,
														NIL));

				/* Fetch and build referenced-column list */
				val = SysCacheGetAttr(CONSTROID, tup,
									  Anum_pg_constraint_confkey, &isnull);
				if (isnull)
					elog(ERROR, "null confkey for constraint %u",
						 constraintId);

				decompile_column_index_array(val, conForm->confrelid, &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);

				break;
			}
		case CONSTRAINT_PRIMARY:
		case CONSTRAINT_UNIQUE:
			{
				Datum		val;
				bool		isnull;
				Oid			indexId;
				int			keyatts;
				HeapTuple	indtup;

				/* Start off the constraint definition */
				if (conForm->contype == CONSTRAINT_PRIMARY)
					appendStringInfoString(&buf, "PRIMARY KEY (");
				else
					appendStringInfoString(&buf, "UNIQUE (");

				/* Fetch and build target column list */
				val = SysCacheGetAttr(CONSTROID, tup,
									  Anum_pg_constraint_conkey, &isnull);
				if (isnull)
					elog(ERROR, "null conkey for constraint %u",
						 constraintId);

				keyatts = decompile_column_index_array(val, conForm->conrelid, &buf);

				appendStringInfoChar(&buf, ')');

				indexId = get_constraint_index(constraintId);

				/* Build including column list (from pg_index.indkeys) */
				indtup = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexId));
				if (!HeapTupleIsValid(indtup))
					elog(ERROR, "cache lookup failed for index %u", indexId);
				val = SysCacheGetAttr(INDEXRELID, indtup,
									  Anum_pg_index_indnatts, &isnull);
				if (isnull)
					elog(ERROR, "null indnatts for index %u", indexId);
				if (DatumGetInt32(val) > keyatts)
				{
					Datum		cols;
					Datum	   *keys;
					int			nKeys;
					int			j;

					appendStringInfoString(&buf, " INCLUDE (");

					cols = SysCacheGetAttr(INDEXRELID, indtup,
										   Anum_pg_index_indkey, &isnull);
					if (isnull)
						elog(ERROR, "null indkey for index %u", indexId);

					deconstruct_array(DatumGetArrayTypeP(cols),
									  INT2OID, 2, true, 's',
									  &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);
					}

					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;
				bool		isnull;
				char	   *conbin;
				char	   *consrc;
				Node	   *expr;
				List	   *context;

				/* Fetch constraint expression in parsetree form */
				val = SysCacheGetAttr(CONSTROID, tup,
									  Anum_pg_constraint_conbin, &isnull);
				if (isnull)
					elog(ERROR, "null conbin for constraint %u",
						 constraintId);

				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_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;
				bool		isnull;
				Datum	   *elems;
				int			nElems;
				int			i;
				Oid		   *operators;

				/* Extract operator OIDs from the pg_constraint tuple */
				val = SysCacheGetAttr(CONSTROID, tup,
									  Anum_pg_constraint_conexclop,
									  &isnull);
				if (isnull)
					elog(ERROR, "null conexclop for constraint %u",
						 constraintId);

				deconstruct_array(DatumGetArrayTypeP(val),
								  OIDOID, sizeof(Oid), true, 'i',
								  &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");
	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,
							 StringInfo buf)
{
	Datum	   *keys;
	int			nKeys;
	int			j;

	/* Extract data from array of int16 */
	deconstruct_array(DatumGetArrayTypeP(column_index_array),
					  INT2OID, 2, true, 's',
					  &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", quote_identifier(colName));
	}

	return nKeys;
}


/* ----------
 * 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,