• Tom Lane's avatar
    Release any detoasted copies of arrays that are made temporarily in · 353a1cca
    Tom Lane authored
    ri_FetchConstraintInfo, to avoid a query-duration memory leak when that
    routine is called by RI_FKey_keyequal_upd_fk (which isn't executed in a
    short-lived context).  This problem was latent when the routine was added
    in February, but it didn't become serious until the varvarlena patch made
    it quite likely that the fields being examined would be "toasted" (ie, have
    short headers).  Per report from Stephen Denne.
    353a1cca
ri_triggers.c 104 KB
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/* ----------
 * ri_triggers.c
 *
 *	Generic trigger procedures for referential integrity constraint
 *	checks.
 *
 *	Note about memory management: the private hashtables kept here live
 *	across query and transaction boundaries, in fact they live as long as
 *	the backend does.  This works because the hashtable structures
 *	themselves are allocated by dynahash.c in its permanent DynaHashCxt,
 *	and the SPI plans they point to are saved using SPI_saveplan().
 *	There is not currently any provision for throwing away a no-longer-needed
 *	plan --- consider improving this someday.
 *
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 *
 * $PostgreSQL: pgsql/src/backend/utils/adt/ri_triggers.c,v 1.102 2008/01/25 04:46:07 tgl Exp $
 *
 * ----------
 */


/* ----------
 * Internal TODO:
 *
 *		Add MATCH PARTIAL logic.
 * ----------
 */

#include "postgres.h"

#include "catalog/pg_constraint.h"
#include "catalog/pg_operator.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "miscadmin.h"
#include "utils/acl.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"


/* ----------
 * Local definitions
 * ----------
 */

#define RI_MAX_NUMKEYS					INDEX_MAX_KEYS

#define RI_INIT_QUERYHASHSIZE			128

#define RI_KEYS_ALL_NULL				0
#define RI_KEYS_SOME_NULL				1
#define RI_KEYS_NONE_NULL				2

/* queryno values must be distinct for the convenience of ri_PerformCheck */
#define RI_PLAN_CHECK_LOOKUPPK_NOCOLS	1
#define RI_PLAN_CHECK_LOOKUPPK			2
#define RI_PLAN_CASCADE_DEL_DODELETE	3
#define RI_PLAN_CASCADE_UPD_DOUPDATE	4
#define RI_PLAN_NOACTION_DEL_CHECKREF	5
#define RI_PLAN_NOACTION_UPD_CHECKREF	6
#define RI_PLAN_RESTRICT_DEL_CHECKREF	7
#define RI_PLAN_RESTRICT_UPD_CHECKREF	8
#define RI_PLAN_SETNULL_DEL_DOUPDATE	9
#define RI_PLAN_SETNULL_UPD_DOUPDATE	10
#define RI_PLAN_KEYEQUAL_UPD			11

#define MAX_QUOTED_NAME_LEN  (NAMEDATALEN*2+3)
#define MAX_QUOTED_REL_NAME_LEN  (MAX_QUOTED_NAME_LEN*2)

#define RIAttName(rel, attnum)	NameStr(*attnumAttName(rel, attnum))
#define RIAttType(rel, attnum)	SPI_gettypeid(RelationGetDescr(rel), attnum)

#define RI_TRIGTYPE_INSERT 1
#define RI_TRIGTYPE_UPDATE 2
#define RI_TRIGTYPE_INUP   3
#define RI_TRIGTYPE_DELETE 4

#define RI_KEYPAIR_FK_IDX	0
#define RI_KEYPAIR_PK_IDX	1


/* ----------
 * RI_ConstraintInfo
 *
 *	Information extracted from an FK pg_constraint entry.
 * ----------
 */
typedef struct RI_ConstraintInfo
{
	Oid			constraint_id;	/* OID of pg_constraint entry */
	NameData	conname;		/* name of the FK constraint */
	Oid			pk_relid;		/* referenced relation */
	Oid			fk_relid;		/* referencing relation */
	char		confupdtype;	/* foreign key's ON UPDATE action */
	char		confdeltype;	/* foreign key's ON DELETE action */
	char		confmatchtype;	/* foreign key's match type */
	int			nkeys;			/* number of key columns */
	int16		pk_attnums[RI_MAX_NUMKEYS];		/* attnums of referenced cols */
	int16		fk_attnums[RI_MAX_NUMKEYS];		/* attnums of referencing cols */
	Oid			pf_eq_oprs[RI_MAX_NUMKEYS];		/* equality operators (PK =
												 * FK) */
	Oid			pp_eq_oprs[RI_MAX_NUMKEYS];		/* equality operators (PK =
												 * PK) */
	Oid			ff_eq_oprs[RI_MAX_NUMKEYS];		/* equality operators (FK =
												 * FK) */
} RI_ConstraintInfo;


/* ----------
 * RI_QueryKey
 *
 *	The key identifying a prepared SPI plan in our query hashtable
 * ----------
 */
typedef struct RI_QueryKey
{
	char		constr_type;
	Oid			constr_id;
	int32		constr_queryno;
	Oid			fk_relid;
	Oid			pk_relid;
	int32		nkeypairs;
	int16		keypair[RI_MAX_NUMKEYS][2];
} RI_QueryKey;


/* ----------
 * RI_QueryHashEntry
 * ----------
 */
typedef struct RI_QueryHashEntry
{
	RI_QueryKey key;
	SPIPlanPtr	plan;
} RI_QueryHashEntry;


/* ----------
 * RI_CompareKey
 *
 *	The key identifying an entry showing how to compare two values
 * ----------
 */
typedef struct RI_CompareKey
{
	Oid			eq_opr;			/* the equality operator to apply */
	Oid			typeid;			/* the data type to apply it to */
} RI_CompareKey;


/* ----------
 * RI_CompareHashEntry
 * ----------
 */
typedef struct RI_CompareHashEntry
{
	RI_CompareKey key;
	bool		valid;			/* successfully initialized? */
	FmgrInfo	eq_opr_finfo;	/* call info for equality fn */
	FmgrInfo	cast_func_finfo;	/* in case we must coerce input */
} RI_CompareHashEntry;


/* ----------
 * Local data
 * ----------
 */
static HTAB *ri_query_cache = NULL;
static HTAB *ri_compare_cache = NULL;


/* ----------
 * Local function prototypes
 * ----------
 */
static void quoteOneName(char *buffer, const char *name);
static void quoteRelationName(char *buffer, Relation rel);
static void ri_GenerateQual(StringInfo buf,
				const char *sep,
				const char *leftop, Oid leftoptype,
				Oid opoid,
				const char *rightop, Oid rightoptype);
static int ri_NullCheck(Relation rel, HeapTuple tup,
			 RI_QueryKey *key, int pairidx);
static void ri_BuildQueryKeyFull(RI_QueryKey *key,
					 const RI_ConstraintInfo *riinfo,
					 int32 constr_queryno);
static void ri_BuildQueryKeyPkCheck(RI_QueryKey *key,
						const RI_ConstraintInfo *riinfo,
						int32 constr_queryno);
static bool ri_KeysEqual(Relation rel, HeapTuple oldtup, HeapTuple newtup,
			 const RI_ConstraintInfo *riinfo, bool rel_is_pk);
static bool ri_AllKeysUnequal(Relation rel, HeapTuple oldtup, HeapTuple newtup,
				  const RI_ConstraintInfo *riinfo, bool rel_is_pk);
static bool ri_OneKeyEqual(Relation rel, int column,
			   HeapTuple oldtup, HeapTuple newtup,
			   const RI_ConstraintInfo *riinfo, bool rel_is_pk);
static bool ri_AttributesEqual(Oid eq_opr, Oid typeid,
				   Datum oldvalue, Datum newvalue);
static bool ri_Check_Pk_Match(Relation pk_rel, Relation fk_rel,
				  HeapTuple old_row,
				  const RI_ConstraintInfo *riinfo);

static void ri_InitHashTables(void);
static SPIPlanPtr ri_FetchPreparedPlan(RI_QueryKey *key);
static void ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan);
static RI_CompareHashEntry *ri_HashCompareOp(Oid eq_opr, Oid typeid);

static void ri_CheckTrigger(FunctionCallInfo fcinfo, const char *funcname,
				int tgkind);
static void ri_FetchConstraintInfo(RI_ConstraintInfo *riinfo,
					   Trigger *trigger, Relation trig_rel, bool rel_is_pk);
static SPIPlanPtr ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
			 RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel,
			 bool cache_plan);
static bool ri_PerformCheck(RI_QueryKey *qkey, SPIPlanPtr qplan,
				Relation fk_rel, Relation pk_rel,
				HeapTuple old_tuple, HeapTuple new_tuple,
				bool detectNewRows,
				int expect_OK, const char *constrname);
static void ri_ExtractValues(RI_QueryKey *qkey, int key_idx,
				 Relation rel, HeapTuple tuple,
				 Datum *vals, char *nulls);
static void ri_ReportViolation(RI_QueryKey *qkey, const char *constrname,
				   Relation pk_rel, Relation fk_rel,
				   HeapTuple violator, TupleDesc tupdesc,
				   bool spi_err);


/* ----------
 * RI_FKey_check -
 *
 *	Check foreign key existence (combined for INSERT and UPDATE).
 * ----------
 */
static Datum
RI_FKey_check(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	new_row;
	HeapTuple	old_row;
	Buffer		new_row_buf;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_check", RI_TRIGTYPE_INUP);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						 trigdata->tg_trigger, trigdata->tg_relation, false);

	if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
	{
		old_row = trigdata->tg_trigtuple;
		new_row = trigdata->tg_newtuple;
		new_row_buf = trigdata->tg_newtuplebuf;
	}
	else
	{
		old_row = NULL;
		new_row = trigdata->tg_trigtuple;
		new_row_buf = trigdata->tg_trigtuplebuf;
	}

	/*
	 * We should not even consider checking the row if it is no longer valid,
	 * since it was either deleted (so the deferred check should be skipped)
	 * or updated (in which case only the latest version of the row should be
	 * checked).  Test its liveness according to SnapshotSelf.
	 *
	 * NOTE: The normal coding rule is that one must acquire the buffer
	 * content lock to call HeapTupleSatisfiesVisibility.  We can skip that
	 * here because we know that AfterTriggerExecute just fetched the tuple
	 * successfully, so there cannot be a VACUUM compaction in progress on the
	 * page (either heap_fetch would have waited for the VACUUM, or the
	 * VACUUM's LockBufferForCleanup would be waiting for us to drop pin). And
	 * since this is a row inserted by our open transaction, no one else can
	 * be entitled to change its xmin/xmax.
	 */
	Assert(new_row_buf != InvalidBuffer);
	if (!HeapTupleSatisfiesVisibility(new_row, SnapshotSelf, new_row_buf))
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables.
	 *
	 * pk_rel is opened in RowShareLock mode since that's what our eventual
	 * SELECT FOR SHARE will get on it.
	 */
	fk_rel = trigdata->tg_relation;
	pk_rel = heap_open(riinfo.pk_relid, RowShareLock);

	/* ----------
	 * SQL3 11.9 <referential constraint definition>
	 *	General rules 2) a):
	 *		If Rf and Rt are empty (no columns to compare given)
	 *		constraint is true if 0 < (SELECT COUNT(*) FROM T)
	 *
	 *	Note: The special case that no columns are given cannot
	 *		occur up to now in Postgres, it's just there for
	 *		future enhancements.
	 * ----------
	 */
	if (riinfo.nkeys == 0)
	{
		ri_BuildQueryKeyFull(&qkey, &riinfo, RI_PLAN_CHECK_LOOKUPPK_NOCOLS);

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

		if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
		{
			char		querystr[MAX_QUOTED_REL_NAME_LEN + 100];
			char		pkrelname[MAX_QUOTED_REL_NAME_LEN];

			/* ---------
			 * The query string built is
			 *	SELECT 1 FROM ONLY <pktable>
			 * ----------
			 */
			quoteRelationName(pkrelname, pk_rel);
			snprintf(querystr, sizeof(querystr),
					 "SELECT 1 FROM ONLY %s x FOR SHARE OF x",
					 pkrelname);

			/* Prepare and save the plan */
			qplan = ri_PlanCheck(querystr, 0, NULL,
								 &qkey, fk_rel, pk_rel, true);
		}

		/*
		 * Execute the plan
		 */
		ri_PerformCheck(&qkey, qplan,
						fk_rel, pk_rel,
						NULL, NULL,
						false,
						SPI_OK_SELECT,
						NameStr(riinfo.conname));

		if (SPI_finish() != SPI_OK_FINISH)
			elog(ERROR, "SPI_finish failed");

		heap_close(pk_rel, RowShareLock);

		return PointerGetDatum(NULL);
	}

	if (riinfo.confmatchtype == FKCONSTR_MATCH_PARTIAL)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("MATCH PARTIAL not yet implemented")));

	ri_BuildQueryKeyFull(&qkey, &riinfo, RI_PLAN_CHECK_LOOKUPPK);

	switch (ri_NullCheck(fk_rel, new_row, &qkey, RI_KEYPAIR_FK_IDX))
	{
		case RI_KEYS_ALL_NULL:

			/*
			 * No check - if NULLs are allowed at all is already checked by
			 * NOT NULL constraint.
			 *
			 * This is true for MATCH FULL, MATCH PARTIAL, and MATCH
			 * <unspecified>
			 */
			heap_close(pk_rel, RowShareLock);
			return PointerGetDatum(NULL);

		case RI_KEYS_SOME_NULL:

			/*
			 * This is the only case that differs between the three kinds of
			 * MATCH.
			 */
			switch (riinfo.confmatchtype)
			{
				case FKCONSTR_MATCH_FULL:

					/*
					 * Not allowed - MATCH FULL says either all or none of the
					 * attributes can be NULLs
					 */
					ereport(ERROR,
							(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
							 errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
							  RelationGetRelationName(trigdata->tg_relation),
									NameStr(riinfo.conname)),
							 errdetail("MATCH FULL does not allow mixing of null and nonnull key values.")));
					heap_close(pk_rel, RowShareLock);
					return PointerGetDatum(NULL);

				case FKCONSTR_MATCH_UNSPECIFIED:

					/*
					 * MATCH <unspecified> - if ANY column is null, we have a
					 * match.
					 */
					heap_close(pk_rel, RowShareLock);
					return PointerGetDatum(NULL);

				case FKCONSTR_MATCH_PARTIAL:

					/*
					 * MATCH PARTIAL - all non-null columns must match. (not
					 * implemented, can be done by modifying the query below
					 * to only include non-null columns, or by writing a
					 * special version here)
					 */
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("MATCH PARTIAL not yet implemented")));
					heap_close(pk_rel, RowShareLock);
					return PointerGetDatum(NULL);
			}

		case RI_KEYS_NONE_NULL:

			/*
			 * Have a full qualified key - continue below for all three kinds
			 * of MATCH.
			 */
			break;
	}

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

	/*
	 * Fetch or prepare a saved plan for the real check
	 */
	if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
	{
		StringInfoData querybuf;
		char		pkrelname[MAX_QUOTED_REL_NAME_LEN];
		char		attname[MAX_QUOTED_NAME_LEN];
		char		paramname[16];
		const char *querysep;
		Oid			queryoids[RI_MAX_NUMKEYS];

		/* ----------
		 * The query string built is
		 *	SELECT 1 FROM ONLY <pktable> WHERE pkatt1 = $1 [AND ...] FOR SHARE
		 * The type id's for the $ parameters are those of the
		 * corresponding FK attributes.
		 * ----------
		 */
		initStringInfo(&querybuf);
		quoteRelationName(pkrelname, pk_rel);
		appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x", pkrelname);
		querysep = "WHERE";
		for (i = 0; i < riinfo.nkeys; i++)
		{
			Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
			Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

			quoteOneName(attname,
						 RIAttName(pk_rel, riinfo.pk_attnums[i]));
			sprintf(paramname, "$%d", i + 1);
			ri_GenerateQual(&querybuf, querysep,
							attname, pk_type,
							riinfo.pf_eq_oprs[i],
							paramname, fk_type);
			querysep = "AND";
			queryoids[i] = fk_type;
		}
		appendStringInfo(&querybuf, " FOR SHARE OF x");

		/* Prepare and save the plan */
		qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
							 &qkey, fk_rel, pk_rel, true);
	}

	/*
	 * Now check that foreign key exists in PK table
	 */
	ri_PerformCheck(&qkey, qplan,
					fk_rel, pk_rel,
					NULL, new_row,
					false,
					SPI_OK_SELECT,
					NameStr(riinfo.conname));

	if (SPI_finish() != SPI_OK_FINISH)
		elog(ERROR, "SPI_finish failed");

	heap_close(pk_rel, RowShareLock);

	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_check_ins -
 *
 *	Check foreign key existence at insert event on FK table.
 * ----------
 */
Datum
RI_FKey_check_ins(PG_FUNCTION_ARGS)
{
	return RI_FKey_check(fcinfo);
}


/* ----------
 * RI_FKey_check_upd -
 *
 *	Check foreign key existence at update event on FK table.
 * ----------
 */
Datum
RI_FKey_check_upd(PG_FUNCTION_ARGS)
{
	return RI_FKey_check(fcinfo);
}


/* ----------
 * ri_Check_Pk_Match
 *
 * Check for matching value of old pk row in current state for
 * noaction triggers. Returns false if no row was found and a fk row
 * could potentially be referencing this row, true otherwise.
 * ----------
 */
static bool
ri_Check_Pk_Match(Relation pk_rel, Relation fk_rel,
				  HeapTuple old_row,
				  const RI_ConstraintInfo *riinfo)
{
	SPIPlanPtr	qplan;
	RI_QueryKey qkey;
	int			i;
	bool		result;

	ri_BuildQueryKeyPkCheck(&qkey, riinfo, RI_PLAN_CHECK_LOOKUPPK);

	switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
	{
		case RI_KEYS_ALL_NULL:

			/*
			 * No check - nothing could have been referencing this row anyway.
			 */
			return true;

		case RI_KEYS_SOME_NULL:

			/*
			 * This is the only case that differs between the three kinds of
			 * MATCH.
			 */
			switch (riinfo->confmatchtype)
			{
				case FKCONSTR_MATCH_FULL:
				case FKCONSTR_MATCH_UNSPECIFIED:

					/*
					 * MATCH <unspecified>/FULL  - if ANY column is null, we
					 * can't be matching to this row already.
					 */
					return true;

				case FKCONSTR_MATCH_PARTIAL:

					/*
					 * MATCH PARTIAL - all non-null columns must match. (not
					 * implemented, can be done by modifying the query below
					 * to only include non-null columns, or by writing a
					 * special version here)
					 */
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("MATCH PARTIAL not yet implemented")));
					break;
			}

		case RI_KEYS_NONE_NULL:

			/*
			 * Have a full qualified key - continue below for all three kinds
			 * of MATCH.
			 */
			break;
	}

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

	/*
	 * Fetch or prepare a saved plan for the real check
	 */
	if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
	{
		StringInfoData querybuf;
		char		pkrelname[MAX_QUOTED_REL_NAME_LEN];
		char		attname[MAX_QUOTED_NAME_LEN];
		char		paramname[16];
		const char *querysep;
		Oid			queryoids[RI_MAX_NUMKEYS];

		/* ----------
		 * The query string built is
		 *	SELECT 1 FROM ONLY <pktable> WHERE pkatt1 = $1 [AND ...] FOR SHARE
		 * The type id's for the $ parameters are those of the
		 * PK attributes themselves.
		 * ----------
		 */
		initStringInfo(&querybuf);
		quoteRelationName(pkrelname, pk_rel);
		appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x", pkrelname);
		querysep = "WHERE";
		for (i = 0; i < riinfo->nkeys; i++)
		{
			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);

			quoteOneName(attname,
						 RIAttName(pk_rel, riinfo->pk_attnums[i]));
			sprintf(paramname, "$%d", i + 1);
			ri_GenerateQual(&querybuf, querysep,
							attname, pk_type,
							riinfo->pp_eq_oprs[i],
							paramname, pk_type);
			querysep = "AND";
			queryoids[i] = pk_type;
		}
		appendStringInfo(&querybuf, " FOR SHARE OF x");

		/* Prepare and save the plan */
		qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
							 &qkey, fk_rel, pk_rel, true);
	}

	/*
	 * We have a plan now. Run it.
	 */
	result = ri_PerformCheck(&qkey, qplan,
							 fk_rel, pk_rel,
							 old_row, NULL,
							 true,		/* treat like update */
							 SPI_OK_SELECT, NULL);

	if (SPI_finish() != SPI_OK_FINISH)
		elog(ERROR, "SPI_finish failed");

	return result;
}


/* ----------
 * RI_FKey_noaction_del -
 *
 *	Give an error and roll back the current transaction if the
 *	delete has resulted in a violation of the given referential
 *	integrity constraint.
 * ----------
 */
Datum
RI_FKey_noaction_del(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_noaction_del", RI_TRIGTYPE_DELETE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowShareLock mode since that's what our eventual
	 * SELECT FOR SHARE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowShareLock);
	pk_rel = trigdata->tg_relation;
	old_row = trigdata->tg_trigtuple;

	if (ri_Check_Pk_Match(pk_rel, fk_rel, old_row, &riinfo))
	{
		/*
		 * There's either another row, or no row could match this one.  In
		 * either case, we don't need to do the check.
		 */
		heap_close(fk_rel, RowShareLock);
		return PointerGetDatum(NULL);
	}

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) iv):
			 *		MATCH <unspecified> or MATCH FULL
			 *			... ON DELETE CASCADE
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_NOACTION_DEL_CHECKREF);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No check - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowShareLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

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

			/*
			 * Fetch or prepare a saved plan for the restrict delete lookup if
			 * foreign references exist
			 */
			if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	SELECT 1 FROM ONLY <fktable> WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x",
								 fkrelname);
				querysep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&querybuf, querysep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfo(&querybuf, " FOR SHARE OF x");

				/* Prepare and save the plan */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, true);
			}

			/*
			 * We have a plan now. Run it to check for existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_SELECT,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowShareLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL restrict delete.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_noaction_upd -
 *
 *	Give an error and roll back the current transaction if the
 *	update has resulted in a violation of the given referential
 *	integrity constraint.
 * ----------
 */
Datum
RI_FKey_noaction_upd(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	new_row;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_noaction_upd", RI_TRIGTYPE_UPDATE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the new and
	 * old tuple.
	 *
	 * fk_rel is opened in RowShareLock mode since that's what our eventual
	 * SELECT FOR SHARE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowShareLock);
	pk_rel = trigdata->tg_relation;
	new_row = trigdata->tg_newtuple;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) iv):
			 *		MATCH <unspecified> or MATCH FULL
			 *			... ON DELETE CASCADE
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_NOACTION_UPD_CHECKREF);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No check - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowShareLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

			/*
			 * No need to check anything if old and new keys are equal
			 */
			if (ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true))
			{
				heap_close(fk_rel, RowShareLock);
				return PointerGetDatum(NULL);
			}

			if (ri_Check_Pk_Match(pk_rel, fk_rel, old_row, &riinfo))
			{
				/*
				 * There's either another row, or no row could match this one.
				 * In either case, we don't need to do the check.
				 */
				heap_close(fk_rel, RowShareLock);
				return PointerGetDatum(NULL);
			}

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

			/*
			 * Fetch or prepare a saved plan for the noaction update lookup if
			 * foreign references exist
			 */
			if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	SELECT 1 FROM ONLY <fktable> WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x",
								 fkrelname);
				querysep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&querybuf, querysep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfo(&querybuf, " FOR SHARE OF x");

				/* Prepare and save the plan */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, true);
			}

			/*
			 * We have a plan now. Run it to check for existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_SELECT,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowShareLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL noaction update.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_cascade_del -
 *
 *	Cascaded delete foreign key references at delete event on PK table.
 * ----------
 */
Datum
RI_FKey_cascade_del(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_cascade_del", RI_TRIGTYPE_DELETE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual DELETE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) i):
			 *		MATCH <unspecified> or MATCH FULL
			 *			... ON DELETE CASCADE
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_CASCADE_DEL_DODELETE);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No check - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

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

			/*
			 * Fetch or prepare a saved plan for the cascaded delete
			 */
			if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	DELETE FROM ONLY <fktable> WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "DELETE FROM ONLY %s", fkrelname);
				querysep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&querybuf, querysep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = "AND";
					queryoids[i] = pk_type;
				}

				/* Prepare and save the plan */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, true);
			}

			/*
			 * We have a plan now. Build up the arguments from the key values
			 * in the deleted PK tuple and delete the referencing rows
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_DELETE,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL cascaded delete.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_cascade_upd -
 *
 *	Cascaded update/delete foreign key references at update event on PK table.
 * ----------
 */
Datum
RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	new_row;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;
	int			j;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_cascade_upd", RI_TRIGTYPE_UPDATE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the new and
	 * old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual UPDATE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	new_row = trigdata->tg_newtuple;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 7) a) i):
			 *		MATCH <unspecified> or MATCH FULL
			 *			... ON UPDATE CASCADE
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_CASCADE_UPD_DOUPDATE);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No update - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

			/*
			 * No need to do anything if old and new keys are equal
			 */
			if (ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true))
			{
				heap_close(fk_rel, RowExclusiveLock);
				return PointerGetDatum(NULL);
			}

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

			/*
			 * Fetch or prepare a saved plan for the cascaded update of
			 * foreign references
			 */
			if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				StringInfoData qualbuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS * 2];

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = $1 [, ...]
				 *			WHERE $n = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.  Note that we are assuming
				 * there is an assignment cast from the PK to the FK type;
				 * else the parser will fail.
				 * ----------
				 */
				initStringInfo(&querybuf);
				initStringInfo(&qualbuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
				querysep = "";
				qualsep = "WHERE";
				for (i = 0, j = riinfo.nkeys; i < riinfo.nkeys; i++, j++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					appendStringInfo(&querybuf,
									 "%s %s = $%d",
									 querysep, attname, i + 1);
					sprintf(paramname, "$%d", j + 1);
					ri_GenerateQual(&qualbuf, qualsep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = ",";
					qualsep = "AND";
					queryoids[i] = pk_type;
					queryoids[j] = pk_type;
				}
				appendStringInfoString(&querybuf, qualbuf.data);

				/* Prepare and save the plan */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys * 2, queryoids,
									 &qkey, fk_rel, pk_rel, true);
			}

			/*
			 * We have a plan now. Run it to update the existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, new_row,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL cascade update.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_restrict_del -
 *
 *	Restrict delete from PK table to rows unreferenced by foreign key.
 *
 *	SQL3 intends that this referential action occur BEFORE the
 *	update is performed, rather than after.  This appears to be
 *	the only difference between "NO ACTION" and "RESTRICT".
 *
 *	For now, however, we treat "RESTRICT" and "NO ACTION" as
 *	equivalent.
 * ----------
 */
Datum
RI_FKey_restrict_del(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_restrict_del", RI_TRIGTYPE_DELETE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowShareLock mode since that's what our eventual
	 * SELECT FOR SHARE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowShareLock);
	pk_rel = trigdata->tg_relation;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) iv):
			 *		MATCH <unspecified> or MATCH FULL
			 *			... ON DELETE CASCADE
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_RESTRICT_DEL_CHECKREF);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No check - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowShareLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

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

			/*
			 * Fetch or prepare a saved plan for the restrict delete lookup if
			 * foreign references exist
			 */
			if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	SELECT 1 FROM ONLY <fktable> WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x",
								 fkrelname);
				querysep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&querybuf, querysep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfo(&querybuf, " FOR SHARE OF x");

				/* Prepare and save the plan */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, true);
			}

			/*
			 * We have a plan now. Run it to check for existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_SELECT,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowShareLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL restrict delete.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_restrict_upd -
 *
 *	Restrict update of PK to rows unreferenced by foreign key.
 *
 *	SQL3 intends that this referential action occur BEFORE the
 *	update is performed, rather than after.  This appears to be
 *	the only difference between "NO ACTION" and "RESTRICT".
 *
 *	For now, however, we treat "RESTRICT" and "NO ACTION" as
 *	equivalent.
 * ----------
 */
Datum
RI_FKey_restrict_upd(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	new_row;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_restrict_upd", RI_TRIGTYPE_UPDATE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the new and
	 * old tuple.
	 *
	 * fk_rel is opened in RowShareLock mode since that's what our eventual
	 * SELECT FOR SHARE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowShareLock);
	pk_rel = trigdata->tg_relation;
	new_row = trigdata->tg_newtuple;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) iv):
			 *		MATCH <unspecified> or MATCH FULL
			 *			... ON DELETE CASCADE
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_RESTRICT_UPD_CHECKREF);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No check - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowShareLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

			/*
			 * No need to check anything if old and new keys are equal
			 */
			if (ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true))
			{
				heap_close(fk_rel, RowShareLock);
				return PointerGetDatum(NULL);
			}

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

			/*
			 * Fetch or prepare a saved plan for the restrict update lookup if
			 * foreign references exist
			 */
			if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	SELECT 1 FROM ONLY <fktable> WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x",
								 fkrelname);
				querysep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&querybuf, querysep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfo(&querybuf, " FOR SHARE OF x");

				/* Prepare and save the plan */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, true);
			}

			/*
			 * We have a plan now. Run it to check for existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_SELECT,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowShareLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL restrict update.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setnull_del -
 *
 *	Set foreign key references to NULL values at delete event on PK table.
 * ----------
 */
Datum
RI_FKey_setnull_del(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_setnull_del", RI_TRIGTYPE_DELETE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual UPDATE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) ii):
			 *		MATCH <UNSPECIFIED> or MATCH FULL
			 *			... ON DELETE SET NULL
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_SETNULL_DEL_DOUPDATE);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No update - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

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

			/*
			 * Fetch or prepare a saved plan for the set null delete operation
			 */
			if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				StringInfoData qualbuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = NULL [, ...]
				 *			WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				initStringInfo(&qualbuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
				querysep = "";
				qualsep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					appendStringInfo(&querybuf,
									 "%s %s = NULL",
									 querysep, attname);
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&qualbuf, qualsep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = ",";
					qualsep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfoString(&querybuf, qualbuf.data);

				/* Prepare and save the plan */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, true);
			}

			/*
			 * We have a plan now. Run it to check for existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL set null delete.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setnull_upd -
 *
 *	Set foreign key references to NULL at update event on PK table.
 * ----------
 */
Datum
RI_FKey_setnull_upd(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	new_row;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;
	int			i;
	bool		use_cached_query;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_setnull_upd", RI_TRIGTYPE_UPDATE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual UPDATE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	new_row = trigdata->tg_newtuple;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 7) a) ii) 2):
			 *		MATCH FULL
			 *			... ON UPDATE SET NULL
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_SETNULL_UPD_DOUPDATE);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No update - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

			/*
			 * No need to do anything if old and new keys are equal
			 */
			if (ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true))
			{
				heap_close(fk_rel, RowExclusiveLock);
				return PointerGetDatum(NULL);
			}

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

			/*
			 * "MATCH <unspecified>" only changes columns corresponding to the
			 * referenced columns that have changed in pk_rel.	This means the
			 * "SET attrn=NULL [, attrn=NULL]" string will be change as well.
			 * In this case, we need to build a temporary plan rather than use
			 * our cached plan, unless the update happens to change all
			 * columns in the key.	Fortunately, for the most common case of a
			 * single-column foreign key, this will be true.
			 *
			 * In case you're wondering, the inequality check works because we
			 * know that the old key value has no NULLs (see above).
			 */

			use_cached_query = (riinfo.confmatchtype == FKCONSTR_MATCH_FULL) ||
				ri_AllKeysUnequal(pk_rel, old_row, new_row,
								  &riinfo, true);

			/*
			 * Fetch or prepare a saved plan for the set null update operation
			 * if possible, or build a temporary plan if not.
			 */
			if (!use_cached_query ||
				(qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				StringInfoData querybuf;
				StringInfoData qualbuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = NULL [, ...]
				 *			WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				initStringInfo(&qualbuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
				querysep = "";
				qualsep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));

					/*
					 * MATCH <unspecified> - only change columns corresponding
					 * to changed columns in pk_rel's key
					 */
					if (riinfo.confmatchtype == FKCONSTR_MATCH_FULL ||
						!ri_OneKeyEqual(pk_rel, i, old_row, new_row,
										&riinfo, true))
					{
						appendStringInfo(&querybuf,
										 "%s %s = NULL",
										 querysep, attname);
						querysep = ",";
					}
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&qualbuf, qualsep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					qualsep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfoString(&querybuf, qualbuf.data);

				/*
				 * Prepare the plan.  Save it only if we're building the
				 * "standard" plan.
				 */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel,
									 use_cached_query);
			}

			/*
			 * We have a plan now. Run it to update the existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL set null update.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setdefault_del -
 *
 *	Set foreign key references to defaults at delete event on PK table.
 * ----------
 */
Datum
RI_FKey_setdefault_del(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_del", RI_TRIGTYPE_DELETE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual UPDATE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) iii):
			 *		MATCH <UNSPECIFIED> or MATCH FULL
			 *			... ON DELETE SET DEFAULT
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_SETNULL_DEL_DOUPDATE);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No update - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

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

			/*
			 * Prepare a plan for the set default delete operation.
			 * Unfortunately we need to do it on every invocation because the
			 * default value could potentially change between calls.
			 */
			{
				StringInfoData querybuf;
				StringInfoData qualbuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS];
				int			i;

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = DEFAULT [, ...]
				 *			WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				initStringInfo(&qualbuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
				querysep = "";
				qualsep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));
					appendStringInfo(&querybuf,
									 "%s %s = DEFAULT",
									 querysep, attname);
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&qualbuf, qualsep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					querysep = ",";
					qualsep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfoString(&querybuf, qualbuf.data);

				/* Prepare the plan, don't save it */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, false);
			}

			/*
			 * We have a plan now. Run it to update the existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			/*
			 * In the case we delete the row who's key is equal to the default
			 * values AND a referencing row in the foreign key table exists,
			 * we would just have updated it to the same values. We need to do
			 * another lookup now and in case a reference exists, abort the
			 * operation. That is already implemented in the NO ACTION
			 * trigger.
			 */
			RI_FKey_noaction_del(fcinfo);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL set null delete.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setdefault_upd -
 *
 *	Set foreign key references to defaults at update event on PK table.
 * ----------
 */
Datum
RI_FKey_setdefault_upd(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	new_row;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	SPIPlanPtr	qplan;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_upd", RI_TRIGTYPE_UPDATE);

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo,
						   trigdata->tg_trigger, trigdata->tg_relation, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual UPDATE will get on it.
	 */
	fk_rel = heap_open(riinfo.fk_relid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	new_row = trigdata->tg_newtuple;
	old_row = trigdata->tg_trigtuple;

	switch (riinfo.confmatchtype)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 7) a) iii):
			 *		MATCH <UNSPECIFIED> or MATCH FULL
			 *			... ON UPDATE SET DEFAULT
			 * ----------
			 */
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_SETNULL_DEL_DOUPDATE);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No update - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

			/*
			 * No need to do anything if old and new keys are equal
			 */
			if (ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true))
			{
				heap_close(fk_rel, RowExclusiveLock);
				return PointerGetDatum(NULL);
			}

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

			/*
			 * Prepare a plan for the set default delete operation.
			 * Unfortunately we need to do it on every invocation because the
			 * default value could potentially change between calls.
			 */
			{
				StringInfoData querybuf;
				StringInfoData qualbuf;
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				char		paramname[16];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS];
				int			i;

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = DEFAULT [, ...]
				 *			WHERE $1 = fkatt1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes.
				 * ----------
				 */
				initStringInfo(&querybuf);
				initStringInfo(&qualbuf);
				quoteRelationName(fkrelname, fk_rel);
				appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
				querysep = "";
				qualsep = "WHERE";
				for (i = 0; i < riinfo.nkeys; i++)
				{
					Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
					Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

					quoteOneName(attname,
								 RIAttName(fk_rel, riinfo.fk_attnums[i]));

					/*
					 * MATCH <unspecified> - only change columns corresponding
					 * to changed columns in pk_rel's key
					 */
					if (riinfo.confmatchtype == FKCONSTR_MATCH_FULL ||
						!ri_OneKeyEqual(pk_rel, i, old_row, new_row,
										&riinfo, true))
					{
						appendStringInfo(&querybuf,
										 "%s %s = DEFAULT",
										 querysep, attname);
						querysep = ",";
					}
					sprintf(paramname, "$%d", i + 1);
					ri_GenerateQual(&qualbuf, qualsep,
									paramname, pk_type,
									riinfo.pf_eq_oprs[i],
									attname, fk_type);
					qualsep = "AND";
					queryoids[i] = pk_type;
				}
				appendStringInfoString(&querybuf, qualbuf.data);

				/* Prepare the plan, don't save it */
				qplan = ri_PlanCheck(querybuf.data, riinfo.nkeys, queryoids,
									 &qkey, fk_rel, pk_rel, false);
			}

			/*
			 * We have a plan now. Run it to update the existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							NameStr(riinfo.conname));

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			/*
			 * In the case we updated the row who's key was equal to the
			 * default values AND a referencing row in the foreign key table
			 * exists, we would just have updated it to the same values. We
			 * need to do another lookup now and in case a reference exists,
			 * abort the operation. That is already implemented in the NO
			 * ACTION trigger.
			 */
			RI_FKey_noaction_upd(fcinfo);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL set null delete.
			 */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid confmatchtype");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_keyequal_upd_pk -
 *
 *	Check if we have a key change on an update to a PK relation. This is
 *	used by the AFTER trigger queue manager to see if it can skip queuing
 *	an instance of an RI trigger.
 * ----------
 */
bool
RI_FKey_keyequal_upd_pk(Trigger *trigger, Relation pk_rel,
						HeapTuple old_row, HeapTuple new_row)
{
	RI_ConstraintInfo riinfo;
	Relation	fk_rel;
	RI_QueryKey qkey;

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo, trigger, pk_rel, true);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return true;

	fk_rel = heap_open(riinfo.fk_relid, AccessShareLock);

	switch (riinfo.confmatchtype)
	{
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_KEYEQUAL_UPD);

			heap_close(fk_rel, AccessShareLock);

			/* Return if key's are equal */
			return ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true);

			/* Handle MATCH PARTIAL set null delete. */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			break;
	}

	/* Never reached */
	elog(ERROR, "invalid confmatchtype");
	return false;
}

/* ----------
 * RI_FKey_keyequal_upd_fk -
 *
 *	Check if we have a key change on an update to an FK relation. This is
 *	used by the AFTER trigger queue manager to see if it can skip queuing
 *	an instance of an RI trigger.
 * ----------
 */
bool
RI_FKey_keyequal_upd_fk(Trigger *trigger, Relation fk_rel,
						HeapTuple old_row, HeapTuple new_row)
{
	RI_ConstraintInfo riinfo;
	Relation	pk_rel;
	RI_QueryKey qkey;

	/*
	 * Get arguments.
	 */
	ri_FetchConstraintInfo(&riinfo, trigger, fk_rel, false);

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (riinfo.nkeys == 0)
		return true;

	pk_rel = heap_open(riinfo.pk_relid, AccessShareLock);

	switch (riinfo.confmatchtype)
	{
		case FKCONSTR_MATCH_UNSPECIFIED:
		case FKCONSTR_MATCH_FULL:
			ri_BuildQueryKeyFull(&qkey, &riinfo,
								 RI_PLAN_KEYEQUAL_UPD);
			heap_close(pk_rel, AccessShareLock);

			/* Return if key's are equal */
			return ri_KeysEqual(fk_rel, old_row, new_row, &riinfo, false);

			/* Handle MATCH PARTIAL set null delete. */
		case FKCONSTR_MATCH_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			break;
	}

	/* Never reached */
	elog(ERROR, "invalid confmatchtype");
	return false;
}

/* ----------
 * RI_Initial_Check -
 *
 *	Check an entire table for non-matching values using a single query.
 *	This is not a trigger procedure, but is called during ALTER TABLE
 *	ADD FOREIGN KEY to validate the initial table contents.
 *
 *	We expect that an exclusive lock has been taken on rel and pkrel;
 *	hence, we do not need to lock individual rows for the check.
 *
 *	If the check fails because the current user doesn't have permissions
 *	to read both tables, return false to let our caller know that they will
 *	need to do something else to check the constraint.
 * ----------
 */
bool
RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
{
	RI_ConstraintInfo riinfo;
	const char *constrname = trigger->tgname;
	StringInfoData querybuf;
	char		pkrelname[MAX_QUOTED_REL_NAME_LEN];
	char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
	char		pkattname[MAX_QUOTED_NAME_LEN + 3];
	char		fkattname[MAX_QUOTED_NAME_LEN + 3];
	const char *sep;
	int			i;
	int			old_work_mem;
	char		workmembuf[32];
	int			spi_result;
	SPIPlanPtr	qplan;

	/*
	 * Check to make sure current user has enough permissions to do the test
	 * query.  (If not, caller can fall back to the trigger method, which
	 * works because it changes user IDs on the fly.)
	 *
	 * XXX are there any other show-stopper conditions to check?
	 */
	if (pg_class_aclcheck(RelationGetRelid(fk_rel), GetUserId(), ACL_SELECT) != ACLCHECK_OK)
		return false;
	if (pg_class_aclcheck(RelationGetRelid(pk_rel), GetUserId(), ACL_SELECT) != ACLCHECK_OK)
		return false;

	ri_FetchConstraintInfo(&riinfo, trigger, fk_rel, false);

	/*----------
	 * The query string built is:
	 *	SELECT fk.keycols FROM ONLY relname fk
	 *	 LEFT OUTER JOIN ONLY pkrelname pk
	 *	 ON (pk.pkkeycol1=fk.keycol1 [AND ...])
	 *	 WHERE pk.pkkeycol1 IS NULL AND
	 * For MATCH unspecified:
	 *	 (fk.keycol1 IS NOT NULL [AND ...])
	 * For MATCH FULL:
	 *	 (fk.keycol1 IS NOT NULL [OR ...])
	 *----------
	 */
	initStringInfo(&querybuf);
	appendStringInfo(&querybuf, "SELECT ");
	sep = "";
	for (i = 0; i < riinfo.nkeys; i++)
	{
		quoteOneName(fkattname,
					 RIAttName(fk_rel, riinfo.fk_attnums[i]));
		appendStringInfo(&querybuf, "%sfk.%s", sep, fkattname);
		sep = ", ";
	}

	quoteRelationName(pkrelname, pk_rel);
	quoteRelationName(fkrelname, fk_rel);
	appendStringInfo(&querybuf,
					 " FROM ONLY %s fk LEFT OUTER JOIN ONLY %s pk ON",
					 fkrelname, pkrelname);

	strcpy(pkattname, "pk.");
	strcpy(fkattname, "fk.");
	sep = "(";
	for (i = 0; i < riinfo.nkeys; i++)
	{
		Oid			pk_type = RIAttType(pk_rel, riinfo.pk_attnums[i]);
		Oid			fk_type = RIAttType(fk_rel, riinfo.fk_attnums[i]);

		quoteOneName(pkattname + 3,
					 RIAttName(pk_rel, riinfo.pk_attnums[i]));
		quoteOneName(fkattname + 3,
					 RIAttName(fk_rel, riinfo.fk_attnums[i]));
		ri_GenerateQual(&querybuf, sep,
						pkattname, pk_type,
						riinfo.pf_eq_oprs[i],
						fkattname, fk_type);
		sep = "AND";
	}

	/*
	 * It's sufficient to test any one pk attribute for null to detect a join
	 * failure.
	 */
	quoteOneName(pkattname, RIAttName(pk_rel, riinfo.pk_attnums[0]));
	appendStringInfo(&querybuf, ") WHERE pk.%s IS NULL AND (", pkattname);

	sep = "";
	for (i = 0; i < riinfo.nkeys; i++)
	{
		quoteOneName(fkattname, RIAttName(fk_rel, riinfo.fk_attnums[i]));
		appendStringInfo(&querybuf,
						 "%sfk.%s IS NOT NULL",
						 sep, fkattname);
		switch (riinfo.confmatchtype)
		{
			case FKCONSTR_MATCH_UNSPECIFIED:
				sep = " AND ";
				break;
			case FKCONSTR_MATCH_FULL:
				sep = " OR ";
				break;
			case FKCONSTR_MATCH_PARTIAL:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("MATCH PARTIAL not yet implemented")));
				break;
			default:
				elog(ERROR, "unrecognized match type: %d",
					 riinfo.confmatchtype);
				break;
		}
	}
	appendStringInfo(&querybuf, ")");

	/*
	 * Temporarily increase work_mem so that the check query can be executed
	 * more efficiently.  It seems okay to do this because the query is simple
	 * enough to not use a multiple of work_mem, and one typically would not
	 * have many large foreign-key validations happening concurrently.	So
	 * this seems to meet the criteria for being considered a "maintenance"
	 * operation, and accordingly we use maintenance_work_mem.
	 *
	 * We do the equivalent of "SET LOCAL work_mem" so that transaction abort
	 * will restore the old value if we lose control due to an error.
	 */
	old_work_mem = work_mem;
	snprintf(workmembuf, sizeof(workmembuf), "%d", maintenance_work_mem);
	(void) set_config_option("work_mem", workmembuf,
							 PGC_USERSET, PGC_S_SESSION,
							 GUC_ACTION_LOCAL, true);

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

	/*
	 * Generate the plan.  We don't need to cache it, and there are no
	 * arguments to the plan.
	 */
	qplan = SPI_prepare(querybuf.data, 0, NULL);

	if (qplan == NULL)
		elog(ERROR, "SPI_prepare returned %d for %s",
			 SPI_result, querybuf.data);

	/*
	 * Run the plan.  For safety we force a current snapshot to be used. (In
	 * serializable mode, this arguably violates serializability, but we
	 * really haven't got much choice.)  We need at most one tuple returned,
	 * so pass limit = 1.
	 */
	spi_result = SPI_execute_snapshot(qplan,
									  NULL, NULL,
									  CopySnapshot(GetLatestSnapshot()),
									  InvalidSnapshot,
									  true, false, 1);

	/* Check result */
	if (spi_result != SPI_OK_SELECT)
		elog(ERROR, "SPI_execute_snapshot returned %d", spi_result);

	/* Did we find a tuple violating the constraint? */
	if (SPI_processed > 0)
	{
		HeapTuple	tuple = SPI_tuptable->vals[0];
		TupleDesc	tupdesc = SPI_tuptable->tupdesc;
		RI_QueryKey qkey;

		/*
		 * If it's MATCH FULL, and there are any nulls in the FK keys,
		 * complain about that rather than the lack of a match.  MATCH FULL
		 * disallows partially-null FK rows.
		 */
		if (riinfo.confmatchtype == FKCONSTR_MATCH_FULL)
		{
			bool		isnull = false;

			for (i = 1; i <= riinfo.nkeys; i++)
			{
				(void) SPI_getbinval(tuple, tupdesc, i, &isnull);
				if (isnull)
					break;
			}
			if (isnull)
				ereport(ERROR,
						(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
						 errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
								RelationGetRelationName(fk_rel),
								constrname),
						 errdetail("MATCH FULL does not allow mixing of null and nonnull key values.")));
		}

		/*
		 * Although we didn't cache the query, we need to set up a fake query
		 * key to pass to ri_ReportViolation.
		 */
		MemSet(&qkey, 0, sizeof(qkey));
		qkey.constr_queryno = RI_PLAN_CHECK_LOOKUPPK;
		qkey.nkeypairs = riinfo.nkeys;
		for (i = 0; i < riinfo.nkeys; i++)
			qkey.keypair[i][RI_KEYPAIR_FK_IDX] = i + 1;

		ri_ReportViolation(&qkey, constrname,
						   pk_rel, fk_rel,
						   tuple, tupdesc,
						   false);
	}

	if (SPI_finish() != SPI_OK_FINISH)
		elog(ERROR, "SPI_finish failed");

	/*
	 * Restore work_mem for the remainder of the current transaction. This is
	 * another SET LOCAL, so it won't affect the session value.
	 */
	snprintf(workmembuf, sizeof(workmembuf), "%d", old_work_mem);
	(void) set_config_option("work_mem", workmembuf,
							 PGC_USERSET, PGC_S_SESSION,
							 GUC_ACTION_LOCAL, true);

	return true;
}


/* ----------
 * Local functions below
 * ----------
 */


/*
 * quoteOneName --- safely quote a single SQL name
 *
 * buffer must be MAX_QUOTED_NAME_LEN long (includes room for \0)
 */
static void
quoteOneName(char *buffer, const char *name)
{
	/* Rather than trying to be smart, just always quote it. */
	*buffer++ = '"';
	while (*name)
	{
		if (*name == '"')
			*buffer++ = '"';
		*buffer++ = *name++;
	}
	*buffer++ = '"';
	*buffer = '\0';
}

/*
 * quoteRelationName --- safely quote a fully qualified relation name
 *
 * buffer must be MAX_QUOTED_REL_NAME_LEN long (includes room for \0)
 */
static void
quoteRelationName(char *buffer, Relation rel)
{
	quoteOneName(buffer, get_namespace_name(RelationGetNamespace(rel)));
	buffer += strlen(buffer);
	*buffer++ = '.';
	quoteOneName(buffer, RelationGetRelationName(rel));
}

/*
 * ri_GenerateQual --- generate a WHERE clause equating two variables
 *
 * The idea is to append " sep leftop op rightop" to buf.  The complexity
 * comes from needing to be sure that the parser will select the desired
 * operator.  We always name the operator using OPERATOR(schema.op) syntax
 * (readability isn't a big priority here).  We have to emit casts too,
 * if either input isn't already the input type of the operator.
 */
static void
ri_GenerateQual(StringInfo buf,
				const char *sep,
				const char *leftop, Oid leftoptype,
				Oid opoid,
				const char *rightop, Oid rightoptype)
{
	HeapTuple	opertup;
	Form_pg_operator operform;
	char	   *oprname;
	char	   *nspname;

	opertup = SearchSysCache(OPEROID,
							 ObjectIdGetDatum(opoid),
							 0, 0, 0);
	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);

	appendStringInfo(buf, " %s %s", sep, leftop);
	if (leftoptype != operform->oprleft)
		appendStringInfo(buf, "::%s", format_type_be(operform->oprleft));
	appendStringInfo(buf, " OPERATOR(%s.", quote_identifier(nspname));
	appendStringInfoString(buf, oprname);
	appendStringInfo(buf, ") %s", rightop);
	if (rightoptype != operform->oprright)
		appendStringInfo(buf, "::%s", format_type_be(operform->oprright));

	ReleaseSysCache(opertup);
}

/* ----------
 * ri_BuildQueryKeyFull -
 *
 *	Build up a new hashtable key for a prepared SPI plan of a
 *	constraint trigger of MATCH FULL.
 *
 *		key: output argument, *key is filled in based on the other arguments
 *		riinfo: info from pg_constraint entry
 *		constr_queryno: an internal number of the query inside the proc
 *
 *	At least for MATCH FULL this builds a unique key per plan.
 * ----------
 */
static void
ri_BuildQueryKeyFull(RI_QueryKey *key, const RI_ConstraintInfo *riinfo,
					 int32 constr_queryno)
{
	int			i;

	MemSet(key, 0, sizeof(RI_QueryKey));
	key->constr_type = FKCONSTR_MATCH_FULL;
	key->constr_id = riinfo->constraint_id;
	key->constr_queryno = constr_queryno;
	key->fk_relid = riinfo->fk_relid;
	key->pk_relid = riinfo->pk_relid;
	key->nkeypairs = riinfo->nkeys;
	for (i = 0; i < riinfo->nkeys; i++)
	{
		key->keypair[i][RI_KEYPAIR_FK_IDX] = riinfo->fk_attnums[i];
		key->keypair[i][RI_KEYPAIR_PK_IDX] = riinfo->pk_attnums[i];
	}
}

/*
 * Check that RI trigger function was called in expected context
 */
static void
ri_CheckTrigger(FunctionCallInfo fcinfo, const char *funcname, int tgkind)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;

	if (!CALLED_AS_TRIGGER(fcinfo))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("function \"%s\" was not called by trigger manager", funcname)));

	/*
	 * Check proper event
	 */
	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
		!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
			   errmsg("function \"%s\" must be fired AFTER ROW", funcname)));

	switch (tgkind)
	{
		case RI_TRIGTYPE_INSERT:
			if (!TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
				ereport(ERROR,
						(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
						 errmsg("function \"%s\" must be fired for INSERT", funcname)));
			break;
		case RI_TRIGTYPE_UPDATE:
			if (!TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
				ereport(ERROR,
						(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
						 errmsg("function \"%s\" must be fired for UPDATE", funcname)));
			break;
		case RI_TRIGTYPE_INUP:
			if (!TRIGGER_FIRED_BY_INSERT(trigdata->tg_event) &&
				!TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
				ereport(ERROR,
						(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("function \"%s\" must be fired for INSERT or UPDATE",
						funcname)));
			break;
		case RI_TRIGTYPE_DELETE:
			if (!TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
				ereport(ERROR,
						(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
						 errmsg("function \"%s\" must be fired for DELETE", funcname)));
			break;
	}
}


/*
 * Fetch the pg_constraint entry for the FK constraint, and fill *riinfo
 */
static void
ri_FetchConstraintInfo(RI_ConstraintInfo *riinfo,
					   Trigger *trigger, Relation trig_rel, bool rel_is_pk)
{
	Oid			constraintOid = trigger->tgconstraint;
	HeapTuple	tup;
	Form_pg_constraint conForm;
	Datum		adatum;
	bool		isNull;
	ArrayType  *arr;
	int			numkeys;

	/*
	 * Check that the FK constraint's OID is available; it might not be if
	 * we've been invoked via an ordinary trigger or an old-style "constraint
	 * trigger".
	 */
	if (!OidIsValid(constraintOid))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
		  errmsg("no pg_constraint entry for trigger \"%s\" on table \"%s\"",
				 trigger->tgname, RelationGetRelationName(trig_rel)),
				 errhint("Remove this referential integrity trigger and its mates, then do ALTER TABLE ADD CONSTRAINT.")));

	/* OK, fetch the tuple */
	tup = SearchSysCache(CONSTROID,
						 ObjectIdGetDatum(constraintOid),
						 0, 0, 0);
	if (!HeapTupleIsValid(tup)) /* should not happen */
		elog(ERROR, "cache lookup failed for constraint %u", constraintOid);
	conForm = (Form_pg_constraint) GETSTRUCT(tup);

	/* Do some easy cross-checks against the trigger call data */
	if (rel_is_pk)
	{
		if (conForm->contype != CONSTRAINT_FOREIGN ||
			conForm->conrelid != trigger->tgconstrrelid ||
			conForm->confrelid != RelationGetRelid(trig_rel))
			elog(ERROR, "wrong pg_constraint entry for trigger \"%s\" on table \"%s\"",
				 trigger->tgname, RelationGetRelationName(trig_rel));
	}
	else
	{
		if (conForm->contype != CONSTRAINT_FOREIGN ||
			conForm->conrelid != RelationGetRelid(trig_rel) ||
			conForm->confrelid != trigger->tgconstrrelid)
			elog(ERROR, "wrong pg_constraint entry for trigger \"%s\" on table \"%s\"",
				 trigger->tgname, RelationGetRelationName(trig_rel));
	}

	/* And extract data */
	riinfo->constraint_id = constraintOid;
	memcpy(&riinfo->conname, &conForm->conname, sizeof(NameData));
	riinfo->pk_relid = conForm->confrelid;
	riinfo->fk_relid = conForm->conrelid;
	riinfo->confupdtype = conForm->confupdtype;
	riinfo->confdeltype = conForm->confdeltype;
	riinfo->confmatchtype = conForm->confmatchtype;

	/*
	 * We expect the arrays to be 1-D arrays of the right types; verify that.
	 * We don't need to use deconstruct_array() since the array data is just
	 * going to look like a C array of values.
	 */
	adatum = SysCacheGetAttr(CONSTROID, tup,
							 Anum_pg_constraint_conkey, &isNull);
	if (isNull)
		elog(ERROR, "null conkey for constraint %u", constraintOid);
	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
	numkeys = ARR_DIMS(arr)[0];
	if (ARR_NDIM(arr) != 1 ||
		numkeys < 0 ||
		numkeys > RI_MAX_NUMKEYS ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != INT2OID)
		elog(ERROR, "conkey is not a 1-D smallint array");
	riinfo->nkeys = numkeys;
	memcpy(riinfo->fk_attnums, ARR_DATA_PTR(arr), numkeys * sizeof(int16));
	if ((Pointer) arr != DatumGetPointer(adatum))
		pfree(arr);				/* free de-toasted copy, if any */

	adatum = SysCacheGetAttr(CONSTROID, tup,
							 Anum_pg_constraint_confkey, &isNull);
	if (isNull)
		elog(ERROR, "null confkey for constraint %u", constraintOid);
	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
	numkeys = ARR_DIMS(arr)[0];
	if (ARR_NDIM(arr) != 1 ||
		numkeys != riinfo->nkeys ||
		numkeys > RI_MAX_NUMKEYS ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != INT2OID)
		elog(ERROR, "confkey is not a 1-D smallint array");
	memcpy(riinfo->pk_attnums, ARR_DATA_PTR(arr), numkeys * sizeof(int16));
	if ((Pointer) arr != DatumGetPointer(adatum))
		pfree(arr);				/* free de-toasted copy, if any */

	adatum = SysCacheGetAttr(CONSTROID, tup,
							 Anum_pg_constraint_conpfeqop, &isNull);
	if (isNull)
		elog(ERROR, "null conpfeqop for constraint %u", constraintOid);
	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
	numkeys = ARR_DIMS(arr)[0];
	if (ARR_NDIM(arr) != 1 ||
		numkeys != riinfo->nkeys ||
		numkeys > RI_MAX_NUMKEYS ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != OIDOID)
		elog(ERROR, "conpfeqop is not a 1-D Oid array");
	memcpy(riinfo->pf_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
	if ((Pointer) arr != DatumGetPointer(adatum))
		pfree(arr);				/* free de-toasted copy, if any */

	adatum = SysCacheGetAttr(CONSTROID, tup,
							 Anum_pg_constraint_conppeqop, &isNull);
	if (isNull)
		elog(ERROR, "null conppeqop for constraint %u", constraintOid);
	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
	numkeys = ARR_DIMS(arr)[0];
	if (ARR_NDIM(arr) != 1 ||
		numkeys != riinfo->nkeys ||
		numkeys > RI_MAX_NUMKEYS ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != OIDOID)
		elog(ERROR, "conppeqop is not a 1-D Oid array");
	memcpy(riinfo->pp_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
	if ((Pointer) arr != DatumGetPointer(adatum))
		pfree(arr);				/* free de-toasted copy, if any */

	adatum = SysCacheGetAttr(CONSTROID, tup,
							 Anum_pg_constraint_conffeqop, &isNull);
	if (isNull)
		elog(ERROR, "null conffeqop for constraint %u", constraintOid);
	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
	numkeys = ARR_DIMS(arr)[0];
	if (ARR_NDIM(arr) != 1 ||
		numkeys != riinfo->nkeys ||
		numkeys > RI_MAX_NUMKEYS ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != OIDOID)
		elog(ERROR, "conffeqop is not a 1-D Oid array");
	memcpy(riinfo->ff_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
	if ((Pointer) arr != DatumGetPointer(adatum))
		pfree(arr);				/* free de-toasted copy, if any */

	ReleaseSysCache(tup);
}


/*
 * Prepare execution plan for a query to enforce an RI restriction
 *
 * If cache_plan is true, the plan is saved into our plan hashtable
 * so that we don't need to plan it again.
 */
static SPIPlanPtr
ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
			 RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel,
			 bool cache_plan)
{
	SPIPlanPtr	qplan;
	Relation	query_rel;
	Oid			save_userid;
	bool		save_secdefcxt;

	/*
	 * The query is always run against the FK table except when this is an
	 * update/insert trigger on the FK table itself - either
	 * RI_PLAN_CHECK_LOOKUPPK or RI_PLAN_CHECK_LOOKUPPK_NOCOLS
	 */
	if (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK ||
		qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK_NOCOLS)
		query_rel = pk_rel;
	else
		query_rel = fk_rel;

	/* Switch to proper UID to perform check as */
	GetUserIdAndContext(&save_userid, &save_secdefcxt);
	SetUserIdAndContext(RelationGetForm(query_rel)->relowner, true);

	/* Create the plan */
	qplan = SPI_prepare(querystr, nargs, argtypes);

	if (qplan == NULL)
		elog(ERROR, "SPI_prepare returned %d for %s", SPI_result, querystr);

	/* Restore UID */
	SetUserIdAndContext(save_userid, save_secdefcxt);

	/* Save the plan if requested */
	if (cache_plan)
	{
		qplan = SPI_saveplan(qplan);
		ri_HashPreparedPlan(qkey, qplan);
	}

	return qplan;
}

/*
 * Perform a query to enforce an RI restriction
 */
static bool
ri_PerformCheck(RI_QueryKey *qkey, SPIPlanPtr qplan,
				Relation fk_rel, Relation pk_rel,
				HeapTuple old_tuple, HeapTuple new_tuple,
				bool detectNewRows,
				int expect_OK, const char *constrname)
{
	Relation	query_rel,
				source_rel;
	int			key_idx;
	Snapshot	test_snapshot;
	Snapshot	crosscheck_snapshot;
	int			limit;
	int			spi_result;
	Oid			save_userid;
	bool		save_secdefcxt;
	Datum		vals[RI_MAX_NUMKEYS * 2];
	char		nulls[RI_MAX_NUMKEYS * 2];

	/*
	 * The query is always run against the FK table except when this is an
	 * update/insert trigger on the FK table itself - either
	 * RI_PLAN_CHECK_LOOKUPPK or RI_PLAN_CHECK_LOOKUPPK_NOCOLS
	 */
	if (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK ||
		qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK_NOCOLS)
		query_rel = pk_rel;
	else
		query_rel = fk_rel;

	/*
	 * The values for the query are taken from the table on which the trigger
	 * is called - it is normally the other one with respect to query_rel. An
	 * exception is ri_Check_Pk_Match(), which uses the PK table for both (the
	 * case when constrname == NULL)
	 */
	if (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK && constrname != NULL)
	{
		source_rel = fk_rel;
		key_idx = RI_KEYPAIR_FK_IDX;
	}
	else
	{
		source_rel = pk_rel;
		key_idx = RI_KEYPAIR_PK_IDX;
	}

	/* Extract the parameters to be passed into the query */
	if (new_tuple)
	{
		ri_ExtractValues(qkey, key_idx, source_rel, new_tuple,
						 vals, nulls);
		if (old_tuple)
			ri_ExtractValues(qkey, key_idx, source_rel, old_tuple,
							 vals + qkey->nkeypairs, nulls + qkey->nkeypairs);
	}
	else
	{
		ri_ExtractValues(qkey, key_idx, source_rel, old_tuple,
						 vals, nulls);
	}

	/*
	 * In READ COMMITTED mode, we just need to use an up-to-date regular
	 * snapshot, and we will see all rows that could be interesting. But in
	 * SERIALIZABLE mode, we can't change the transaction snapshot. If the
	 * caller passes detectNewRows == false then it's okay to do the query
	 * with the transaction snapshot; otherwise we use a current snapshot, and
	 * tell the executor to error out if it finds any rows under the current
	 * snapshot that wouldn't be visible per the transaction snapshot.
	 */
	if (IsXactIsoLevelSerializable && detectNewRows)
	{
		CommandCounterIncrement();		/* be sure all my own work is visible */
		test_snapshot = CopySnapshot(GetLatestSnapshot());
		crosscheck_snapshot = CopySnapshot(GetTransactionSnapshot());
	}
	else
	{
		/* the default SPI behavior is okay */
		test_snapshot = InvalidSnapshot;
		crosscheck_snapshot = InvalidSnapshot;
	}

	/*
	 * If this is a select query (e.g., for a 'no action' or 'restrict'
	 * trigger), we only need to see if there is a single row in the table,
	 * matching the key.  Otherwise, limit = 0 - because we want the query to
	 * affect ALL the matching rows.
	 */
	limit = (expect_OK == SPI_OK_SELECT) ? 1 : 0;

	/* Switch to proper UID to perform check as */
	GetUserIdAndContext(&save_userid, &save_secdefcxt);
	SetUserIdAndContext(RelationGetForm(query_rel)->relowner, true);

	/* Finally we can run the query. */
	spi_result = SPI_execute_snapshot(qplan,
									  vals, nulls,
									  test_snapshot, crosscheck_snapshot,
									  false, false, limit);

	/* Restore UID */
	SetUserIdAndContext(save_userid, save_secdefcxt);

	/* Check result */
	if (spi_result < 0)
		elog(ERROR, "SPI_execute_snapshot returned %d", spi_result);

	if (expect_OK >= 0 && spi_result != expect_OK)
		ri_ReportViolation(qkey, constrname ? constrname : "",
						   pk_rel, fk_rel,
						   new_tuple ? new_tuple : old_tuple,
						   NULL,
						   true);

	/* XXX wouldn't it be clearer to do this part at the caller? */
	if (constrname && expect_OK == SPI_OK_SELECT &&
	(SPI_processed == 0) == (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK))
		ri_ReportViolation(qkey, constrname,
						   pk_rel, fk_rel,
						   new_tuple ? new_tuple : old_tuple,
						   NULL,
						   false);

	return SPI_processed != 0;
}

/*
 * Extract fields from a tuple into Datum/nulls arrays
 */
static void
ri_ExtractValues(RI_QueryKey *qkey, int key_idx,
				 Relation rel, HeapTuple tuple,
				 Datum *vals, char *nulls)
{
	int			i;
	bool		isnull;

	for (i = 0; i < qkey->nkeypairs; i++)
	{
		vals[i] = SPI_getbinval(tuple, rel->rd_att,
								qkey->keypair[i][key_idx],
								&isnull);
		nulls[i] = isnull ? 'n' : ' ';
	}
}

/*
 * Produce an error report
 *
 * If the failed constraint was on insert/update to the FK table,
 * we want the key names and values extracted from there, and the error
 * message to look like 'key blah is not present in PK'.
 * Otherwise, the attr names and values come from the PK table and the
 * message looks like 'key blah is still referenced from FK'.
 */
static void
ri_ReportViolation(RI_QueryKey *qkey, const char *constrname,
				   Relation pk_rel, Relation fk_rel,
				   HeapTuple violator, TupleDesc tupdesc,
				   bool spi_err)
{
#define BUFLENGTH	512
	char		key_names[BUFLENGTH];
	char		key_values[BUFLENGTH];
	char	   *name_ptr = key_names;
	char	   *val_ptr = key_values;
	bool		onfk;
	int			idx,
				key_idx;

	if (spi_err)
		ereport(ERROR,
				(errcode(ERRCODE_INTERNAL_ERROR),
				 errmsg("referential integrity query on \"%s\" from constraint \"%s\" on \"%s\" gave unexpected result",
						RelationGetRelationName(pk_rel),
						constrname,
						RelationGetRelationName(fk_rel)),
				 errhint("This is most likely due to a rule having rewritten the query.")));

	/*
	 * Determine which relation to complain about.	If tupdesc wasn't passed
	 * by caller, assume the violator tuple came from there.
	 */
	onfk = (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK);
	if (onfk)
	{
		key_idx = RI_KEYPAIR_FK_IDX;
		if (tupdesc == NULL)
			tupdesc = fk_rel->rd_att;
	}
	else
	{
		key_idx = RI_KEYPAIR_PK_IDX;
		if (tupdesc == NULL)
			tupdesc = pk_rel->rd_att;
	}

	/*
	 * Special case - if there are no keys at all, this is a 'no column'
	 * constraint - no need to try to extract the values, and the message in
	 * this case looks different.
	 */
	if (qkey->nkeypairs == 0)
	{
		ereport(ERROR,
				(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
				 errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
						RelationGetRelationName(fk_rel), constrname),
				 errdetail("No rows were found in \"%s\".",
						   RelationGetRelationName(pk_rel))));
	}

	/* Get printable versions of the keys involved */
	for (idx = 0; idx < qkey->nkeypairs; idx++)
	{
		int			fnum = qkey->keypair[idx][key_idx];
		char	   *name,
				   *val;

		name = SPI_fname(tupdesc, fnum);
		val = SPI_getvalue(violator, tupdesc, fnum);
		if (!val)
			val = "null";

		/*
		 * Go to "..." if name or value doesn't fit in buffer.  We reserve 5
		 * bytes to ensure we can add comma, "...", null.
		 */
		if (strlen(name) >= (key_names + BUFLENGTH - 5) - name_ptr ||
			strlen(val) >= (key_values + BUFLENGTH - 5) - val_ptr)
		{
			sprintf(name_ptr, "...");
			sprintf(val_ptr, "...");
			break;
		}

		name_ptr += sprintf(name_ptr, "%s%s", idx > 0 ? "," : "", name);
		val_ptr += sprintf(val_ptr, "%s%s", idx > 0 ? "," : "", val);
	}

	if (onfk)
		ereport(ERROR,
				(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
				 errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
						RelationGetRelationName(fk_rel), constrname),
				 errdetail("Key (%s)=(%s) is not present in table \"%s\".",
						   key_names, key_values,
						   RelationGetRelationName(pk_rel))));
	else
		ereport(ERROR,
				(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
				 errmsg("update or delete on table \"%s\" violates foreign key constraint \"%s\" on table \"%s\"",
						RelationGetRelationName(pk_rel),
						constrname, RelationGetRelationName(fk_rel)),
			errdetail("Key (%s)=(%s) is still referenced from table \"%s\".",
					  key_names, key_values,
					  RelationGetRelationName(fk_rel))));
}

/* ----------
 * ri_BuildQueryKeyPkCheck -
 *
 *	Build up a new hashtable key for a prepared SPI plan of a
 *	check for PK rows in noaction triggers.
 *
 *		key: output argument, *key is filled in based on the other arguments
 *		riinfo: info from pg_constraint entry
 *		constr_queryno: an internal number of the query inside the proc
 *
 *	At least for MATCH FULL this builds a unique key per plan.
 * ----------
 */
static void
ri_BuildQueryKeyPkCheck(RI_QueryKey *key, const RI_ConstraintInfo *riinfo,
						int32 constr_queryno)
{
	int			i;

	MemSet(key, 0, sizeof(RI_QueryKey));
	key->constr_type = FKCONSTR_MATCH_FULL;
	key->constr_id = riinfo->constraint_id;
	key->constr_queryno = constr_queryno;
	key->fk_relid = InvalidOid;
	key->pk_relid = riinfo->pk_relid;
	key->nkeypairs = riinfo->nkeys;
	for (i = 0; i < riinfo->nkeys; i++)
	{
		key->keypair[i][RI_KEYPAIR_FK_IDX] = 0;
		key->keypair[i][RI_KEYPAIR_PK_IDX] = riinfo->pk_attnums[i];
	}
}


/* ----------
 * ri_NullCheck -
 *
 *	Determine the NULL state of all key values in a tuple
 *
 *	Returns one of RI_KEYS_ALL_NULL, RI_KEYS_NONE_NULL or RI_KEYS_SOME_NULL.
 * ----------
 */
static int
ri_NullCheck(Relation rel, HeapTuple tup, RI_QueryKey *key, int pairidx)
{
	int			i;
	bool		isnull;
	bool		allnull = true;
	bool		nonenull = true;

	for (i = 0; i < key->nkeypairs; i++)
	{
		isnull = false;
		SPI_getbinval(tup, rel->rd_att, key->keypair[i][pairidx], &isnull);
		if (isnull)
			nonenull = false;
		else
			allnull = false;
	}

	if (allnull)
		return RI_KEYS_ALL_NULL;

	if (nonenull)
		return RI_KEYS_NONE_NULL;

	return RI_KEYS_SOME_NULL;
}


/* ----------
 * ri_InitHashTables -
 *
 *	Initialize our internal hash tables for prepared
 *	query plans and comparison operators.
 * ----------
 */
static void
ri_InitHashTables(void)
{
	HASHCTL		ctl;

	memset(&ctl, 0, sizeof(ctl));
	ctl.keysize = sizeof(RI_QueryKey);
	ctl.entrysize = sizeof(RI_QueryHashEntry);
	ctl.hash = tag_hash;
	ri_query_cache = hash_create("RI query cache", RI_INIT_QUERYHASHSIZE,
								 &ctl, HASH_ELEM | HASH_FUNCTION);

	memset(&ctl, 0, sizeof(ctl));
	ctl.keysize = sizeof(RI_CompareKey);
	ctl.entrysize = sizeof(RI_CompareHashEntry);
	ctl.hash = tag_hash;
	ri_compare_cache = hash_create("RI compare cache", RI_INIT_QUERYHASHSIZE,
								   &ctl, HASH_ELEM | HASH_FUNCTION);
}


/* ----------
 * ri_FetchPreparedPlan -
 *
 *	Lookup for a query key in our private hash table of prepared
 *	and saved SPI execution plans. Return the plan if found or NULL.
 * ----------
 */
static SPIPlanPtr
ri_FetchPreparedPlan(RI_QueryKey *key)
{
	RI_QueryHashEntry *entry;

	/*
	 * On the first call initialize the hashtable
	 */
	if (!ri_query_cache)
		ri_InitHashTables();

	/*
	 * Lookup for the key
	 */
	entry = (RI_QueryHashEntry *) hash_search(ri_query_cache,
											  (void *) key,
											  HASH_FIND, NULL);
	if (entry == NULL)
		return NULL;
	return entry->plan;
}


/* ----------
 * ri_HashPreparedPlan -
 *
 *	Add another plan to our private SPI query plan hashtable.
 * ----------
 */
static void
ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan)
{
	RI_QueryHashEntry *entry;
	bool		found;

	/*
	 * On the first call initialize the hashtable
	 */
	if (!ri_query_cache)
		ri_InitHashTables();

	/*
	 * Add the new plan.
	 */
	entry = (RI_QueryHashEntry *) hash_search(ri_query_cache,
											  (void *) key,
											  HASH_ENTER, &found);
	entry->plan = plan;
}


/* ----------
 * ri_KeysEqual -
 *
 *	Check if all key values in OLD and NEW are equal.
 * ----------
 */
static bool
ri_KeysEqual(Relation rel, HeapTuple oldtup, HeapTuple newtup,
			 const RI_ConstraintInfo *riinfo, bool rel_is_pk)
{
	TupleDesc	tupdesc = RelationGetDescr(rel);
	const int16 *attnums;
	const Oid  *eq_oprs;
	int			i;

	if (rel_is_pk)
	{
		attnums = riinfo->pk_attnums;
		eq_oprs = riinfo->pp_eq_oprs;
	}
	else
	{
		attnums = riinfo->fk_attnums;
		eq_oprs = riinfo->ff_eq_oprs;
	}

	for (i = 0; i < riinfo->nkeys; i++)
	{
		Datum		oldvalue;
		Datum		newvalue;
		bool		isnull;

		/*
		 * Get one attribute's oldvalue. If it is NULL - they're not equal.
		 */
		oldvalue = SPI_getbinval(oldtup, tupdesc, attnums[i], &isnull);
		if (isnull)
			return false;

		/*
		 * Get one attribute's newvalue. If it is NULL - they're not equal.
		 */
		newvalue = SPI_getbinval(newtup, tupdesc, attnums[i], &isnull);
		if (isnull)
			return false;

		/*
		 * Compare them with the appropriate equality operator.
		 */
		if (!ri_AttributesEqual(eq_oprs[i], RIAttType(rel, attnums[i]),
								oldvalue, newvalue))
			return false;
	}

	return true;
}


/* ----------
 * ri_AllKeysUnequal -
 *
 *	Check if all key values in OLD and NEW are not equal.
 * ----------
 */
static bool
ri_AllKeysUnequal(Relation rel, HeapTuple oldtup, HeapTuple newtup,
				  const RI_ConstraintInfo *riinfo, bool rel_is_pk)
{
	TupleDesc	tupdesc = RelationGetDescr(rel);
	const int16 *attnums;
	const Oid  *eq_oprs;
	int			i;

	if (rel_is_pk)
	{
		attnums = riinfo->pk_attnums;
		eq_oprs = riinfo->pp_eq_oprs;
	}
	else
	{
		attnums = riinfo->fk_attnums;
		eq_oprs = riinfo->ff_eq_oprs;
	}

	for (i = 0; i < riinfo->nkeys; i++)
	{
		Datum		oldvalue;
		Datum		newvalue;
		bool		isnull;

		/*
		 * Get one attribute's oldvalue. If it is NULL - they're not equal.
		 */
		oldvalue = SPI_getbinval(oldtup, tupdesc, attnums[i], &isnull);
		if (isnull)
			continue;

		/*
		 * Get one attribute's newvalue. If it is NULL - they're not equal.
		 */
		newvalue = SPI_getbinval(newtup, tupdesc, attnums[i], &isnull);
		if (isnull)
			continue;

		/*
		 * Compare them with the appropriate equality operator.
		 */
		if (ri_AttributesEqual(eq_oprs[i], RIAttType(rel, attnums[i]),
							   oldvalue, newvalue))
			return false;		/* found two equal items */
	}

	return true;
}


/* ----------
 * ri_OneKeyEqual -
 *
 *	Check if one key value in OLD and NEW is equal.  Note column is indexed
 *	from zero.
 *
 *	ri_KeysEqual could call this but would run a bit slower.  For
 *	now, let's duplicate the code.
 * ----------
 */
static bool
ri_OneKeyEqual(Relation rel, int column, HeapTuple oldtup, HeapTuple newtup,
			   const RI_ConstraintInfo *riinfo, bool rel_is_pk)
{
	TupleDesc	tupdesc = RelationGetDescr(rel);
	const int16 *attnums;
	const Oid  *eq_oprs;
	Datum		oldvalue;
	Datum		newvalue;
	bool		isnull;

	if (rel_is_pk)
	{
		attnums = riinfo->pk_attnums;
		eq_oprs = riinfo->pp_eq_oprs;
	}
	else
	{
		attnums = riinfo->fk_attnums;
		eq_oprs = riinfo->ff_eq_oprs;
	}

	/*
	 * Get one attribute's oldvalue. If it is NULL - they're not equal.
	 */
	oldvalue = SPI_getbinval(oldtup, tupdesc, attnums[column], &isnull);
	if (isnull)
		return false;

	/*
	 * Get one attribute's newvalue. If it is NULL - they're not equal.
	 */
	newvalue = SPI_getbinval(newtup, tupdesc, attnums[column], &isnull);
	if (isnull)
		return false;

	/*
	 * Compare them with the appropriate equality operator.
	 */
	if (!ri_AttributesEqual(eq_oprs[column], RIAttType(rel, attnums[column]),
							oldvalue, newvalue))
		return false;

	return true;
}

/* ----------
 * ri_AttributesEqual -
 *
 *	Call the appropriate equality comparison operator for two values.
 *
 *	NB: we have already checked that neither value is null.
 * ----------
 */
static bool
ri_AttributesEqual(Oid eq_opr, Oid typeid,
				   Datum oldvalue, Datum newvalue)
{
	RI_CompareHashEntry *entry = ri_HashCompareOp(eq_opr, typeid);

	/* Do we need to cast the values? */
	if (OidIsValid(entry->cast_func_finfo.fn_oid))
	{
		oldvalue = FunctionCall3(&entry->cast_func_finfo,
								 oldvalue,
								 Int32GetDatum(-1),		/* typmod */
								 BoolGetDatum(false));	/* implicit coercion */
		newvalue = FunctionCall3(&entry->cast_func_finfo,
								 newvalue,
								 Int32GetDatum(-1),		/* typmod */
								 BoolGetDatum(false));	/* implicit coercion */
	}

	/* Apply the comparison operator */
	return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
									  oldvalue, newvalue));
}

/* ----------
 * ri_HashCompareOp -
 *
 *	See if we know how to compare two values, and create a new hash entry
 *	if not.
 * ----------
 */
static RI_CompareHashEntry *
ri_HashCompareOp(Oid eq_opr, Oid typeid)
{
	RI_CompareKey key;
	RI_CompareHashEntry *entry;
	bool		found;

	/*
	 * On the first call initialize the hashtable
	 */
	if (!ri_compare_cache)
		ri_InitHashTables();

	/*
	 * Find or create a hash entry.  Note we're assuming RI_CompareKey
	 * contains no struct padding.
	 */
	key.eq_opr = eq_opr;
	key.typeid = typeid;
	entry = (RI_CompareHashEntry *) hash_search(ri_compare_cache,
												(void *) &key,
												HASH_ENTER, &found);
	if (!found)
		entry->valid = false;

	/*
	 * If not already initialized, do so.  Since we'll keep this hash entry
	 * for the life of the backend, put any subsidiary info for the function
	 * cache structs into TopMemoryContext.
	 */
	if (!entry->valid)
	{
		Oid			lefttype,
					righttype,
					castfunc;
		CoercionPathType pathtype;

		/* We always need to know how to call the equality operator */
		fmgr_info_cxt(get_opcode(eq_opr), &entry->eq_opr_finfo,
					  TopMemoryContext);

		/*
		 * If we chose to use a cast from FK to PK type, we may have to apply
		 * the cast function to get to the operator's input type.
		 *
		 * XXX eventually it would be good to support array-coercion cases
		 * here and in ri_AttributesEqual().  At the moment there is no point
		 * because cases involving nonidentical array types will be rejected
		 * at constraint creation time.
		 *
		 * XXX perhaps also consider supporting CoerceViaIO?  No need at the
		 * moment since that will never be generated for implicit coercions.
		 */
		op_input_types(eq_opr, &lefttype, &righttype);
		Assert(lefttype == righttype);
		if (typeid == lefttype)
			castfunc = InvalidOid;		/* simplest case */
		else
		{
			pathtype = find_coercion_pathway(lefttype, typeid,
											 COERCION_IMPLICIT,
											 &castfunc);
			if (pathtype != COERCION_PATH_FUNC &&
				pathtype != COERCION_PATH_RELABELTYPE)
			{
				/* If target is ANYARRAY, assume it's OK, else punt. */
				if (lefttype != ANYARRAYOID)
					elog(ERROR, "no conversion function from %s to %s",
						 format_type_be(typeid),
						 format_type_be(lefttype));
			}
		}
		if (OidIsValid(castfunc))
			fmgr_info_cxt(castfunc, &entry->cast_func_finfo,
						  TopMemoryContext);
		else
			entry->cast_func_finfo.fn_oid = InvalidOid;
		entry->valid = true;
	}

	return entry;
}


/*
 * Given a trigger function OID, determine whether it is an RI trigger,
 * and if so whether it is attached to PK or FK relation.
 */
int
RI_FKey_trigger_type(Oid tgfoid)
{
	switch (tgfoid)
	{
		case F_RI_FKEY_CASCADE_DEL:
		case F_RI_FKEY_CASCADE_UPD:
		case F_RI_FKEY_RESTRICT_DEL:
		case F_RI_FKEY_RESTRICT_UPD:
		case F_RI_FKEY_SETNULL_DEL:
		case F_RI_FKEY_SETNULL_UPD:
		case F_RI_FKEY_SETDEFAULT_DEL:
		case F_RI_FKEY_SETDEFAULT_UPD:
		case F_RI_FKEY_NOACTION_DEL:
		case F_RI_FKEY_NOACTION_UPD:
			return RI_TRIGGER_PK;

		case F_RI_FKEY_CHECK_INS:
		case F_RI_FKEY_CHECK_UPD:
			return RI_TRIGGER_FK;
	}

	return RI_TRIGGER_NONE;
}