text: /*-------------------------------------------------------------------------
   *
   * trigger.c
   *	  PostgreSQL TRIGGERs support code.
   *
   * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * IDENTIFICATION
   *	  src/backend/commands/trigger.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "access/genam.h"
  #include "access/heapam.h"
  #include "access/sysattr.h"
  #include "access/xact.h"
  #include "catalog/catalog.h"
  #include "catalog/dependency.h"
  #include "catalog/indexing.h"
  #include "catalog/objectaccess.h"
  #include "catalog/pg_constraint.h"
  #include "catalog/pg_proc.h"
  #include "catalog/pg_trigger.h"
  #include "catalog/pg_type.h"
  #include "commands/dbcommands.h"
  #include "commands/defrem.h"
  #include "commands/trigger.h"
  #include "executor/executor.h"
  #include "miscadmin.h"
  #include "nodes/bitmapset.h"
  #include "nodes/makefuncs.h"
  #include "optimizer/clauses.h"
  #include "optimizer/var.h"
  #include "parser/parse_clause.h"
  #include "parser/parse_collate.h"
  #include "parser/parse_func.h"
  #include "parser/parse_relation.h"
  #include "parser/parsetree.h"
  #include "pgstat.h"
  #include "rewrite/rewriteManip.h"
  #include "storage/bufmgr.h"
  #include "storage/lmgr.h"
  #include "tcop/utility.h"
  #include "utils/acl.h"
  #include "utils/builtins.h"
  #include "utils/bytea.h"
  #include "utils/fmgroids.h"
  #include "utils/inval.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/rel.h"
  #include "utils/snapmgr.h"
  #include "utils/syscache.h"
  #include "utils/tqual.h"
  
  
  /* GUC variables */
  int			SessionReplicationRole = SESSION_REPLICATION_ROLE_ORIGIN;
  
  /* How many levels deep into trigger execution are we? */
  static int	MyTriggerDepth = 0;
  
  /*
   * Note that this macro also exists in executor/execMain.c.  There does not
   * appear to be any good header to put it into, given the structures that
   * it uses, so we let them be duplicated.  Be sure to update both if one needs
   * to be changed, however.
   */
  #define GetModifiedColumns(relinfo, estate) \
  	(rt_fetch((relinfo)->ri_RangeTableIndex, (estate)->es_range_table)->modifiedCols)
  
  /* Local function prototypes */
  static void ConvertTriggerToFK(CreateTrigStmt *stmt, Oid funcoid);
  static void SetTriggerFlags(TriggerDesc *trigdesc, Trigger *trigger);
  static HeapTuple GetTupleForTrigger(EState *estate,
  				   EPQState *epqstate,
  				   ResultRelInfo *relinfo,
  				   ItemPointer tid,
  				   TupleTableSlot **newSlot);
  static bool TriggerEnabled(EState *estate, ResultRelInfo *relinfo,
  			   Trigger *trigger, TriggerEvent event,
  			   Bitmapset *modifiedCols,
  			   HeapTuple oldtup, HeapTuple newtup);
  static HeapTuple ExecCallTriggerFunc(TriggerData *trigdata,
  					int tgindx,
  					FmgrInfo *finfo,
  					Instrumentation *instr,
  					MemoryContext per_tuple_context);
  static void AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
  					  int event, bool row_trigger,
  					  HeapTuple oldtup, HeapTuple newtup,
  					  List *recheckIndexes, Bitmapset *modifiedCols);
  
  
  /*
   * Create a trigger.  Returns the OID of the created trigger.
   *
   * queryString is the source text of the CREATE TRIGGER command.
   * This must be supplied if a whenClause is specified, else it can be NULL.
   *
   * relOid, if nonzero, is the relation on which the trigger should be
   * created.  If zero, the name provided in the statement will be looked up.
   *
   * refRelOid, if nonzero, is the relation to which the constraint trigger
   * refers.  If zero, the constraint relation name provided in the statement
   * will be looked up as needed.
   *
   * constraintOid, if nonzero, says that this trigger is being created
   * internally to implement that constraint.  A suitable pg_depend entry will
   * be made to link the trigger to that constraint.  constraintOid is zero when
   * executing a user-entered CREATE TRIGGER command.  (For CREATE CONSTRAINT
   * TRIGGER, we build a pg_constraint entry internally.)
   *
   * indexOid, if nonzero, is the OID of an index associated with the constraint.
   * We do nothing with this except store it into pg_trigger.tgconstrindid.
   *
   * If isInternal is true then this is an internally-generated trigger.
   * This argument sets the tgisinternal field of the pg_trigger entry, and
   * if TRUE causes us to modify the given trigger name to ensure uniqueness.
   *
   * When isInternal is not true we require ACL_TRIGGER permissions on the
   * relation, as well as ACL_EXECUTE on the trigger function.  For internal
   * triggers the caller must apply any required permission checks.
   *
   * Note: can return InvalidOid if we decided to not create a trigger at all,
   * but a foreign-key constraint.  This is a kluge for backwards compatibility.
   */
  Oid
  CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
  			  Oid relOid, Oid refRelOid, Oid constraintOid, Oid indexOid,
  			  bool isInternal)
  {
  	int16		tgtype;
  	int			ncolumns;
  	int2	   *columns;
  	int2vector *tgattr;
  	Node	   *whenClause;
  	List	   *whenRtable;
  	char	   *qual;
  	Datum		values[Natts_pg_trigger];
  	bool		nulls[Natts_pg_trigger];
  	Relation	rel;
  	AclResult	aclresult;
  	Relation	tgrel;
  	SysScanDesc tgscan;
  	ScanKeyData key;
  	Relation	pgrel;
  	HeapTuple	tuple;
  	Oid			fargtypes[1];	/* dummy */
  	Oid			funcoid;
  	Oid			funcrettype;
  	Oid			trigoid;
  	char		internaltrigname[NAMEDATALEN];
  	char	   *trigname;
  	Oid			constrrelid = InvalidOid;
  	ObjectAddress myself,
  				referenced;
  
  	if (OidIsValid(relOid))
  		rel = heap_open(relOid, AccessExclusiveLock);
  	else
  		rel = heap_openrv(stmt->relation, AccessExclusiveLock);
  
  	/*
  	 * Triggers must be on tables or views, and there are additional
  	 * relation-type-specific restrictions.
  	 */
  	if (rel->rd_rel->relkind == RELKIND_RELATION)
  	{
  		/* Tables can't have INSTEAD OF triggers */
  		if (stmt->timing != TRIGGER_TYPE_BEFORE &&
  			stmt->timing != TRIGGER_TYPE_AFTER)
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("\"%s\" is a table",
  							RelationGetRelationName(rel)),
  					 errdetail("Tables cannot have INSTEAD OF triggers.")));
  	}
  	else if (rel->rd_rel->relkind == RELKIND_VIEW)
  	{
  		/*
  		 * Views can have INSTEAD OF triggers (which we check below are
  		 * row-level), or statement-level BEFORE/AFTER triggers.
  		 */
  		if (stmt->timing != TRIGGER_TYPE_INSTEAD && stmt->row)
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("\"%s\" is a view",
  							RelationGetRelationName(rel)),
  					 errdetail("Views cannot have row-level BEFORE or AFTER triggers.")));
  		/* Disallow TRUNCATE triggers on VIEWs */
  		if (TRIGGER_FOR_TRUNCATE(stmt->events))
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("\"%s\" is a view",
  							RelationGetRelationName(rel)),
  					 errdetail("Views cannot have TRUNCATE triggers.")));
  	}
  	else
  		ereport(ERROR,
  				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  				 errmsg("\"%s\" is not a table or view",
  						RelationGetRelationName(rel))));
  
  	if (!allowSystemTableMods && IsSystemRelation(rel))
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("permission denied: \"%s\" is a system catalog",
  						RelationGetRelationName(rel))));
  
  	if (stmt->isconstraint)
  	{
  		/*
  		 * We must take a lock on the target relation to protect against
  		 * concurrent drop.  It's not clear that AccessShareLock is strong
  		 * enough, but we certainly need at least that much... otherwise, we
  		 * might end up creating a pg_constraint entry referencing a
  		 * nonexistent table.
  		 */
  		if (OidIsValid(refRelOid))
  		{
  			LockRelationOid(refRelOid, AccessShareLock);
  			constrrelid = refRelOid;
  		}
  		else if (stmt->constrrel != NULL)
  			constrrelid = RangeVarGetRelid(stmt->constrrel, AccessShareLock,
  										   false);
  	}
  
  	/* permission checks */
  	if (!isInternal)
  	{
  		aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
  									  ACL_TRIGGER);
  		if (aclresult != ACLCHECK_OK)
  			aclcheck_error(aclresult, ACL_KIND_CLASS,
  						   RelationGetRelationName(rel));
  
  		if (OidIsValid(constrrelid))
  		{
  			aclresult = pg_class_aclcheck(constrrelid, GetUserId(),
  										  ACL_TRIGGER);
  			if (aclresult != ACLCHECK_OK)
  				aclcheck_error(aclresult, ACL_KIND_CLASS,
  							   get_rel_name(constrrelid));
  		}
  	}
  
  	/* Compute tgtype */
  	TRIGGER_CLEAR_TYPE(tgtype);
  	if (stmt->row)
  		TRIGGER_SETT_ROW(tgtype);
  	tgtype |= stmt->timing;
  	tgtype |= stmt->events;
  
  	/* Disallow ROW-level TRUNCATE triggers */
  	if (TRIGGER_FOR_ROW(tgtype) && TRIGGER_FOR_TRUNCATE(tgtype))
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("TRUNCATE FOR EACH ROW triggers are not supported")));
  
  	/* INSTEAD triggers must be row-level, and can't have WHEN or columns */
  	if (TRIGGER_FOR_INSTEAD(tgtype))
  	{
  		if (!TRIGGER_FOR_ROW(tgtype))
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("INSTEAD OF triggers must be FOR EACH ROW")));
  		if (stmt->whenClause)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("INSTEAD OF triggers cannot have WHEN conditions")));
  		if (stmt->columns != NIL)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("INSTEAD OF triggers cannot have column lists")));
  	}
  
  	/*
  	 * Parse the WHEN clause, if any
  	 */
  	if (stmt->whenClause)
  	{
  		ParseState *pstate;
  		RangeTblEntry *rte;
  		List	   *varList;
  		ListCell   *lc;
  
  		/* Set up a pstate to parse with */
  		pstate = make_parsestate(NULL);
  		pstate->p_sourcetext = queryString;
  
  		/*
  		 * Set up RTEs for OLD and NEW references.
  		 *
  		 * 'OLD' must always have varno equal to 1 and 'NEW' equal to 2.
  		 */
  		rte = addRangeTableEntryForRelation(pstate, rel,
  											makeAlias("old", NIL),
  											false, false);
  		addRTEtoQuery(pstate, rte, false, true, true);
  		rte = addRangeTableEntryForRelation(pstate, rel,
  											makeAlias("new", NIL),
  											false, false);
  		addRTEtoQuery(pstate, rte, false, true, true);
  
  		/* Transform expression.  Copy to be sure we don't modify original */
  		whenClause = transformWhereClause(pstate,
  										  copyObject(stmt->whenClause),
  										  "WHEN");
  		/* we have to fix its collations too */
  		assign_expr_collations(pstate, whenClause);
  
  		/*
  		 * No subplans or aggregates, please
  		 */
  		if (pstate->p_hasSubLinks)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				   errmsg("cannot use subquery in trigger WHEN condition")));
  		if (pstate->p_hasAggs)
  			ereport(ERROR,
  					(errcode(ERRCODE_GROUPING_ERROR),
  					 errmsg("cannot use aggregate function in trigger WHEN condition")));
  		if (pstate->p_hasWindowFuncs)
  			ereport(ERROR,
  					(errcode(ERRCODE_WINDOWING_ERROR),
  			errmsg("cannot use window function in trigger WHEN condition")));
  
  		/*
  		 * Check for disallowed references to OLD/NEW.
  		 *
  		 * NB: pull_var_clause is okay here only because we don't allow
  		 * subselects in WHEN clauses; it would fail to examine the contents
  		 * of subselects.
  		 */
  		varList = pull_var_clause(whenClause,
  								  PVC_REJECT_AGGREGATES,
  								  PVC_REJECT_PLACEHOLDERS);
  		foreach(lc, varList)
  		{
  			Var		   *var = (Var *) lfirst(lc);
  
  			switch (var->varno)
  			{
  				case PRS2_OLD_VARNO:
  					if (!TRIGGER_FOR_ROW(tgtype))
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("statement trigger's WHEN condition cannot reference column values"),
  								 parser_errposition(pstate, var->location)));
  					if (TRIGGER_FOR_INSERT(tgtype))
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("INSERT trigger's WHEN condition cannot reference OLD values"),
  								 parser_errposition(pstate, var->location)));
  					/* system columns are okay here */
  					break;
  				case PRS2_NEW_VARNO:
  					if (!TRIGGER_FOR_ROW(tgtype))
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("statement trigger's WHEN condition cannot reference column values"),
  								 parser_errposition(pstate, var->location)));
  					if (TRIGGER_FOR_DELETE(tgtype))
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("DELETE trigger's WHEN condition cannot reference NEW values"),
  								 parser_errposition(pstate, var->location)));
  					if (var->varattno < 0 && TRIGGER_FOR_BEFORE(tgtype))
  						ereport(ERROR,
  								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  								 errmsg("BEFORE trigger's WHEN condition cannot reference NEW system columns"),
  								 parser_errposition(pstate, var->location)));
  					break;
  				default:
  					/* can't happen without add_missing_from, so just elog */
  					elog(ERROR, "trigger WHEN condition cannot contain references to other relations");
  					break;
  			}
  		}
  
  		/* we'll need the rtable for recordDependencyOnExpr */
  		whenRtable = pstate->p_rtable;
  
  		qual = nodeToString(whenClause);
  
  		free_parsestate(pstate);
  	}
  	else
  	{
  		whenClause = NULL;
  		whenRtable = NIL;
  		qual = NULL;
  	}
  
  	/*
  	 * Find and validate the trigger function.
  	 */
  	funcoid = LookupFuncName(stmt->funcname, 0, fargtypes, false);
  	if (!isInternal)
  	{
  		aclresult = pg_proc_aclcheck(funcoid, GetUserId(), ACL_EXECUTE);
  		if (aclresult != ACLCHECK_OK)
  			aclcheck_error(aclresult, ACL_KIND_PROC,
  						   NameListToString(stmt->funcname));
  	}
  	funcrettype = get_func_rettype(funcoid);
  	if (funcrettype != TRIGGEROID)
  	{
  		/*
  		 * We allow OPAQUE just so we can load old dump files.  When we see a
  		 * trigger function declared OPAQUE, change it to TRIGGER.
  		 */
  		if (funcrettype == OPAQUEOID)
  		{
  			ereport(WARNING,
  					(errmsg("changing return type of function %s from \"opaque\" to \"trigger\"",
  							NameListToString(stmt->funcname))));
  			SetFunctionReturnType(funcoid, TRIGGEROID);
  		}
  		else
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  					 errmsg("function %s must return type \"trigger\"",
  							NameListToString(stmt->funcname))));
  	}
  
  	/*
  	 * If the command is a user-entered CREATE CONSTRAINT TRIGGER command that
  	 * references one of the built-in RI_FKey trigger functions, assume it is
  	 * from a dump of a pre-7.3 foreign key constraint, and take steps to
  	 * convert this legacy representation into a regular foreign key
  	 * constraint.  Ugly, but necessary for loading old dump files.
  	 */
  	if (stmt->isconstraint && !isInternal &&
  		list_length(stmt->args) >= 6 &&
  		(list_length(stmt->args) % 2) == 0 &&
  		RI_FKey_trigger_type(funcoid) != RI_TRIGGER_NONE)
  	{
  		/* Keep lock on target rel until end of xact */
  		heap_close(rel, NoLock);
  
  		ConvertTriggerToFK(stmt, funcoid);
  
  		return InvalidOid;
  	}
  
  	/*
  	 * If it's a user-entered CREATE CONSTRAINT TRIGGER command, make a
  	 * corresponding pg_constraint entry.
  	 */
  	if (stmt->isconstraint && !OidIsValid(constraintOid))
  	{
  		/* Internal callers should have made their own constraints */
  		Assert(!isInternal);
  		constraintOid = CreateConstraintEntry(stmt->trigname,
  											  RelationGetNamespace(rel),
  											  CONSTRAINT_TRIGGER,
  											  stmt->deferrable,
  											  stmt->initdeferred,
  											  true,
  											  RelationGetRelid(rel),
  											  NULL,		/* no conkey */
  											  0,
  											  InvalidOid,		/* no domain */
  											  InvalidOid,		/* no index */
  											  InvalidOid,		/* no foreign key */
  											  NULL,
  											  NULL,
  											  NULL,
  											  NULL,
  											  0,
  											  ' ',
  											  ' ',
  											  ' ',
  											  NULL,		/* no exclusion */
  											  NULL,		/* no check constraint */
  											  NULL,
  											  NULL,
  											  true,		/* islocal */
  											  0,		/* inhcount */
  											  true);	/* isnoinherit */
  	}
  
  	/*
  	 * Generate the trigger's OID now, so that we can use it in the name if
  	 * needed.
  	 */
  	tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
  
  	trigoid = GetNewOid(tgrel);
  
  	/*
  	 * If trigger is internally generated, modify the provided trigger name to
  	 * ensure uniqueness by appending the trigger OID.  (Callers will usually
  	 * supply a simple constant trigger name in these cases.)
  	 */
  	if (isInternal)
  	{
  		snprintf(internaltrigname, sizeof(internaltrigname),
  				 "%s_%u", stmt->trigname, trigoid);
  		trigname = internaltrigname;
  	}
  	else
  	{
  		/* user-defined trigger; use the specified trigger name as-is */
  		trigname = stmt->trigname;
  	}
  
  	/*
  	 * Scan pg_trigger for existing triggers on relation.  We do this only to
  	 * give a nice error message if there's already a trigger of the same
  	 * name.  (The unique index on tgrelid/tgname would complain anyway.) We
  	 * can skip this for internally generated triggers, since the name
  	 * modification above should be sufficient.
  	 *
  	 * NOTE that this is cool only because we have AccessExclusiveLock on the
  	 * relation, so the trigger set won't be changing underneath us.
  	 */
  	if (!isInternal)
  	{
  		ScanKeyInit(&key,
  					Anum_pg_trigger_tgrelid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(RelationGetRelid(rel)));
  		tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
  									SnapshotNow, 1, &key);
  		while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
  		{
  			Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple);
  
  			if (namestrcmp(&(pg_trigger->tgname), trigname) == 0)
  				ereport(ERROR,
  						(errcode(ERRCODE_DUPLICATE_OBJECT),
  				  errmsg("trigger \"%s\" for relation \"%s\" already exists",
  						 trigname, RelationGetRelationName(rel))));
  		}
  		systable_endscan(tgscan);
  	}
  
  	/*
  	 * Build the new pg_trigger tuple.
  	 */
  	memset(nulls, false, sizeof(nulls));
  
  	values[Anum_pg_trigger_tgrelid - 1] = ObjectIdGetDatum(RelationGetRelid(rel));
  	values[Anum_pg_trigger_tgname - 1] = DirectFunctionCall1(namein,
  												  CStringGetDatum(trigname));
  	values[Anum_pg_trigger_tgfoid - 1] = ObjectIdGetDatum(funcoid);
  	values[Anum_pg_trigger_tgtype - 1] = Int16GetDatum(tgtype);
  	values[Anum_pg_trigger_tgenabled - 1] = CharGetDatum(TRIGGER_FIRES_ON_ORIGIN);
  	values[Anum_pg_trigger_tgisinternal - 1] = BoolGetDatum(isInternal);
  	values[Anum_pg_trigger_tgconstrrelid - 1] = ObjectIdGetDatum(constrrelid);
  	values[Anum_pg_trigger_tgconstrindid - 1] = ObjectIdGetDatum(indexOid);
  	values[Anum_pg_trigger_tgconstraint - 1] = ObjectIdGetDatum(constraintOid);
  	values[Anum_pg_trigger_tgdeferrable - 1] = BoolGetDatum(stmt->deferrable);
  	values[Anum_pg_trigger_tginitdeferred - 1] = BoolGetDatum(stmt->initdeferred);
  
  	if (stmt->args)
  	{
  		ListCell   *le;
  		char	   *args;
  		int16		nargs = list_length(stmt->args);
  		int			len = 0;
  
  		foreach(le, stmt->args)
  		{
  			char	   *ar = strVal(lfirst(le));
  
  			len += strlen(ar) + 4;
  			for (; *ar; ar++)
  			{
  				if (*ar == '\\')
  					len++;
  			}
  		}
  		args = (char *) palloc(len + 1);
  		args[0] = '\0';
  		foreach(le, stmt->args)
  		{
  			char	   *s = strVal(lfirst(le));
  			char	   *d = args + strlen(args);
  
  			while (*s)
  			{
  				if (*s == '\\')
  					*d++ = '\\';
  				*d++ = *s++;
  			}
  			strcpy(d, "\\000");
  		}
  		values[Anum_pg_trigger_tgnargs - 1] = Int16GetDatum(nargs);
  		values[Anum_pg_trigger_tgargs - 1] = DirectFunctionCall1(byteain,
  													  CStringGetDatum(args));
  	}
  	else
  	{
  		values[Anum_pg_trigger_tgnargs - 1] = Int16GetDatum(0);
  		values[Anum_pg_trigger_tgargs - 1] = DirectFunctionCall1(byteain,
  														CStringGetDatum(""));
  	}
  
  	/* build column number array if it's a column-specific trigger */
  	ncolumns = list_length(stmt->columns);
  	if (ncolumns == 0)
  		columns = NULL;
  	else
  	{
  		ListCell   *cell;
  		int			i = 0;
  
  		columns = (int2 *) palloc(ncolumns * sizeof(int2));
  		foreach(cell, stmt->columns)
  		{
  			char	   *name = strVal(lfirst(cell));
  			int2		attnum;
  			int			j;
  
  			/* Lookup column name.  System columns are not allowed */
  			attnum = attnameAttNum(rel, name, false);
  			if (attnum == InvalidAttrNumber)
  				ereport(ERROR,
  						(errcode(ERRCODE_UNDEFINED_COLUMN),
  					errmsg("column \"%s\" of relation \"%s\" does not exist",
  						   name, RelationGetRelationName(rel))));
  
  			/* Check for duplicates */
  			for (j = i - 1; j >= 0; j--)
  			{
  				if (columns[j] == attnum)
  					ereport(ERROR,
  							(errcode(ERRCODE_DUPLICATE_COLUMN),
  							 errmsg("column \"%s\" specified more than once",
  									name)));
  			}
  
  			columns[i++] = attnum;
  		}
  	}
  	tgattr = buildint2vector(columns, ncolumns);
  	values[Anum_pg_trigger_tgattr - 1] = PointerGetDatum(tgattr);
  
  	/* set tgqual if trigger has WHEN clause */
  	if (qual)
  		values[Anum_pg_trigger_tgqual - 1] = CStringGetTextDatum(qual);
  	else
  		nulls[Anum_pg_trigger_tgqual - 1] = true;
  
  	tuple = heap_form_tuple(tgrel->rd_att, values, nulls);
  
  	/* force tuple to have the desired OID */
  	HeapTupleSetOid(tuple, trigoid);
  
  	/*
  	 * Insert tuple into pg_trigger.
  	 */
  	simple_heap_insert(tgrel, tuple);
  
  	CatalogUpdateIndexes(tgrel, tuple);
  
  	heap_freetuple(tuple);
  	heap_close(tgrel, RowExclusiveLock);
  
  	pfree(DatumGetPointer(values[Anum_pg_trigger_tgname - 1]));
  	pfree(DatumGetPointer(values[Anum_pg_trigger_tgargs - 1]));
  	pfree(DatumGetPointer(values[Anum_pg_trigger_tgattr - 1]));
  
  	/*
  	 * Update relation's pg_class entry.  Crucial side-effect: other backends
  	 * (and this one too!) are sent SI message to make them rebuild relcache
  	 * entries.
  	 */
  	pgrel = heap_open(RelationRelationId, RowExclusiveLock);
  	tuple = SearchSysCacheCopy1(RELOID,
  								ObjectIdGetDatum(RelationGetRelid(rel)));
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "cache lookup failed for relation %u",
  			 RelationGetRelid(rel));
  
  	((Form_pg_class) GETSTRUCT(tuple))->relhastriggers = true;
  
  	simple_heap_update(pgrel, &tuple->t_self, tuple);
  
  	CatalogUpdateIndexes(pgrel, tuple);
  
  	heap_freetuple(tuple);
  	heap_close(pgrel, RowExclusiveLock);
  
  	/*
  	 * We used to try to update the rel's relcache entry here, but that's
  	 * fairly pointless since it will happen as a byproduct of the upcoming
  	 * CommandCounterIncrement...
  	 */
  
  	/*
  	 * Record dependencies for trigger.  Always place a normal dependency on
  	 * the function.
  	 */
  	myself.classId = TriggerRelationId;
  	myself.objectId = trigoid;
  	myself.objectSubId = 0;
  
  	referenced.classId = ProcedureRelationId;
  	referenced.objectId = funcoid;
  	referenced.objectSubId = 0;
  	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
  
  	if (isInternal && OidIsValid(constraintOid))
  	{
  		/*
  		 * Internally-generated trigger for a constraint, so make it an
  		 * internal dependency of the constraint.  We can skip depending on
  		 * the relation(s), as there'll be an indirect dependency via the
  		 * constraint.
  		 */
  		referenced.classId = ConstraintRelationId;
  		referenced.objectId = constraintOid;
  		referenced.objectSubId = 0;
  		recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL);
  	}
  	else
  	{
  		/*
  		 * User CREATE TRIGGER, so place dependencies.  We make trigger be
  		 * auto-dropped if its relation is dropped or if the FK relation is
  		 * dropped.  (Auto drop is compatible with our pre-7.3 behavior.)
  		 */
  		referenced.classId = RelationRelationId;
  		referenced.objectId = RelationGetRelid(rel);
  		referenced.objectSubId = 0;
  		recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
  		if (OidIsValid(constrrelid))
  		{
  			referenced.classId = RelationRelationId;
  			referenced.objectId = constrrelid;
  			referenced.objectSubId = 0;
  			recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
  		}
  		/* Not possible to have an index dependency in this case */
  		Assert(!OidIsValid(indexOid));
  
  		/*
  		 * If it's a user-specified constraint trigger, make the constraint
  		 * internally dependent on the trigger instead of vice versa.
  		 */
  		if (OidIsValid(constraintOid))
  		{
  			referenced.classId = ConstraintRelationId;
  			referenced.objectId = constraintOid;
  			referenced.objectSubId = 0;
  			recordDependencyOn(&referenced, &myself, DEPENDENCY_INTERNAL);
  		}
  	}
  
  	/* If column-specific trigger, add normal dependencies on columns */
  	if (columns != NULL)
  	{
  		int			i;
  
  		referenced.classId = RelationRelationId;
  		referenced.objectId = RelationGetRelid(rel);
  		for (i = 0; i < ncolumns; i++)
  		{
  			referenced.objectSubId = columns[i];
  			recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
  		}
  	}
  
  	/*
  	 * If it has a WHEN clause, add dependencies on objects mentioned in the
  	 * expression (eg, functions, as well as any columns used).
  	 */
  	if (whenClause != NULL)
  		recordDependencyOnExpr(&myself, whenClause, whenRtable,
  							   DEPENDENCY_NORMAL);
  
  	/* Post creation hook for new trigger */
  	InvokeObjectAccessHook(OAT_POST_CREATE,
  						   TriggerRelationId, trigoid, 0, NULL);
  
  	/* Keep lock on target rel until end of xact */
  	heap_close(rel, NoLock);
  
  	return trigoid;
  }
  
  
  /*
   * Convert legacy (pre-7.3) CREATE CONSTRAINT TRIGGER commands into
   * full-fledged foreign key constraints.
   *
   * The conversion is complex because a pre-7.3 foreign key involved three
   * separate triggers, which were reported separately in dumps.  While the
   * single trigger on the referencing table adds no new information, we need
   * to know the trigger functions of both of the triggers on the referenced
   * table to build the constraint declaration.  Also, due to lack of proper
   * dependency checking pre-7.3, it is possible that the source database had
   * an incomplete set of triggers resulting in an only partially enforced
   * FK constraint.  (This would happen if one of the tables had been dropped
   * and re-created, but only if the DB had been affected by a 7.0 pg_dump bug
   * that caused loss of tgconstrrelid information.)	We choose to translate to
   * an FK constraint only when we've seen all three triggers of a set.  This is
   * implemented by storing unmatched items in a list in TopMemoryContext.
   * We match triggers together by comparing the trigger arguments (which
   * include constraint name, table and column names, so should be good enough).
   */
  typedef struct
  {
  	List	   *args;			/* list of (T_String) Values or NIL */
  	Oid			funcoids[3];	/* OIDs of trigger functions */
  	/* The three function OIDs are stored in the order update, delete, child */
  } OldTriggerInfo;
  
  static void
  ConvertTriggerToFK(CreateTrigStmt *stmt, Oid funcoid)
  {
  	static List *info_list = NIL;
  
  	static const char *const funcdescr[3] = {
  		gettext_noop("Found referenced table's UPDATE trigger."),
  		gettext_noop("Found referenced table's DELETE trigger."),
  		gettext_noop("Found referencing table's trigger.")
  	};
  
  	char	   *constr_name;
  	char	   *fk_table_name;
  	char	   *pk_table_name;
  	char		fk_matchtype = FKCONSTR_MATCH_UNSPECIFIED;
  	List	   *fk_attrs = NIL;
  	List	   *pk_attrs = NIL;
  	StringInfoData buf;
  	int			funcnum;
  	OldTriggerInfo *info = NULL;
  	ListCell   *l;
  	int			i;
  
  	/* Parse out the trigger arguments */
  	constr_name = strVal(linitial(stmt->args));
  	fk_table_name = strVal(lsecond(stmt->args));
  	pk_table_name = strVal(lthird(stmt->args));
  	i = 0;
  	foreach(l, stmt->args)
  	{
  		Value	   *arg = (Value *) lfirst(l);
  
  		i++;
  		if (i < 4)				/* skip constraint and table names */
  			continue;
  		if (i == 4)				/* handle match type */
  		{
  			if (strcmp(strVal(arg), "FULL") == 0)
  				fk_matchtype = FKCONSTR_MATCH_FULL;
  			else
  				fk_matchtype = FKCONSTR_MATCH_UNSPECIFIED;
  			continue;
  		}
  		if (i % 2)
  			fk_attrs = lappend(fk_attrs, arg);
  		else
  			pk_attrs = lappend(pk_attrs, arg);
  	}
  
  	/* Prepare description of constraint for use in messages */
  	initStringInfo(&buf);
  	appendStringInfo(&buf, "FOREIGN KEY %s(",
  					 quote_identifier(fk_table_name));
  	i = 0;
  	foreach(l, fk_attrs)
  	{
  		Value	   *arg = (Value *) lfirst(l);
  
  		if (i++ > 0)
  			appendStringInfoChar(&buf, ',');
  		appendStringInfoString(&buf, quote_identifier(strVal(arg)));
  	}
  	appendStringInfo(&buf, ") REFERENCES %s(",
  					 quote_identifier(pk_table_name));
  	i = 0;
  	foreach(l, pk_attrs)
  	{
  		Value	   *arg = (Value *) lfirst(l);
  
  		if (i++ > 0)
  			appendStringInfoChar(&buf, ',');
  		appendStringInfoString(&buf, quote_identifier(strVal(arg)));
  	}
  	appendStringInfoChar(&buf, ')');
  
  	/* Identify class of trigger --- update, delete, or referencing-table */
  	switch (funcoid)
  	{
  		case F_RI_FKEY_CASCADE_UPD:
  		case F_RI_FKEY_RESTRICT_UPD:
  		case F_RI_FKEY_SETNULL_UPD:
  		case F_RI_FKEY_SETDEFAULT_UPD:
  		case F_RI_FKEY_NOACTION_UPD:
  			funcnum = 0;
  			break;
  
  		case F_RI_FKEY_CASCADE_DEL:
  		case F_RI_FKEY_RESTRICT_DEL:
  		case F_RI_FKEY_SETNULL_DEL:
  		case F_RI_FKEY_SETDEFAULT_DEL:
  		case F_RI_FKEY_NOACTION_DEL:
  			funcnum = 1;
  			break;
  
  		default:
  			funcnum = 2;
  			break;
  	}
  
  	/* See if we have a match to this trigger */
  	foreach(l, info_list)
  	{
  		info = (OldTriggerInfo *) lfirst(l);
  		if (info->funcoids[funcnum] == InvalidOid &&
  			equal(info->args, stmt->args))
  		{
  			info->funcoids[funcnum] = funcoid;
  			break;
  		}
  	}
  
  	if (l == NULL)
  	{
  		/* First trigger of set, so create a new list entry */
  		MemoryContext oldContext;
  
  		ereport(NOTICE,
  		(errmsg("ignoring incomplete trigger group for constraint \"%s\" %s",
  				constr_name, buf.data),
  		 errdetail_internal("%s", _(funcdescr[funcnum]))));
  		oldContext = MemoryContextSwitchTo(TopMemoryContext);
  		info = (OldTriggerInfo *) palloc0(sizeof(OldTriggerInfo));
  		info->args = copyObject(stmt->args);
  		info->funcoids[funcnum] = funcoid;
  		info_list = lappend(info_list, info);
  		MemoryContextSwitchTo(oldContext);
  	}
  	else if (info->funcoids[0] == InvalidOid ||
  			 info->funcoids[1] == InvalidOid ||
  			 info->funcoids[2] == InvalidOid)
  	{
  		/* Second trigger of set */
  		ereport(NOTICE,
  		(errmsg("ignoring incomplete trigger group for constraint \"%s\" %s",
  				constr_name, buf.data),
  		 errdetail_internal("%s", _(funcdescr[funcnum]))));
  	}
  	else
  	{
  		/* OK, we have a set, so make the FK constraint ALTER TABLE cmd */
  		AlterTableStmt *atstmt = makeNode(AlterTableStmt);
  		AlterTableCmd *atcmd = makeNode(AlterTableCmd);
  		Constraint *fkcon = makeNode(Constraint);
  
  		ereport(NOTICE,
  				(errmsg("converting trigger group into constraint \"%s\" %s",
  						constr_name, buf.data),
  				 errdetail_internal("%s", _(funcdescr[funcnum]))));
  		fkcon->contype = CONSTR_FOREIGN;
  		fkcon->location = -1;
  		if (funcnum == 2)
  		{
  			/* This trigger is on the FK table */
  			atstmt->relation = stmt->relation;
  			if (stmt->constrrel)
  				fkcon->pktable = stmt->constrrel;
  			else
  			{
  				/* Work around ancient pg_dump bug that omitted constrrel */
  				fkcon->pktable = makeRangeVar(NULL, pk_table_name, -1);
  			}
  		}
  		else
  		{
  			/* This trigger is on the PK table */
  			fkcon->pktable = stmt->relation;
  			if (stmt->constrrel)
  				atstmt->relation = stmt->constrrel;
  			else
  			{
  				/* Work around ancient pg_dump bug that omitted constrrel */
  				atstmt->relation = makeRangeVar(NULL, fk_table_name, -1);
  			}
  		}
  		atstmt->cmds = list_make1(atcmd);
  		atstmt->relkind = OBJECT_TABLE;
  		atcmd->subtype = AT_AddConstraint;
  		atcmd->def = (Node *) fkcon;
  		if (strcmp(constr_name, "<unnamed>") == 0)
  			fkcon->conname = NULL;
  		else
  			fkcon->conname = constr_name;
  		fkcon->fk_attrs = fk_attrs;
  		fkcon->pk_attrs = pk_attrs;
  		fkcon->fk_matchtype = fk_matchtype;
  		switch (info->funcoids[0])
  		{
  			case F_RI_FKEY_NOACTION_UPD:
  				fkcon->fk_upd_action = FKCONSTR_ACTION_NOACTION;
  				break;
  			case F_RI_FKEY_CASCADE_UPD:
  				fkcon->fk_upd_action = FKCONSTR_ACTION_CASCADE;
  				break;
  			case F_RI_FKEY_RESTRICT_UPD:
  				fkcon->fk_upd_action = FKCONSTR_ACTION_RESTRICT;
  				break;
  			case F_RI_FKEY_SETNULL_UPD:
  				fkcon->fk_upd_action = FKCONSTR_ACTION_SETNULL;
  				break;
  			case F_RI_FKEY_SETDEFAULT_UPD:
  				fkcon->fk_upd_action = FKCONSTR_ACTION_SETDEFAULT;
  				break;
  			default:
  				/* can't get here because of earlier checks */
  				elog(ERROR, "confused about RI update function");
  		}
  		switch (info->funcoids[1])
  		{
  			case F_RI_FKEY_NOACTION_DEL:
  				fkcon->fk_del_action = FKCONSTR_ACTION_NOACTION;
  				break;
  			case F_RI_FKEY_CASCADE_DEL:
  				fkcon->fk_del_action = FKCONSTR_ACTION_CASCADE;
  				break;
  			case F_RI_FKEY_RESTRICT_DEL:
  				fkcon->fk_del_action = FKCONSTR_ACTION_RESTRICT;
  				break;
  			case F_RI_FKEY_SETNULL_DEL:
  				fkcon->fk_del_action = FKCONSTR_ACTION_SETNULL;
  				break;
  			case F_RI_FKEY_SETDEFAULT_DEL:
  				fkcon->fk_del_action = FKCONSTR_ACTION_SETDEFAULT;
  				break;
  			default:
  				/* can't get here because of earlier checks */
  				elog(ERROR, "confused about RI delete function");
  		}
  		fkcon->deferrable = stmt->deferrable;
  		fkcon->initdeferred = stmt->initdeferred;
  		fkcon->skip_validation = false;
  		fkcon->initially_valid = true;
  
  		/* ... and execute it */
  		ProcessUtility((Node *) atstmt,
  					   "(generated ALTER TABLE ADD FOREIGN KEY command)",
  					   NULL, false, None_Receiver, NULL);
  
  		/* Remove the matched item from the list */
  		info_list = list_delete_ptr(info_list, info);
  		pfree(info);
  		/* We leak the copied args ... not worth worrying about */
  	}
  }
  
  /*
   * Guts of trigger deletion.
   */
  void
  RemoveTriggerById(Oid trigOid)
  {
  	Relation	tgrel;
  	SysScanDesc tgscan;
  	ScanKeyData skey[1];
  	HeapTuple	tup;
  	Oid			relid;
  	Relation	rel;
  
  	tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
  
  	/*
  	 * Find the trigger to delete.
  	 */
  	ScanKeyInit(&skey[0],
  				ObjectIdAttributeNumber,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(trigOid));
  
  	tgscan = systable_beginscan(tgrel, TriggerOidIndexId, true,
  								SnapshotNow, 1, skey);
  
  	tup = systable_getnext(tgscan);
  	if (!HeapTupleIsValid(tup))
  		elog(ERROR, "could not find tuple for trigger %u", trigOid);
  
  	/*
  	 * Open and exclusive-lock the relation the trigger belongs to.
  	 */
  	relid = ((Form_pg_trigger) GETSTRUCT(tup))->tgrelid;
  
  	rel = heap_open(relid, AccessExclusiveLock);
  
  	if (rel->rd_rel->relkind != RELKIND_RELATION &&
  		rel->rd_rel->relkind != RELKIND_VIEW)
  		ereport(ERROR,
  				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  				 errmsg("\"%s\" is not a table or view",
  						RelationGetRelationName(rel))));
  
  	if (!allowSystemTableMods && IsSystemRelation(rel))
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("permission denied: \"%s\" is a system catalog",
  						RelationGetRelationName(rel))));
  
  	/*
  	 * Delete the pg_trigger tuple.
  	 */
  	simple_heap_delete(tgrel, &tup->t_self);
  
  	systable_endscan(tgscan);
  	heap_close(tgrel, RowExclusiveLock);
  
  	/*
  	 * We do not bother to try to determine whether any other triggers remain,
  	 * which would be needed in order to decide whether it's safe to clear the
  	 * relation's relhastriggers.  (In any case, there might be a concurrent
  	 * process adding new triggers.)  Instead, just force a relcache inval to
  	 * make other backends (and this one too!) rebuild their relcache entries.
  	 * There's no great harm in leaving relhastriggers true even if there are
  	 * no triggers left.
  	 */
  	CacheInvalidateRelcache(rel);
  
  	/* Keep lock on trigger's rel until end of xact */
  	heap_close(rel, NoLock);
  }
  
  /*
   * get_trigger_oid - Look up a trigger by name to find its OID.
   *
   * If missing_ok is false, throw an error if trigger not found.  If
   * true, just return InvalidOid.
   */
  Oid
  get_trigger_oid(Oid relid, const char *trigname, bool missing_ok)
  {
  	Relation	tgrel;
  	ScanKeyData skey[2];
  	SysScanDesc tgscan;
  	HeapTuple	tup;
  	Oid			oid;
  
  	/*
  	 * Find the trigger, verify permissions, set up object address
  	 */
  	tgrel = heap_open(TriggerRelationId, AccessShareLock);
  
  	ScanKeyInit(&skey[0],
  				Anum_pg_trigger_tgrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  	ScanKeyInit(&skey[1],
  				Anum_pg_trigger_tgname,
  				BTEqualStrategyNumber, F_NAMEEQ,
  				CStringGetDatum(trigname));
  
  	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
  								SnapshotNow, 2, skey);
  
  	tup = systable_getnext(tgscan);
  
  	if (!HeapTupleIsValid(tup))
  	{
  		if (!missing_ok)
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_OBJECT),
  					 errmsg("trigger \"%s\" for table \"%s\" does not exist",
  							trigname, get_rel_name(relid))));
  		oid = InvalidOid;
  	}
  	else
  	{
  		oid = HeapTupleGetOid(tup);
  	}
  
  	systable_endscan(tgscan);
  	heap_close(tgrel, AccessShareLock);
  	return oid;
  }
  
  /*
   * Perform permissions and integrity checks before acquiring a relation lock.
   */
  static void
  RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
  								 void *arg)
  {
  	HeapTuple	tuple;
  	Form_pg_class form;
  
  	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
  	if (!HeapTupleIsValid(tuple))
  		return;					/* concurrently dropped */
  	form = (Form_pg_class) GETSTRUCT(tuple);
  
  	/* only tables and views can have triggers */
  	if (form->relkind != RELKIND_RELATION && form->relkind != RELKIND_VIEW)
  		ereport(ERROR,
  				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  				 errmsg("\"%s\" is not a table or view", rv->relname)));
  
  	/* you must own the table to rename one of its triggers */
  	if (!pg_class_ownercheck(relid, GetUserId()))
  		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS, rv->relname);
  	if (!allowSystemTableMods && IsSystemClass(form))
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("permission denied: \"%s\" is a system catalog",
  						rv->relname)));
  
  	ReleaseSysCache(tuple);
  }
  
  /*
   *		renametrig		- changes the name of a trigger on a relation
   *
   *		trigger name is changed in trigger catalog.
   *		No record of the previous name is kept.
   *
   *		get proper relrelation from relation catalog (if not arg)
   *		scan trigger catalog
   *				for name conflict (within rel)
   *				for original trigger (if not arg)
   *		modify tgname in trigger tuple
   *		update row in catalog
   */
  void
  renametrig(RenameStmt *stmt)
  {
  	Relation	targetrel;
  	Relation	tgrel;
  	HeapTuple	tuple;
  	SysScanDesc tgscan;
  	ScanKeyData key[2];
  	Oid			relid;
  
  	/*
  	 * Look up name, check permissions, and acquire lock (which we will NOT
  	 * release until end of transaction).
  	 */
  	relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
  									 false, false,
  									 RangeVarCallbackForRenameTrigger,
  									 NULL);
  
  	/* Have lock already, so just need to build relcache entry. */
  	targetrel = relation_open(relid, NoLock);
  
  	/*
  	 * Scan pg_trigger twice for existing triggers on relation.  We do this in
  	 * order to ensure a trigger does not exist with newname (The unique index
  	 * on tgrelid/tgname would complain anyway) and to ensure a trigger does
  	 * exist with oldname.
  	 *
  	 * NOTE that this is cool only because we have AccessExclusiveLock on the
  	 * relation, so the trigger set won't be changing underneath us.
  	 */
  	tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
  
  	/*
  	 * First pass -- look for name conflict
  	 */
  	ScanKeyInit(&key[0],
  				Anum_pg_trigger_tgrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  	ScanKeyInit(&key[1],
  				Anum_pg_trigger_tgname,
  				BTEqualStrategyNumber, F_NAMEEQ,
  				PointerGetDatum(stmt->newname));
  	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
  								SnapshotNow, 2, key);
  	if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
  		ereport(ERROR,
  				(errcode(ERRCODE_DUPLICATE_OBJECT),
  				 errmsg("trigger \"%s\" for relation \"%s\" already exists",
  						stmt->newname, RelationGetRelationName(targetrel))));
  	systable_endscan(tgscan);
  
  	/*
  	 * Second pass -- look for trigger existing with oldname and update
  	 */
  	ScanKeyInit(&key[0],
  				Anum_pg_trigger_tgrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  	ScanKeyInit(&key[1],
  				Anum_pg_trigger_tgname,
  				BTEqualStrategyNumber, F_NAMEEQ,
  				PointerGetDatum(stmt->subname));
  	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
  								SnapshotNow, 2, key);
  	if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
  	{
  		/*
  		 * Update pg_trigger tuple with new tgname.
  		 */
  		tuple = heap_copytuple(tuple);	/* need a modifiable copy */
  
  		namestrcpy(&((Form_pg_trigger) GETSTRUCT(tuple))->tgname,
  				   stmt->newname);
  
  		simple_heap_update(tgrel, &tuple->t_self, tuple);
  
  		/* keep system catalog indexes current */
  		CatalogUpdateIndexes(tgrel, tuple);
  
  		/*
  		 * Invalidate relation's relcache entry so that other backends (and
  		 * this one too!) are sent SI message to make them rebuild relcache
  		 * entries.  (Ideally this should happen automatically...)
  		 */
  		CacheInvalidateRelcache(targetrel);
  	}
  	else
  	{
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  				 errmsg("trigger \"%s\" for table \"%s\" does not exist",
  						stmt->subname, RelationGetRelationName(targetrel))));
  	}
  
  	systable_endscan(tgscan);
  
  	heap_close(tgrel, RowExclusiveLock);
  
  	/*
  	 * Close rel, but keep exclusive lock!
  	 */
  	relation_close(targetrel, NoLock);
  }
  
  
  /*
   * EnableDisableTrigger()
   *
   *	Called by ALTER TABLE ENABLE/DISABLE [ REPLICA | ALWAYS ] TRIGGER
   *	to change 'tgenabled' field for the specified trigger(s)
   *
   * rel: relation to process (caller must hold suitable lock on it)
   * tgname: trigger to process, or NULL to scan all triggers
   * fires_when: new value for tgenabled field. In addition to generic
   *			   enablement/disablement, this also defines when the trigger
   *			   should be fired in session replication roles.
   * skip_system: if true, skip "system" triggers (constraint triggers)
   *
   * Caller should have checked permissions for the table; here we also
   * enforce that superuser privilege is required to alter the state of
   * system triggers
   */
  void
  EnableDisableTrigger(Relation rel, const char *tgname,
  					 char fires_when, bool skip_system)
  {
  	Relation	tgrel;
  	int			nkeys;
  	ScanKeyData keys[2];
  	SysScanDesc tgscan;
  	HeapTuple	tuple;
  	bool		found;
  	bool		changed;
  
  	/* Scan the relevant entries in pg_triggers */
  	tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
  
  	ScanKeyInit(&keys[0],
  				Anum_pg_trigger_tgrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(rel)));
  	if (tgname)
  	{
  		ScanKeyInit(&keys[1],
  					Anum_pg_trigger_tgname,
  					BTEqualStrategyNumber, F_NAMEEQ,
  					CStringGetDatum(tgname));
  		nkeys = 2;
  	}
  	else
  		nkeys = 1;
  
  	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
  								SnapshotNow, nkeys, keys);
  
  	found = changed = false;
  
  	while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
  	{
  		Form_pg_trigger oldtrig = (Form_pg_trigger) GETSTRUCT(tuple);
  
  		if (oldtrig->tgisinternal)
  		{
  			/* system trigger ... ok to process? */
  			if (skip_system)
  				continue;
  			if (!superuser())
  				ereport(ERROR,
  						(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  					  errmsg("permission denied: \"%s\" is a system trigger",
  							 NameStr(oldtrig->tgname))));
  		}
  
  		found = true;
  
  		if (oldtrig->tgenabled != fires_when)
  		{
  			/* need to change this one ... make a copy to scribble on */
  			HeapTuple	newtup = heap_copytuple(tuple);
  			Form_pg_trigger newtrig = (Form_pg_trigger) GETSTRUCT(newtup);
  
  			newtrig->tgenabled = fires_when;
  
  			simple_heap_update(tgrel, &newtup->t_self, newtup);
  
  			/* Keep catalog indexes current */
  			CatalogUpdateIndexes(tgrel, newtup);
  
  			heap_freetuple(newtup);
  
  			changed = true;
  		}
  	}
  
  	systable_endscan(tgscan);
  
  	heap_close(tgrel, RowExclusiveLock);
  
  	if (tgname && !found)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  				 errmsg("trigger \"%s\" for table \"%s\" does not exist",
  						tgname, RelationGetRelationName(rel))));
  
  	/*
  	 * If we changed anything, broadcast a SI inval message to force each
  	 * backend (including our own!) to rebuild relation's relcache entry.
  	 * Otherwise they will fail to apply the change promptly.
  	 */
  	if (changed)
  		CacheInvalidateRelcache(rel);
  }
  
  
  /*
   * Build trigger data to attach to the given relcache entry.
   *
   * Note that trigger data attached to a relcache entry must be stored in
   * CacheMemoryContext to ensure it survives as long as the relcache entry.
   * But we should be running in a less long-lived working context.  To avoid
   * leaking cache memory if this routine fails partway through, we build a
   * temporary TriggerDesc in working memory and then copy the completed
   * structure into cache memory.
   */
  void
  RelationBuildTriggers(Relation relation)
  {
  	TriggerDesc *trigdesc;
  	int			numtrigs;
  	int			maxtrigs;
  	Trigger    *triggers;
  	Relation	tgrel;
  	ScanKeyData skey;
  	SysScanDesc tgscan;
  	HeapTuple	htup;
  	MemoryContext oldContext;
  	int			i;
  
  	/*
  	 * Allocate a working array to hold the triggers (the array is extended if
  	 * necessary)
  	 */
  	maxtrigs = 16;
  	triggers = (Trigger *) palloc(maxtrigs * sizeof(Trigger));
  	numtrigs = 0;
  
  	/*
  	 * Note: since we scan the triggers using TriggerRelidNameIndexId, we will
  	 * be reading the triggers in name order, except possibly during
  	 * emergency-recovery operations (ie, IgnoreSystemIndexes). This in turn
  	 * ensures that triggers will be fired in name order.
  	 */
  	ScanKeyInit(&skey,
  				Anum_pg_trigger_tgrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  
  	tgrel = heap_open(TriggerRelationId, AccessShareLock);
  	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
  								SnapshotNow, 1, &skey);
  
  	while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
  	{
  		Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);
  		Trigger    *build;
  		Datum		datum;
  		bool		isnull;
  
  		if (numtrigs >= maxtrigs)
  		{
  			maxtrigs *= 2;
  			triggers = (Trigger *) repalloc(triggers, maxtrigs * sizeof(Trigger));
  		}
  		build = &(triggers[numtrigs]);
  
  		build->tgoid = HeapTupleGetOid(htup);
  		build->tgname = DatumGetCString(DirectFunctionCall1(nameout,
  										 NameGetDatum(&pg_trigger->tgname)));
  		build->tgfoid = pg_trigger->tgfoid;
  		build->tgtype = pg_trigger->tgtype;
  		build->tgenabled = pg_trigger->tgenabled;
  		build->tgisinternal = pg_trigger->tgisinternal;
  		build->tgconstrrelid = pg_trigger->tgconstrrelid;
  		build->tgconstrindid = pg_trigger->tgconstrindid;
  		build->tgconstraint = pg_trigger->tgconstraint;
  		build->tgdeferrable = pg_trigger->tgdeferrable;
  		build->tginitdeferred = pg_trigger->tginitdeferred;
  		build->tgnargs = pg_trigger->tgnargs;
  		/* tgattr is first var-width field, so OK to access directly */
  		build->tgnattr = pg_trigger->tgattr.dim1;
  		if (build->tgnattr > 0)
  		{
  			build->tgattr = (int2 *) palloc(build->tgnattr * sizeof(int2));
  			memcpy(build->tgattr, &(pg_trigger->tgattr.values),
  				   build->tgnattr * sizeof(int2));
  		}
  		else
  			build->tgattr = NULL;
  		if (build->tgnargs > 0)
  		{
  			bytea	   *val;
  			char	   *p;
  
  			val = DatumGetByteaP(fastgetattr(htup,
  											 Anum_pg_trigger_tgargs,
  											 tgrel->rd_att, &isnull));
  			if (isnull)
  				elog(ERROR, "tgargs is null in trigger for relation \"%s\"",
  					 RelationGetRelationName(relation));
  			p = (char *) VARDATA(val);
  			build->tgargs = (char **) palloc(build->tgnargs * sizeof(char *));
  			for (i = 0; i < build->tgnargs; i++)
  			{
  				build->tgargs[i] = pstrdup(p);
  				p += strlen(p) + 1;
  			}
  		}
  		else
  			build->tgargs = NULL;
  		datum = fastgetattr(htup, Anum_pg_trigger_tgqual,
  							tgrel->rd_att, &isnull);
  		if (!isnull)
  			build->tgqual = TextDatumGetCString(datum);
  		else
  			build->tgqual = NULL;
  
  		numtrigs++;
  	}
  
  	systable_endscan(tgscan);
  	heap_close(tgrel, AccessShareLock);
  
  	/* There might not be any triggers */
  	if (numtrigs == 0)
  	{
  		pfree(triggers);
  		return;
  	}
  
  	/* Build trigdesc */
  	trigdesc = (TriggerDesc *) palloc0(sizeof(TriggerDesc));
  	trigdesc->triggers = triggers;
  	trigdesc->numtriggers = numtrigs;
  	for (i = 0; i < numtrigs; i++)
  		SetTriggerFlags(trigdesc, &(triggers[i]));
  
  	/* Copy completed trigdesc into cache storage */
  	oldContext = MemoryContextSwitchTo(CacheMemoryContext);
  	relation->trigdesc = CopyTriggerDesc(trigdesc);
  	MemoryContextSwitchTo(oldContext);
  
  	/* Release working memory */
  	FreeTriggerDesc(trigdesc);
  }
  
  /*
   * Update the TriggerDesc's hint flags to include the specified trigger
   */
  static void
  SetTriggerFlags(TriggerDesc *trigdesc, Trigger *trigger)
  {
  	int16		tgtype = trigger->tgtype;
  
  	trigdesc->trig_insert_before_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_INSERT);
  	trigdesc->trig_insert_after_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_AFTER, TRIGGER_TYPE_INSERT);
  	trigdesc->trig_insert_instead_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_INSTEAD, TRIGGER_TYPE_INSERT);
  	trigdesc->trig_insert_before_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_INSERT);
  	trigdesc->trig_insert_after_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_AFTER, TRIGGER_TYPE_INSERT);
  	trigdesc->trig_update_before_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_UPDATE);
  	trigdesc->trig_update_after_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_AFTER, TRIGGER_TYPE_UPDATE);
  	trigdesc->trig_update_instead_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_INSTEAD, TRIGGER_TYPE_UPDATE);
  	trigdesc->trig_update_before_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_UPDATE);
  	trigdesc->trig_update_after_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_AFTER, TRIGGER_TYPE_UPDATE);
  	trigdesc->trig_delete_before_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_DELETE);
  	trigdesc->trig_delete_after_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_AFTER, TRIGGER_TYPE_DELETE);
  	trigdesc->trig_delete_instead_row |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
  							 TRIGGER_TYPE_INSTEAD, TRIGGER_TYPE_DELETE);
  	trigdesc->trig_delete_before_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_DELETE);
  	trigdesc->trig_delete_after_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_AFTER, TRIGGER_TYPE_DELETE);
  	/* there are no row-level truncate triggers */
  	trigdesc->trig_truncate_before_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_TRUNCATE);
  	trigdesc->trig_truncate_after_statement |=
  		TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
  							 TRIGGER_TYPE_AFTER, TRIGGER_TYPE_TRUNCATE);
  }
  
  /*
   * Copy a TriggerDesc data structure.
   *
   * The copy is allocated in the current memory context.
   */
  TriggerDesc *
  CopyTriggerDesc(TriggerDesc *trigdesc)
  {
  	TriggerDesc *newdesc;
  	Trigger    *trigger;
  	int			i;
  
  	if (trigdesc == NULL || trigdesc->numtriggers <= 0)
  		return NULL;
  
  	newdesc = (TriggerDesc *) palloc(sizeof(TriggerDesc));
  	memcpy(newdesc, trigdesc, sizeof(TriggerDesc));
  
  	trigger = (Trigger *) palloc(trigdesc->numtriggers * sizeof(Trigger));
  	memcpy(trigger, trigdesc->triggers,
  		   trigdesc->numtriggers * sizeof(Trigger));
  	newdesc->triggers = trigger;
  
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		trigger->tgname = pstrdup(trigger->tgname);
  		if (trigger->tgnattr > 0)
  		{
  			int2	   *newattr;
  
  			newattr = (int2 *) palloc(trigger->tgnattr * sizeof(int2));
  			memcpy(newattr, trigger->tgattr,
  				   trigger->tgnattr * sizeof(int2));
  			trigger->tgattr = newattr;
  		}
  		if (trigger->tgnargs > 0)
  		{
  			char	  **newargs;
  			int16		j;
  
  			newargs = (char **) palloc(trigger->tgnargs * sizeof(char *));
  			for (j = 0; j < trigger->tgnargs; j++)
  				newargs[j] = pstrdup(trigger->tgargs[j]);
  			trigger->tgargs = newargs;
  		}
  		if (trigger->tgqual)
  			trigger->tgqual = pstrdup(trigger->tgqual);
  		trigger++;
  	}
  
  	return newdesc;
  }
  
  /*
   * Free a TriggerDesc data structure.
   */
  void
  FreeTriggerDesc(TriggerDesc *trigdesc)
  {
  	Trigger    *trigger;
  	int			i;
  
  	if (trigdesc == NULL)
  		return;
  
  	trigger = trigdesc->triggers;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		pfree(trigger->tgname);
  		if (trigger->tgnattr > 0)
  			pfree(trigger->tgattr);
  		if (trigger->tgnargs > 0)
  		{
  			while (--(trigger->tgnargs) >= 0)
  				pfree(trigger->tgargs[trigger->tgnargs]);
  			pfree(trigger->tgargs);
  		}
  		if (trigger->tgqual)
  			pfree(trigger->tgqual);
  		trigger++;
  	}
  	pfree(trigdesc->triggers);
  	pfree(trigdesc);
  }
  
  /*
   * Compare two TriggerDesc structures for logical equality.
   */
  #ifdef NOT_USED
  bool
  equalTriggerDescs(TriggerDesc *trigdesc1, TriggerDesc *trigdesc2)
  {
  	int			i,
  				j;
  
  	/*
  	 * We need not examine the hint flags, just the trigger array itself; if
  	 * we have the same triggers with the same types, the flags should match.
  	 *
  	 * As of 7.3 we assume trigger set ordering is significant in the
  	 * comparison; so we just compare corresponding slots of the two sets.
  	 *
  	 * Note: comparing the stringToNode forms of the WHEN clauses means that
  	 * parse column locations will affect the result.  This is okay as long as
  	 * this function is only used for detecting exact equality, as for example
  	 * in checking for staleness of a cache entry.
  	 */
  	if (trigdesc1 != NULL)
  	{
  		if (trigdesc2 == NULL)
  			return false;
  		if (trigdesc1->numtriggers != trigdesc2->numtriggers)
  			return false;
  		for (i = 0; i < trigdesc1->numtriggers; i++)
  		{
  			Trigger    *trig1 = trigdesc1->triggers + i;
  			Trigger    *trig2 = trigdesc2->triggers + i;
  
  			if (trig1->tgoid != trig2->tgoid)
  				return false;
  			if (strcmp(trig1->tgname, trig2->tgname) != 0)
  				return false;
  			if (trig1->tgfoid != trig2->tgfoid)
  				return false;
  			if (trig1->tgtype != trig2->tgtype)
  				return false;
  			if (trig1->tgenabled != trig2->tgenabled)
  				return false;
  			if (trig1->tgisinternal != trig2->tgisinternal)
  				return false;
  			if (trig1->tgconstrrelid != trig2->tgconstrrelid)
  				return false;
  			if (trig1->tgconstrindid != trig2->tgconstrindid)
  				return false;
  			if (trig1->tgconstraint != trig2->tgconstraint)
  				return false;
  			if (trig1->tgdeferrable != trig2->tgdeferrable)
  				return false;
  			if (trig1->tginitdeferred != trig2->tginitdeferred)
  				return false;
  			if (trig1->tgnargs != trig2->tgnargs)
  				return false;
  			if (trig1->tgnattr != trig2->tgnattr)
  				return false;
  			if (trig1->tgnattr > 0 &&
  				memcmp(trig1->tgattr, trig2->tgattr,
  					   trig1->tgnattr * sizeof(int2)) != 0)
  				return false;
  			for (j = 0; j < trig1->tgnargs; j++)
  				if (strcmp(trig1->tgargs[j], trig2->tgargs[j]) != 0)
  					return false;
  			if (trig1->tgqual == NULL && trig2->tgqual == NULL)
  				 /* ok */ ;
  			else if (trig1->tgqual == NULL || trig2->tgqual == NULL)
  				return false;
  			else if (strcmp(trig1->tgqual, trig2->tgqual) != 0)
  				return false;
  		}
  	}
  	else if (trigdesc2 != NULL)
  		return false;
  	return true;
  }
  #endif   /* NOT_USED */
  
  /*
   * Call a trigger function.
   *
   *		trigdata: trigger descriptor.
   *		tgindx: trigger's index in finfo and instr arrays.
   *		finfo: array of cached trigger function call information.
   *		instr: optional array of EXPLAIN ANALYZE instrumentation state.
   *		per_tuple_context: memory context to execute the function in.
   *
   * Returns the tuple (or NULL) as returned by the function.
   */
  static HeapTuple
  ExecCallTriggerFunc(TriggerData *trigdata,
  					int tgindx,
  					FmgrInfo *finfo,
  					Instrumentation *instr,
  					MemoryContext per_tuple_context)
  {
  	FunctionCallInfoData fcinfo;
  	PgStat_FunctionCallUsage fcusage;
  	Datum		result;
  	MemoryContext oldContext;
  
  	finfo += tgindx;
  
  	/*
  	 * We cache fmgr lookup info, to avoid making the lookup again on each
  	 * call.
  	 */
  	if (finfo->fn_oid == InvalidOid)
  		fmgr_info(trigdata->tg_trigger->tgfoid, finfo);
  
  	Assert(finfo->fn_oid == trigdata->tg_trigger->tgfoid);
  
  	/*
  	 * If doing EXPLAIN ANALYZE, start charging time to this trigger.
  	 */
  	if (instr)
  		InstrStartNode(instr + tgindx);
  
  	/*
  	 * Do the function evaluation in the per-tuple memory context, so that
  	 * leaked memory will be reclaimed once per tuple. Note in particular that
  	 * any new tuple created by the trigger function will live till the end of
  	 * the tuple cycle.
  	 */
  	oldContext = MemoryContextSwitchTo(per_tuple_context);
  
  	/*
  	 * Call the function, passing no arguments but setting a context.
  	 */
  	InitFunctionCallInfoData(fcinfo, finfo, 0,
  							 InvalidOid, (Node *) trigdata, NULL);
  
  	pgstat_init_function_usage(&fcinfo, &fcusage);
  
  	MyTriggerDepth++;
  	PG_TRY();
  	{
  		result = FunctionCallInvoke(&fcinfo);
  	}
  	PG_CATCH();
  	{
  		MyTriggerDepth--;
  		PG_RE_THROW();
  	}
  	PG_END_TRY();
  	MyTriggerDepth--;
  
  	pgstat_end_function_usage(&fcusage, true);
  
  	MemoryContextSwitchTo(oldContext);
  
  	/*
  	 * Trigger protocol allows function to return a null pointer, but NOT to
  	 * set the isnull result flag.
  	 */
  	if (fcinfo.isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
  				 errmsg("trigger function %u returned null value",
  						fcinfo.flinfo->fn_oid)));
  
  	/*
  	 * If doing EXPLAIN ANALYZE, stop charging time to this trigger, and count
  	 * one "tuple returned" (really the number of firings).
  	 */
  	if (instr)
  		InstrStopNode(instr + tgindx, 1);
  
  	return (HeapTuple) DatumGetPointer(result);
  }
  
  void
  ExecBSInsertTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc;
  	int			i;
  	TriggerData LocTriggerData;
  
  	trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc == NULL)
  		return;
  	if (!trigdesc->trig_insert_before_statement)
  		return;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
  		TRIGGER_EVENT_BEFORE;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_trigtuple = NULL;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  		HeapTuple	newtuple;
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_STATEMENT,
  								  TRIGGER_TYPE_BEFORE,
  								  TRIGGER_TYPE_INSERT))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, NULL, NULL))
  			continue;
  
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  
  		if (newtuple)
  			ereport(ERROR,
  					(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
  				  errmsg("BEFORE STATEMENT trigger cannot return a value")));
  	}
  }
  
  void
  ExecASInsertTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc && trigdesc->trig_insert_after_statement)
  		AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_INSERT,
  							  false, NULL, NULL, NIL, NULL);
  }
  
  TupleTableSlot *
  ExecBRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
  					 TupleTableSlot *slot)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  	HeapTuple	slottuple = ExecMaterializeSlot(slot);
  	HeapTuple	newtuple = slottuple;
  	HeapTuple	oldtuple;
  	TriggerData LocTriggerData;
  	int			i;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
  		TRIGGER_EVENT_ROW |
  		TRIGGER_EVENT_BEFORE;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_ROW,
  								  TRIGGER_TYPE_BEFORE,
  								  TRIGGER_TYPE_INSERT))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, NULL, newtuple))
  			continue;
  
  		LocTriggerData.tg_trigtuple = oldtuple = newtuple;
  		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  		if (oldtuple != newtuple && oldtuple != slottuple)
  			heap_freetuple(oldtuple);
  		if (newtuple == NULL)
  			return NULL;		/* "do nothing" */
  	}
  
  	if (newtuple != slottuple)
  	{
  		/*
  		 * Return the modified tuple using the es_trig_tuple_slot.  We assume
  		 * the tuple was allocated in per-tuple memory context, and therefore
  		 * will go away by itself. The tuple table slot should not try to
  		 * clear it.
  		 */
  		TupleTableSlot *newslot = estate->es_trig_tuple_slot;
  		TupleDesc	tupdesc = RelationGetDescr(relinfo->ri_RelationDesc);
  
  		if (newslot->tts_tupleDescriptor != tupdesc)
  			ExecSetSlotDescriptor(newslot, tupdesc);
  		ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
  		slot = newslot;
  	}
  	return slot;
  }
  
  void
  ExecARInsertTriggers(EState *estate, ResultRelInfo *relinfo,
  					 HeapTuple trigtuple, List *recheckIndexes)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc && trigdesc->trig_insert_after_row)
  		AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_INSERT,
  							  true, NULL, trigtuple, recheckIndexes, NULL);
  }
  
  TupleTableSlot *
  ExecIRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
  					 TupleTableSlot *slot)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  	HeapTuple	slottuple = ExecMaterializeSlot(slot);
  	HeapTuple	newtuple = slottuple;
  	HeapTuple	oldtuple;
  	TriggerData LocTriggerData;
  	int			i;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
  		TRIGGER_EVENT_ROW |
  		TRIGGER_EVENT_INSTEAD;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_ROW,
  								  TRIGGER_TYPE_INSTEAD,
  								  TRIGGER_TYPE_INSERT))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, NULL, newtuple))
  			continue;
  
  		LocTriggerData.tg_trigtuple = oldtuple = newtuple;
  		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  		if (oldtuple != newtuple && oldtuple != slottuple)
  			heap_freetuple(oldtuple);
  		if (newtuple == NULL)
  			return NULL;		/* "do nothing" */
  	}
  
  	if (newtuple != slottuple)
  	{
  		/*
  		 * Return the modified tuple using the es_trig_tuple_slot.  We assume
  		 * the tuple was allocated in per-tuple memory context, and therefore
  		 * will go away by itself. The tuple table slot should not try to
  		 * clear it.
  		 */
  		TupleTableSlot *newslot = estate->es_trig_tuple_slot;
  		TupleDesc	tupdesc = RelationGetDescr(relinfo->ri_RelationDesc);
  
  		if (newslot->tts_tupleDescriptor != tupdesc)
  			ExecSetSlotDescriptor(newslot, tupdesc);
  		ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
  		slot = newslot;
  	}
  	return slot;
  }
  
  void
  ExecBSDeleteTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc;
  	int			i;
  	TriggerData LocTriggerData;
  
  	trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc == NULL)
  		return;
  	if (!trigdesc->trig_delete_before_statement)
  		return;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
  		TRIGGER_EVENT_BEFORE;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_trigtuple = NULL;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  		HeapTuple	newtuple;
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_STATEMENT,
  								  TRIGGER_TYPE_BEFORE,
  								  TRIGGER_TYPE_DELETE))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, NULL, NULL))
  			continue;
  
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  
  		if (newtuple)
  			ereport(ERROR,
  					(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
  				  errmsg("BEFORE STATEMENT trigger cannot return a value")));
  	}
  }
  
  void
  ExecASDeleteTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc && trigdesc->trig_delete_after_statement)
  		AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_DELETE,
  							  false, NULL, NULL, NIL, NULL);
  }
  
  bool
  ExecBRDeleteTriggers(EState *estate, EPQState *epqstate,
  					 ResultRelInfo *relinfo,
  					 ItemPointer tupleid)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  	bool		result = true;
  	TriggerData LocTriggerData;
  	HeapTuple	trigtuple;
  	HeapTuple	newtuple;
  	TupleTableSlot *newSlot;
  	int			i;
  
  	trigtuple = GetTupleForTrigger(estate, epqstate, relinfo, tupleid,
  								   &newSlot);
  	if (trigtuple == NULL)
  		return false;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
  		TRIGGER_EVENT_ROW |
  		TRIGGER_EVENT_BEFORE;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_ROW,
  								  TRIGGER_TYPE_BEFORE,
  								  TRIGGER_TYPE_DELETE))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, trigtuple, NULL))
  			continue;
  
  		LocTriggerData.tg_trigtuple = trigtuple;
  		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  		if (newtuple == NULL)
  		{
  			result = false;		/* tell caller to suppress delete */
  			break;
  		}
  		if (newtuple != trigtuple)
  			heap_freetuple(newtuple);
  	}
  	heap_freetuple(trigtuple);
  
  	return result;
  }
  
  void
  ExecARDeleteTriggers(EState *estate, ResultRelInfo *relinfo,
  					 ItemPointer tupleid)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc && trigdesc->trig_delete_after_row)
  	{
  		HeapTuple	trigtuple = GetTupleForTrigger(estate, NULL, relinfo,
  												   tupleid, NULL);
  
  		AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_DELETE,
  							  true, trigtuple, NULL, NIL, NULL);
  		heap_freetuple(trigtuple);
  	}
  }
  
  bool
  ExecIRDeleteTriggers(EState *estate, ResultRelInfo *relinfo,
  					 HeapTuple trigtuple)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  	TriggerData LocTriggerData;
  	HeapTuple	rettuple;
  	int			i;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
  		TRIGGER_EVENT_ROW |
  		TRIGGER_EVENT_INSTEAD;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_ROW,
  								  TRIGGER_TYPE_INSTEAD,
  								  TRIGGER_TYPE_DELETE))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, trigtuple, NULL))
  			continue;
  
  		LocTriggerData.tg_trigtuple = trigtuple;
  		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_trigger = trigger;
  		rettuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  		if (rettuple == NULL)
  			return false;		/* Delete was suppressed */
  		if (rettuple != trigtuple)
  			heap_freetuple(rettuple);
  	}
  	return true;
  }
  
  void
  ExecBSUpdateTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc;
  	int			i;
  	TriggerData LocTriggerData;
  	Bitmapset  *modifiedCols;
  
  	trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc == NULL)
  		return;
  	if (!trigdesc->trig_update_before_statement)
  		return;
  
  	modifiedCols = GetModifiedColumns(relinfo, estate);
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
  		TRIGGER_EVENT_BEFORE;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_trigtuple = NULL;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  		HeapTuple	newtuple;
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_STATEMENT,
  								  TRIGGER_TYPE_BEFORE,
  								  TRIGGER_TYPE_UPDATE))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							modifiedCols, NULL, NULL))
  			continue;
  
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  
  		if (newtuple)
  			ereport(ERROR,
  					(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
  				  errmsg("BEFORE STATEMENT trigger cannot return a value")));
  	}
  }
  
  void
  ExecASUpdateTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc && trigdesc->trig_update_after_statement)
  		AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_UPDATE,
  							  false, NULL, NULL, NIL,
  							  GetModifiedColumns(relinfo, estate));
  }
  
  TupleTableSlot *
  ExecBRUpdateTriggers(EState *estate, EPQState *epqstate,
  					 ResultRelInfo *relinfo,
  					 ItemPointer tupleid, TupleTableSlot *slot)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  	HeapTuple	slottuple = ExecMaterializeSlot(slot);
  	HeapTuple	newtuple = slottuple;
  	TriggerData LocTriggerData;
  	HeapTuple	trigtuple;
  	HeapTuple	oldtuple;
  	TupleTableSlot *newSlot;
  	int			i;
  	Bitmapset  *modifiedCols;
  
  	/* get a copy of the on-disk tuple we are planning to update */
  	trigtuple = GetTupleForTrigger(estate, epqstate, relinfo, tupleid,
  								   &newSlot);
  	if (trigtuple == NULL)
  		return NULL;			/* cancel the update action */
  
  	/*
  	 * In READ COMMITTED isolation level it's possible that target tuple was
  	 * changed due to concurrent update.  In that case we have a raw subplan
  	 * output tuple in newSlot, and need to run it through the junk filter to
  	 * produce an insertable tuple.
  	 *
  	 * Caution: more than likely, the passed-in slot is the same as the
  	 * junkfilter's output slot, so we are clobbering the original value of
  	 * slottuple by doing the filtering.  This is OK since neither we nor our
  	 * caller have any more interest in the prior contents of that slot.
  	 */
  	if (newSlot != NULL)
  	{
  		slot = ExecFilterJunk(relinfo->ri_junkFilter, newSlot);
  		slottuple = ExecMaterializeSlot(slot);
  		newtuple = slottuple;
  	}
  
  	modifiedCols = GetModifiedColumns(relinfo, estate);
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
  		TRIGGER_EVENT_ROW |
  		TRIGGER_EVENT_BEFORE;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_ROW,
  								  TRIGGER_TYPE_BEFORE,
  								  TRIGGER_TYPE_UPDATE))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							modifiedCols, trigtuple, newtuple))
  			continue;
  
  		LocTriggerData.tg_trigtuple = trigtuple;
  		LocTriggerData.tg_newtuple = oldtuple = newtuple;
  		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  		if (oldtuple != newtuple && oldtuple != slottuple)
  			heap_freetuple(oldtuple);
  		if (newtuple == NULL)
  		{
  			heap_freetuple(trigtuple);
  			return NULL;		/* "do nothing" */
  		}
  	}
  	heap_freetuple(trigtuple);
  
  	if (newtuple != slottuple)
  	{
  		/*
  		 * Return the modified tuple using the es_trig_tuple_slot.  We assume
  		 * the tuple was allocated in per-tuple memory context, and therefore
  		 * will go away by itself. The tuple table slot should not try to
  		 * clear it.
  		 */
  		TupleTableSlot *newslot = estate->es_trig_tuple_slot;
  		TupleDesc	tupdesc = RelationGetDescr(relinfo->ri_RelationDesc);
  
  		if (newslot->tts_tupleDescriptor != tupdesc)
  			ExecSetSlotDescriptor(newslot, tupdesc);
  		ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
  		slot = newslot;
  	}
  	return slot;
  }
  
  void
  ExecARUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
  					 ItemPointer tupleid, HeapTuple newtuple,
  					 List *recheckIndexes)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc && trigdesc->trig_update_after_row)
  	{
  		HeapTuple	trigtuple = GetTupleForTrigger(estate, NULL, relinfo,
  												   tupleid, NULL);
  
  		AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_UPDATE,
  							  true, trigtuple, newtuple, recheckIndexes,
  							  GetModifiedColumns(relinfo, estate));
  		heap_freetuple(trigtuple);
  	}
  }
  
  TupleTableSlot *
  ExecIRUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
  					 HeapTuple trigtuple, TupleTableSlot *slot)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  	HeapTuple	slottuple = ExecMaterializeSlot(slot);
  	HeapTuple	newtuple = slottuple;
  	TriggerData LocTriggerData;
  	HeapTuple	oldtuple;
  	int			i;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
  		TRIGGER_EVENT_ROW |
  		TRIGGER_EVENT_INSTEAD;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_ROW,
  								  TRIGGER_TYPE_INSTEAD,
  								  TRIGGER_TYPE_UPDATE))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, trigtuple, newtuple))
  			continue;
  
  		LocTriggerData.tg_trigtuple = trigtuple;
  		LocTriggerData.tg_newtuple = oldtuple = newtuple;
  		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  		if (oldtuple != newtuple && oldtuple != slottuple)
  			heap_freetuple(oldtuple);
  		if (newtuple == NULL)
  			return NULL;		/* "do nothing" */
  	}
  
  	if (newtuple != slottuple)
  	{
  		/*
  		 * Return the modified tuple using the es_trig_tuple_slot.  We assume
  		 * the tuple was allocated in per-tuple memory context, and therefore
  		 * will go away by itself. The tuple table slot should not try to
  		 * clear it.
  		 */
  		TupleTableSlot *newslot = estate->es_trig_tuple_slot;
  		TupleDesc	tupdesc = RelationGetDescr(relinfo->ri_RelationDesc);
  
  		if (newslot->tts_tupleDescriptor != tupdesc)
  			ExecSetSlotDescriptor(newslot, tupdesc);
  		ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
  		slot = newslot;
  	}
  	return slot;
  }
  
  void
  ExecBSTruncateTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc;
  	int			i;
  	TriggerData LocTriggerData;
  
  	trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc == NULL)
  		return;
  	if (!trigdesc->trig_truncate_before_statement)
  		return;
  
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event = TRIGGER_EVENT_TRUNCATE |
  		TRIGGER_EVENT_BEFORE;
  	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  	LocTriggerData.tg_trigtuple = NULL;
  	LocTriggerData.tg_newtuple = NULL;
  	LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  		HeapTuple	newtuple;
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  TRIGGER_TYPE_STATEMENT,
  								  TRIGGER_TYPE_BEFORE,
  								  TRIGGER_TYPE_TRUNCATE))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
  							NULL, NULL, NULL))
  			continue;
  
  		LocTriggerData.tg_trigger = trigger;
  		newtuple = ExecCallTriggerFunc(&LocTriggerData,
  									   i,
  									   relinfo->ri_TrigFunctions,
  									   relinfo->ri_TrigInstrument,
  									   GetPerTupleMemoryContext(estate));
  
  		if (newtuple)
  			ereport(ERROR,
  					(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
  				  errmsg("BEFORE STATEMENT trigger cannot return a value")));
  	}
  }
  
  void
  ExecASTruncateTriggers(EState *estate, ResultRelInfo *relinfo)
  {
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  
  	if (trigdesc && trigdesc->trig_truncate_after_statement)
  		AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_TRUNCATE,
  							  false, NULL, NULL, NIL, NULL);
  }
  
  
  static HeapTuple
  GetTupleForTrigger(EState *estate,
  				   EPQState *epqstate,
  				   ResultRelInfo *relinfo,
  				   ItemPointer tid,
  				   TupleTableSlot **newSlot)
  {
  	Relation	relation = relinfo->ri_RelationDesc;
  	HeapTupleData tuple;
  	HeapTuple	result;
  	Buffer		buffer;
  
  	if (newSlot != NULL)
  	{
  		HTSU_Result test;
  		ItemPointerData update_ctid;
  		TransactionId update_xmax;
  
  		*newSlot = NULL;
  
  		/* caller must pass an epqstate if EvalPlanQual is possible */
  		Assert(epqstate != NULL);
  
  		/*
  		 * lock tuple for update
  		 */
  ltrmark:;
  		tuple.t_self = *tid;
  		test = heap_lock_tuple(relation, &tuple, &buffer,
  							   &update_ctid, &update_xmax,
  							   estate->es_output_cid,
  							   LockTupleExclusive, false);
  		switch (test)
  		{
  			case HeapTupleSelfUpdated:
  				/* treat it as deleted; do not process */
  				ReleaseBuffer(buffer);
  				return NULL;
  
  			case HeapTupleMayBeUpdated:
  				break;
  
  			case HeapTupleUpdated:
  				ReleaseBuffer(buffer);
  				if (IsolationUsesXactSnapshot())
  					ereport(ERROR,
  							(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
  							 errmsg("could not serialize access due to concurrent update")));
  				if (!ItemPointerEquals(&update_ctid, &tuple.t_self))
  				{
  					/* it was updated, so look at the updated version */
  					TupleTableSlot *epqslot;
  
  					epqslot = EvalPlanQual(estate,
  										   epqstate,
  										   relation,
  										   relinfo->ri_RangeTableIndex,
  										   &update_ctid,
  										   update_xmax);
  					if (!TupIsNull(epqslot))
  					{
  						*tid = update_ctid;
  						*newSlot = epqslot;
  
  						/*
  						 * EvalPlanQual already locked the tuple, but we
  						 * re-call heap_lock_tuple anyway as an easy way of
  						 * re-fetching the correct tuple.  Speed is hardly a
  						 * criterion in this path anyhow.
  						 */
  						goto ltrmark;
  					}
  				}
  
  				/*
  				 * if tuple was deleted or PlanQual failed for updated tuple -
  				 * we must not process this tuple!
  				 */
  				return NULL;
  
  			default:
  				ReleaseBuffer(buffer);
  				elog(ERROR, "unrecognized heap_lock_tuple status: %u", test);
  				return NULL;	/* keep compiler quiet */
  		}
  	}
  	else
  	{
  		Page		page;
  		ItemId		lp;
  
  		buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
  
  		/*
  		 * Although we already know this tuple is valid, we must lock the
  		 * buffer to ensure that no one has a buffer cleanup lock; otherwise
  		 * they might move the tuple while we try to copy it.  But we can
  		 * release the lock before actually doing the heap_copytuple call,
  		 * since holding pin is sufficient to prevent anyone from getting a
  		 * cleanup lock they don't already hold.
  		 */
  		LockBuffer(buffer, BUFFER_LOCK_SHARE);
  
  		page = BufferGetPage(buffer);
  		lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid));
  
  		Assert(ItemIdIsNormal(lp));
  
  		tuple.t_data = (HeapTupleHeader) PageGetItem(page, lp);
  		tuple.t_len = ItemIdGetLength(lp);
  		tuple.t_self = *tid;
  		tuple.t_tableOid = RelationGetRelid(relation);
  
  		LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
  	}
  
  	result = heap_copytuple(&tuple);
  	ReleaseBuffer(buffer);
  
  	return result;
  }
  
  /*
   * Is trigger enabled to fire?
   */
  static bool
  TriggerEnabled(EState *estate, ResultRelInfo *relinfo,
  			   Trigger *trigger, TriggerEvent event,
  			   Bitmapset *modifiedCols,
  			   HeapTuple oldtup, HeapTuple newtup)
  {
  	/* Check replication-role-dependent enable state */
  	if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
  	{
  		if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
  			trigger->tgenabled == TRIGGER_DISABLED)
  			return false;
  	}
  	else	/* ORIGIN or LOCAL role */
  	{
  		if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
  			trigger->tgenabled == TRIGGER_DISABLED)
  			return false;
  	}
  
  	/*
  	 * Check for column-specific trigger (only possible for UPDATE, and in
  	 * fact we *must* ignore tgattr for other event types)
  	 */
  	if (trigger->tgnattr > 0 && TRIGGER_FIRED_BY_UPDATE(event))
  	{
  		int			i;
  		bool		modified;
  
  		modified = false;
  		for (i = 0; i < trigger->tgnattr; i++)
  		{
  			if (bms_is_member(trigger->tgattr[i] - FirstLowInvalidHeapAttributeNumber,
  							  modifiedCols))
  			{
  				modified = true;
  				break;
  			}
  		}
  		if (!modified)
  			return false;
  	}
  
  	/* Check for WHEN clause */
  	if (trigger->tgqual)
  	{
  		TupleDesc	tupdesc = RelationGetDescr(relinfo->ri_RelationDesc);
  		List	  **predicate;
  		ExprContext *econtext;
  		TupleTableSlot *oldslot = NULL;
  		TupleTableSlot *newslot = NULL;
  		MemoryContext oldContext;
  		int			i;
  
  		Assert(estate != NULL);
  
  		/*
  		 * trigger is an element of relinfo->ri_TrigDesc->triggers[]; find the
  		 * matching element of relinfo->ri_TrigWhenExprs[]
  		 */
  		i = trigger - relinfo->ri_TrigDesc->triggers;
  		predicate = &relinfo->ri_TrigWhenExprs[i];
  
  		/*
  		 * If first time through for this WHEN expression, build expression
  		 * nodetrees for it.  Keep them in the per-query memory context so
  		 * they'll survive throughout the query.
  		 */
  		if (*predicate == NIL)
  		{
  			Node	   *tgqual;
  
  			oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
  			tgqual = stringToNode(trigger->tgqual);
  			/* Change references to OLD and NEW to INNER_VAR and OUTER_VAR */
  			ChangeVarNodes(tgqual, PRS2_OLD_VARNO, INNER_VAR, 0);
  			ChangeVarNodes(tgqual, PRS2_NEW_VARNO, OUTER_VAR, 0);
  			/* ExecQual wants implicit-AND form */
  			tgqual = (Node *) make_ands_implicit((Expr *) tgqual);
  			*predicate = (List *) ExecPrepareExpr((Expr *) tgqual, estate);
  			MemoryContextSwitchTo(oldContext);
  		}
  
  		/*
  		 * We will use the EState's per-tuple context for evaluating WHEN
  		 * expressions (creating it if it's not already there).
  		 */
  		econtext = GetPerTupleExprContext(estate);
  
  		/*
  		 * Put OLD and NEW tuples into tupleslots for expression evaluation.
  		 * These slots can be shared across the whole estate, but be careful
  		 * that they have the current resultrel's tupdesc.
  		 */
  		if (HeapTupleIsValid(oldtup))
  		{
  			if (estate->es_trig_oldtup_slot == NULL)
  			{
  				oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
  				estate->es_trig_oldtup_slot = ExecInitExtraTupleSlot(estate);
  				MemoryContextSwitchTo(oldContext);
  			}
  			oldslot = estate->es_trig_oldtup_slot;
  			if (oldslot->tts_tupleDescriptor != tupdesc)
  				ExecSetSlotDescriptor(oldslot, tupdesc);
  			ExecStoreTuple(oldtup, oldslot, InvalidBuffer, false);
  		}
  		if (HeapTupleIsValid(newtup))
  		{
  			if (estate->es_trig_newtup_slot == NULL)
  			{
  				oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
  				estate->es_trig_newtup_slot = ExecInitExtraTupleSlot(estate);
  				MemoryContextSwitchTo(oldContext);
  			}
  			newslot = estate->es_trig_newtup_slot;
  			if (newslot->tts_tupleDescriptor != tupdesc)
  				ExecSetSlotDescriptor(newslot, tupdesc);
  			ExecStoreTuple(newtup, newslot, InvalidBuffer, false);
  		}
  
  		/*
  		 * Finally evaluate the expression, making the old and/or new tuples
  		 * available as INNER_VAR/OUTER_VAR respectively.
  		 */
  		econtext->ecxt_innertuple = oldslot;
  		econtext->ecxt_outertuple = newslot;
  		if (!ExecQual(*predicate, econtext, false))
  			return false;
  	}
  
  	return true;
  }
  
  
  /* ----------
   * After-trigger stuff
   *
   * The AfterTriggersData struct holds data about pending AFTER trigger events
   * during the current transaction tree.  (BEFORE triggers are fired
   * immediately so we don't need any persistent state about them.)  The struct
   * and most of its subsidiary data are kept in TopTransactionContext; however
   * the individual event records are kept in a separate sub-context.  This is
   * done mainly so that it's easy to tell from a memory context dump how much
   * space is being eaten by trigger events.
   *
   * Because the list of pending events can grow large, we go to some
   * considerable effort to minimize per-event memory consumption.  The event
   * records are grouped into chunks and common data for similar events in the
   * same chunk is only stored once.
   *
   * XXX We need to be able to save the per-event data in a file if it grows too
   * large.
   * ----------
   */
  
  /* Per-trigger SET CONSTRAINT status */
  typedef struct SetConstraintTriggerData
  {
  	Oid			sct_tgoid;
  	bool		sct_tgisdeferred;
  } SetConstraintTriggerData;
  
  typedef struct SetConstraintTriggerData *SetConstraintTrigger;
  
  /*
   * SET CONSTRAINT intra-transaction status.
   *
   * We make this a single palloc'd object so it can be copied and freed easily.
   *
   * all_isset and all_isdeferred are used to keep track
   * of SET CONSTRAINTS ALL {DEFERRED, IMMEDIATE}.
   *
   * trigstates[] stores per-trigger tgisdeferred settings.
   */
  typedef struct SetConstraintStateData
  {
  	bool		all_isset;
  	bool		all_isdeferred;
  	int			numstates;		/* number of trigstates[] entries in use */
  	int			numalloc;		/* allocated size of trigstates[] */
  	SetConstraintTriggerData trigstates[1];		/* VARIABLE LENGTH ARRAY */
  } SetConstraintStateData;
  
  typedef SetConstraintStateData *SetConstraintState;
  
  
  /*
   * Per-trigger-event data
   *
   * The actual per-event data, AfterTriggerEventData, includes DONE/IN_PROGRESS
   * status bits and one or two tuple CTIDs.  Each event record also has an
   * associated AfterTriggerSharedData that is shared across all instances
   * of similar events within a "chunk".
   *
   * We arrange not to waste storage on ate_ctid2 for non-update events.
   * We could go further and not store either ctid for statement-level triggers,
   * but that seems unlikely to be worth the trouble.
   *
   * Note: ats_firing_id is initially zero and is set to something else when
   * AFTER_TRIGGER_IN_PROGRESS is set.  It indicates which trigger firing
   * cycle the trigger will be fired in (or was fired in, if DONE is set).
   * Although this is mutable state, we can keep it in AfterTriggerSharedData
   * because all instances of the same type of event in a given event list will
   * be fired at the same time, if they were queued between the same firing
   * cycles.  So we need only ensure that ats_firing_id is zero when attaching
   * a new event to an existing AfterTriggerSharedData record.
   */
  typedef uint32 TriggerFlags;
  
  #define AFTER_TRIGGER_OFFSET			0x0FFFFFFF		/* must be low-order
  														 * bits */
  #define AFTER_TRIGGER_2CTIDS			0x10000000
  #define AFTER_TRIGGER_DONE				0x20000000
  #define AFTER_TRIGGER_IN_PROGRESS		0x40000000
  
  typedef struct AfterTriggerSharedData *AfterTriggerShared;
  
  typedef struct AfterTriggerSharedData
  {
  	TriggerEvent ats_event;		/* event type indicator, see trigger.h */
  	Oid			ats_tgoid;		/* the trigger's ID */
  	Oid			ats_relid;		/* the relation it's on */
  	CommandId	ats_firing_id;	/* ID for firing cycle */
  } AfterTriggerSharedData;
  
  typedef struct AfterTriggerEventData *AfterTriggerEvent;
  
  typedef struct AfterTriggerEventData
  {
  	TriggerFlags ate_flags;		/* status bits and offset to shared data */
  	ItemPointerData ate_ctid1;	/* inserted, deleted, or old updated tuple */
  	ItemPointerData ate_ctid2;	/* new updated tuple */
  } AfterTriggerEventData;
  
  /* This struct must exactly match the one above except for not having ctid2 */
  typedef struct AfterTriggerEventDataOneCtid
  {
  	TriggerFlags ate_flags;		/* status bits and offset to shared data */
  	ItemPointerData ate_ctid1;	/* inserted, deleted, or old updated tuple */
  }	AfterTriggerEventDataOneCtid;
  
  #define SizeofTriggerEvent(evt) \
  	(((evt)->ate_flags & AFTER_TRIGGER_2CTIDS) ? \
  	 sizeof(AfterTriggerEventData) : sizeof(AfterTriggerEventDataOneCtid))
  
  #define GetTriggerSharedData(evt) \
  	((AfterTriggerShared) ((char *) (evt) + ((evt)->ate_flags & AFTER_TRIGGER_OFFSET)))
  
  /*
   * To avoid palloc overhead, we keep trigger events in arrays in successively-
   * larger chunks (a slightly more sophisticated version of an expansible
   * array).  The space between CHUNK_DATA_START and freeptr is occupied by
   * AfterTriggerEventData records; the space between endfree and endptr is
   * occupied by AfterTriggerSharedData records.
   */
  typedef struct AfterTriggerEventChunk
  {
  	struct AfterTriggerEventChunk *next;		/* list link */
  	char	   *freeptr;		/* start of free space in chunk */
  	char	   *endfree;		/* end of free space in chunk */
  	char	   *endptr;			/* end of chunk */
  	/* event data follows here */
  } AfterTriggerEventChunk;
  
  #define CHUNK_DATA_START(cptr) ((char *) (cptr) + MAXALIGN(sizeof(AfterTriggerEventChunk)))
  
  /* A list of events */
  typedef struct AfterTriggerEventList
  {
  	AfterTriggerEventChunk *head;
  	AfterTriggerEventChunk *tail;
  	char	   *tailfree;		/* freeptr of tail chunk */
  } AfterTriggerEventList;
  
  /* Macros to help in iterating over a list of events */
  #define for_each_chunk(cptr, evtlist) \
  	for (cptr = (evtlist).head; cptr != NULL; cptr = cptr->next)
  #define for_each_event(eptr, cptr) \
  	for (eptr = (AfterTriggerEvent) CHUNK_DATA_START(cptr); \
  		 (char *) eptr < (cptr)->freeptr; \
  		 eptr = (AfterTriggerEvent) (((char *) eptr) + SizeofTriggerEvent(eptr)))
  /* Use this if no special per-chunk processing is needed */
  #define for_each_event_chunk(eptr, cptr, evtlist) \
  	for_each_chunk(cptr, evtlist) for_each_event(eptr, cptr)
  
  
  /*
   * All per-transaction data for the AFTER TRIGGERS module.
   *
   * AfterTriggersData has the following fields:
   *
   * firing_counter is incremented for each call of afterTriggerInvokeEvents.
   * We mark firable events with the current firing cycle's ID so that we can
   * tell which ones to work on.  This ensures sane behavior if a trigger
   * function chooses to do SET CONSTRAINTS: the inner SET CONSTRAINTS will
   * only fire those events that weren't already scheduled for firing.
   *
   * state keeps track of the transaction-local effects of SET CONSTRAINTS.
   * This is saved and restored across failed subtransactions.
   *
   * events is the current list of deferred events.  This is global across
   * all subtransactions of the current transaction.  In a subtransaction
   * abort, we know that the events added by the subtransaction are at the
   * end of the list, so it is relatively easy to discard them.  The event
   * list chunks themselves are stored in event_cxt.
   *
   * query_depth is the current depth of nested AfterTriggerBeginQuery calls
   * (-1 when the stack is empty).
   *
   * query_stack[query_depth] is a list of AFTER trigger events queued by the
   * current query (and the query_stack entries below it are lists of trigger
   * events queued by calling queries).  None of these are valid until the
   * matching AfterTriggerEndQuery call occurs.  At that point we fire
   * immediate-mode triggers, and append any deferred events to the main events
   * list.
   *
   * maxquerydepth is just the allocated length of query_stack.
   *
   * state_stack is a stack of pointers to saved copies of the SET CONSTRAINTS
   * state data; each subtransaction level that modifies that state first
   * saves a copy, which we use to restore the state if we abort.
   *
   * events_stack is a stack of copies of the events head/tail pointers,
   * which we use to restore those values during subtransaction abort.
   *
   * depth_stack is a stack of copies of subtransaction-start-time query_depth,
   * which we similarly use to clean up at subtransaction abort.
   *
   * firing_stack is a stack of copies of subtransaction-start-time
   * firing_counter.  We use this to recognize which deferred triggers were
   * fired (or marked for firing) within an aborted subtransaction.
   *
   * We use GetCurrentTransactionNestLevel() to determine the correct array
   * index in these stacks.  maxtransdepth is the number of allocated entries in
   * each stack.  (By not keeping our own stack pointer, we can avoid trouble
   * in cases where errors during subxact abort cause multiple invocations
   * of AfterTriggerEndSubXact() at the same nesting depth.)
   */
  typedef struct AfterTriggersData
  {
  	CommandId	firing_counter; /* next firing ID to assign */
  	SetConstraintState state;	/* the active S C state */
  	AfterTriggerEventList events;		/* deferred-event list */
  	int			query_depth;	/* current query list index */
  	AfterTriggerEventList *query_stack; /* events pending from each query */
  	int			maxquerydepth;	/* allocated len of above array */
  	MemoryContext event_cxt;	/* memory context for events, if any */
  
  	/* these fields are just for resetting at subtrans abort: */
  
  	SetConstraintState *state_stack;	/* stacked S C states */
  	AfterTriggerEventList *events_stack;		/* stacked list pointers */
  	int		   *depth_stack;	/* stacked query_depths */
  	CommandId  *firing_stack;	/* stacked firing_counters */
  	int			maxtransdepth;	/* allocated len of above arrays */
  } AfterTriggersData;
  
  typedef AfterTriggersData *AfterTriggers;
  
  static AfterTriggers afterTriggers;
  
  
  static void AfterTriggerExecute(AfterTriggerEvent event,
  					Relation rel, TriggerDesc *trigdesc,
  					FmgrInfo *finfo,
  					Instrumentation *instr,
  					MemoryContext per_tuple_context);
  static SetConstraintState SetConstraintStateCreate(int numalloc);
  static SetConstraintState SetConstraintStateCopy(SetConstraintState state);
  static SetConstraintState SetConstraintStateAddItem(SetConstraintState state,
  						  Oid tgoid, bool tgisdeferred);
  
  
  /* ----------
   * afterTriggerCheckState()
   *
   *	Returns true if the trigger event is actually in state DEFERRED.
   * ----------
   */
  static bool
  afterTriggerCheckState(AfterTriggerShared evtshared)
  {
  	Oid			tgoid = evtshared->ats_tgoid;
  	SetConstraintState state = afterTriggers->state;
  	int			i;
  
  	/*
  	 * For not-deferrable triggers (i.e. normal AFTER ROW triggers and
  	 * constraints declared NOT DEFERRABLE), the state is always false.
  	 */
  	if ((evtshared->ats_event & AFTER_TRIGGER_DEFERRABLE) == 0)
  		return false;
  
  	/*
  	 * Check if SET CONSTRAINTS has been executed for this specific trigger.
  	 */
  	for (i = 0; i < state->numstates; i++)
  	{
  		if (state->trigstates[i].sct_tgoid == tgoid)
  			return state->trigstates[i].sct_tgisdeferred;
  	}
  
  	/*
  	 * Check if SET CONSTRAINTS ALL has been executed; if so use that.
  	 */
  	if (state->all_isset)
  		return state->all_isdeferred;
  
  	/*
  	 * Otherwise return the default state for the trigger.
  	 */
  	return ((evtshared->ats_event & AFTER_TRIGGER_INITDEFERRED) != 0);
  }
  
  
  /* ----------
   * afterTriggerAddEvent()
   *
   *	Add a new trigger event to the specified queue.
   *	The passed-in event data is copied.
   * ----------
   */
  static void
  afterTriggerAddEvent(AfterTriggerEventList *events,
  					 AfterTriggerEvent event, AfterTriggerShared evtshared)
  {
  	Size		eventsize = SizeofTriggerEvent(event);
  	Size		needed = eventsize + sizeof(AfterTriggerSharedData);
  	AfterTriggerEventChunk *chunk;
  	AfterTriggerShared newshared;
  	AfterTriggerEvent newevent;
  
  	/*
  	 * If empty list or not enough room in the tail chunk, make a new chunk.
  	 * We assume here that a new shared record will always be needed.
  	 */
  	chunk = events->tail;
  	if (chunk == NULL ||
  		chunk->endfree - chunk->freeptr < needed)
  	{
  		Size		chunksize;
  
  		/* Create event context if we didn't already */
  		if (afterTriggers->event_cxt == NULL)
  			afterTriggers->event_cxt =
  				AllocSetContextCreate(TopTransactionContext,
  									  "AfterTriggerEvents",
  									  ALLOCSET_DEFAULT_MINSIZE,
  									  ALLOCSET_DEFAULT_INITSIZE,
  									  ALLOCSET_DEFAULT_MAXSIZE);
  
  		/*
  		 * Chunk size starts at 1KB and is allowed to increase up to 1MB.
  		 * These numbers are fairly arbitrary, though there is a hard limit at
  		 * AFTER_TRIGGER_OFFSET; else we couldn't link event records to their
  		 * shared records using the available space in ate_flags.  Another
  		 * constraint is that if the chunk size gets too huge, the search loop
  		 * below would get slow given a (not too common) usage pattern with
  		 * many distinct event types in a chunk.  Therefore, we double the
  		 * preceding chunk size only if there weren't too many shared records
  		 * in the preceding chunk; otherwise we halve it.  This gives us some
  		 * ability to adapt to the actual usage pattern of the current query
  		 * while still having large chunk sizes in typical usage.  All chunk
  		 * sizes used should be MAXALIGN multiples, to ensure that the shared
  		 * records will be aligned safely.
  		 */
  #define MIN_CHUNK_SIZE 1024
  #define MAX_CHUNK_SIZE (1024*1024)
  
  #if MAX_CHUNK_SIZE > (AFTER_TRIGGER_OFFSET+1)
  #error MAX_CHUNK_SIZE must not exceed AFTER_TRIGGER_OFFSET
  #endif
  
  		if (chunk == NULL)
  			chunksize = MIN_CHUNK_SIZE;
  		else
  		{
  			/* preceding chunk size... */
  			chunksize = chunk->endptr - (char *) chunk;
  			/* check number of shared records in preceding chunk */
  			if ((chunk->endptr - chunk->endfree) <=
  				(100 * sizeof(AfterTriggerSharedData)))
  				chunksize *= 2; /* okay, double it */
  			else
  				chunksize /= 2; /* too many shared records */
  			chunksize = Min(chunksize, MAX_CHUNK_SIZE);
  		}
  		chunk = MemoryContextAlloc(afterTriggers->event_cxt, chunksize);
  		chunk->next = NULL;
  		chunk->freeptr = CHUNK_DATA_START(chunk);
  		chunk->endptr = chunk->endfree = (char *) chunk + chunksize;
  		Assert(chunk->endfree - chunk->freeptr >= needed);
  
  		if (events->head == NULL)
  			events->head = chunk;
  		else
  			events->tail->next = chunk;
  		events->tail = chunk;
  		/* events->tailfree is now out of sync, but we'll fix it below */
  	}
  
  	/*
  	 * Try to locate a matching shared-data record already in the chunk. If
  	 * none, make a new one.
  	 */
  	for (newshared = ((AfterTriggerShared) chunk->endptr) - 1;
  		 (char *) newshared >= chunk->endfree;
  		 newshared--)
  	{
  		if (newshared->ats_tgoid == evtshared->ats_tgoid &&
  			newshared->ats_relid == evtshared->ats_relid &&
  			newshared->ats_event == evtshared->ats_event &&
  			newshared->ats_firing_id == 0)
  			break;
  	}
  	if ((char *) newshared < chunk->endfree)
  	{
  		*newshared = *evtshared;
  		newshared->ats_firing_id = 0;	/* just to be sure */
  		chunk->endfree = (char *) newshared;
  	}
  
  	/* Insert the data */
  	newevent = (AfterTriggerEvent) chunk->freeptr;
  	memcpy(newevent, event, eventsize);
  	/* ... and link the new event to its shared record */
  	newevent->ate_flags &= ~AFTER_TRIGGER_OFFSET;
  	newevent->ate_flags |= (char *) newshared - (char *) newevent;
  
  	chunk->freeptr += eventsize;
  	events->tailfree = chunk->freeptr;
  }
  
  /* ----------
   * afterTriggerFreeEventList()
   *
   *	Free all the event storage in the given list.
   * ----------
   */
  static void
  afterTriggerFreeEventList(AfterTriggerEventList *events)
  {
  	AfterTriggerEventChunk *chunk;
  
  	while ((chunk = events->head) != NULL)
  	{
  		events->head = chunk->next;
  		pfree(chunk);
  	}
  	events->tail = NULL;
  	events->tailfree = NULL;
  }
  
  /* ----------
   * afterTriggerRestoreEventList()
   *
   *	Restore an event list to its prior length, removing all the events
   *	added since it had the value old_events.
   * ----------
   */
  static void
  afterTriggerRestoreEventList(AfterTriggerEventList *events,
  							 const AfterTriggerEventList *old_events)
  {
  	AfterTriggerEventChunk *chunk;
  	AfterTriggerEventChunk *next_chunk;
  
  	if (old_events->tail == NULL)
  	{
  		/* restoring to a completely empty state, so free everything */
  		afterTriggerFreeEventList(events);
  	}
  	else
  	{
  		*events = *old_events;
  		/* free any chunks after the last one we want to keep */
  		for (chunk = events->tail->next; chunk != NULL; chunk = next_chunk)
  		{
  			next_chunk = chunk->next;
  			pfree(chunk);
  		}
  		/* and clean up the tail chunk to be the right length */
  		events->tail->next = NULL;
  		events->tail->freeptr = events->tailfree;
  
  		/*
  		 * We don't make any effort to remove now-unused shared data records.
  		 * They might still be useful, anyway.
  		 */
  	}
  }
  
  /* ----------
   * afterTriggerDeleteHeadEventChunk()
   *
   *	Remove the first chunk of events from the given event list.
   * ----------
   */
  static void
  afterTriggerDeleteHeadEventChunk(AfterTriggerEventList *events)
  {
  	AfterTriggerEventChunk *target = events->head;
  
  	Assert(target && target->next);
  
  	events->head = target->next;
  	pfree(target);
  }
  
  
  /* ----------
   * AfterTriggerExecute()
   *
   *	Fetch the required tuples back from the heap and fire one
   *	single trigger function.
   *
   *	Frequently, this will be fired many times in a row for triggers of
   *	a single relation.  Therefore, we cache the open relation and provide
   *	fmgr lookup cache space at the caller level.  (For triggers fired at
   *	the end of a query, we can even piggyback on the executor's state.)
   *
   *	event: event currently being fired.
   *	rel: open relation for event.
   *	trigdesc: working copy of rel's trigger info.
   *	finfo: array of fmgr lookup cache entries (one per trigger in trigdesc).
   *	instr: array of EXPLAIN ANALYZE instrumentation nodes (one per trigger),
   *		or NULL if no instrumentation is wanted.
   *	per_tuple_context: memory context to call trigger function in.
   * ----------
   */
  static void
  AfterTriggerExecute(AfterTriggerEvent event,
  					Relation rel, TriggerDesc *trigdesc,
  					FmgrInfo *finfo, Instrumentation *instr,
  					MemoryContext per_tuple_context)
  {
  	AfterTriggerShared evtshared = GetTriggerSharedData(event);
  	Oid			tgoid = evtshared->ats_tgoid;
  	TriggerData LocTriggerData;
  	HeapTupleData tuple1;
  	HeapTupleData tuple2;
  	HeapTuple	rettuple;
  	Buffer		buffer1 = InvalidBuffer;
  	Buffer		buffer2 = InvalidBuffer;
  	int			tgindx;
  
  	/*
  	 * Locate trigger in trigdesc.
  	 */
  	LocTriggerData.tg_trigger = NULL;
  	for (tgindx = 0; tgindx < trigdesc->numtriggers; tgindx++)
  	{
  		if (trigdesc->triggers[tgindx].tgoid == tgoid)
  		{
  			LocTriggerData.tg_trigger = &(trigdesc->triggers[tgindx]);
  			break;
  		}
  	}
  	if (LocTriggerData.tg_trigger == NULL)
  		elog(ERROR, "could not find trigger %u", tgoid);
  
  	/*
  	 * If doing EXPLAIN ANALYZE, start charging time to this trigger. We want
  	 * to include time spent re-fetching tuples in the trigger cost.
  	 */
  	if (instr)
  		InstrStartNode(instr + tgindx);
  
  	/*
  	 * Fetch the required tuple(s).
  	 */
  	if (ItemPointerIsValid(&(event->ate_ctid1)))
  	{
  		ItemPointerCopy(&(event->ate_ctid1), &(tuple1.t_self));
  		if (!heap_fetch(rel, SnapshotAny, &tuple1, &buffer1, false, NULL))
  			elog(ERROR, "failed to fetch tuple1 for AFTER trigger");
  		LocTriggerData.tg_trigtuple = &tuple1;
  		LocTriggerData.tg_trigtuplebuf = buffer1;
  	}
  	else
  	{
  		LocTriggerData.tg_trigtuple = NULL;
  		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
  	}
  
  	/* don't touch ctid2 if not there */
  	if ((event->ate_flags & AFTER_TRIGGER_2CTIDS) &&
  		ItemPointerIsValid(&(event->ate_ctid2)))
  	{
  		ItemPointerCopy(&(event->ate_ctid2), &(tuple2.t_self));
  		if (!heap_fetch(rel, SnapshotAny, &tuple2, &buffer2, false, NULL))
  			elog(ERROR, "failed to fetch tuple2 for AFTER trigger");
  		LocTriggerData.tg_newtuple = &tuple2;
  		LocTriggerData.tg_newtuplebuf = buffer2;
  	}
  	else
  	{
  		LocTriggerData.tg_newtuple = NULL;
  		LocTriggerData.tg_newtuplebuf = InvalidBuffer;
  	}
  
  	/*
  	 * Setup the remaining trigger information
  	 */
  	LocTriggerData.type = T_TriggerData;
  	LocTriggerData.tg_event =
  		evtshared->ats_event & (TRIGGER_EVENT_OPMASK | TRIGGER_EVENT_ROW);
  	LocTriggerData.tg_relation = rel;
  
  	MemoryContextReset(per_tuple_context);
  
  	/*
  	 * Call the trigger and throw away any possibly returned updated tuple.
  	 * (Don't let ExecCallTriggerFunc measure EXPLAIN time.)
  	 */
  	rettuple = ExecCallTriggerFunc(&LocTriggerData,
  								   tgindx,
  								   finfo,
  								   NULL,
  								   per_tuple_context);
  	if (rettuple != NULL && rettuple != &tuple1 && rettuple != &tuple2)
  		heap_freetuple(rettuple);
  
  	/*
  	 * Release buffers
  	 */
  	if (buffer1 != InvalidBuffer)
  		ReleaseBuffer(buffer1);
  	if (buffer2 != InvalidBuffer)
  		ReleaseBuffer(buffer2);
  
  	/*
  	 * If doing EXPLAIN ANALYZE, stop charging time to this trigger, and count
  	 * one "tuple returned" (really the number of firings).
  	 */
  	if (instr)
  		InstrStopNode(instr + tgindx, 1);
  }
  
  
  /*
   * afterTriggerMarkEvents()
   *
   *	Scan the given event list for not yet invoked events.  Mark the ones
   *	that can be invoked now with the current firing ID.
   *
   *	If move_list isn't NULL, events that are not to be invoked now are
   *	transferred to move_list.
   *
   *	When immediate_only is TRUE, do not invoke currently-deferred triggers.
   *	(This will be FALSE only at main transaction exit.)
   *
   *	Returns TRUE if any invokable events were found.
   */
  static bool
  afterTriggerMarkEvents(AfterTriggerEventList *events,
  					   AfterTriggerEventList *move_list,
  					   bool immediate_only)
  {
  	bool		found = false;
  	AfterTriggerEvent event;
  	AfterTriggerEventChunk *chunk;
  
  	for_each_event_chunk(event, chunk, *events)
  	{
  		AfterTriggerShared evtshared = GetTriggerSharedData(event);
  		bool		defer_it = false;
  
  		if (!(event->ate_flags &
  			  (AFTER_TRIGGER_DONE | AFTER_TRIGGER_IN_PROGRESS)))
  		{
  			/*
  			 * This trigger hasn't been called or scheduled yet. Check if we
  			 * should call it now.
  			 */
  			if (immediate_only && afterTriggerCheckState(evtshared))
  			{
  				defer_it = true;
  			}
  			else
  			{
  				/*
  				 * Mark it as to be fired in this firing cycle.
  				 */
  				evtshared->ats_firing_id = afterTriggers->firing_counter;
  				event->ate_flags |= AFTER_TRIGGER_IN_PROGRESS;
  				found = true;
  			}
  		}
  
  		/*
  		 * If it's deferred, move it to move_list, if requested.
  		 */
  		if (defer_it && move_list != NULL)
  		{
  			/* add it to move_list */
  			afterTriggerAddEvent(move_list, event, evtshared);
  			/* mark original copy "done" so we don't do it again */
  			event->ate_flags |= AFTER_TRIGGER_DONE;
  		}
  	}
  
  	return found;
  }
  
  /*
   * afterTriggerInvokeEvents()
   *
   *	Scan the given event list for events that are marked as to be fired
   *	in the current firing cycle, and fire them.
   *
   *	If estate isn't NULL, we use its result relation info to avoid repeated
   *	openings and closing of trigger target relations.  If it is NULL, we
   *	make one locally to cache the info in case there are multiple trigger
   *	events per rel.
   *
   *	When delete_ok is TRUE, it's safe to delete fully-processed events.
   *	(We are not very tense about that: we simply reset a chunk to be empty
   *	if all its events got fired.  The objective here is just to avoid useless
   *	rescanning of events when a trigger queues new events during transaction
   *	end, so it's not necessary to worry much about the case where only
   *	some events are fired.)
   *
   *	Returns TRUE if no unfired events remain in the list (this allows us
   *	to avoid repeating afterTriggerMarkEvents).
   */
  static bool
  afterTriggerInvokeEvents(AfterTriggerEventList *events,
  						 CommandId firing_id,
  						 EState *estate,
  						 bool delete_ok)
  {
  	bool		all_fired = true;
  	AfterTriggerEventChunk *chunk;
  	MemoryContext per_tuple_context;
  	bool		local_estate = false;
  	Relation	rel = NULL;
  	TriggerDesc *trigdesc = NULL;
  	FmgrInfo   *finfo = NULL;
  	Instrumentation *instr = NULL;
  
  	/* Make a local EState if need be */
  	if (estate == NULL)
  	{
  		estate = CreateExecutorState();
  		local_estate = true;
  	}
  
  	/* Make a per-tuple memory context for trigger function calls */
  	per_tuple_context =
  		AllocSetContextCreate(CurrentMemoryContext,
  							  "AfterTriggerTupleContext",
  							  ALLOCSET_DEFAULT_MINSIZE,
  							  ALLOCSET_DEFAULT_INITSIZE,
  							  ALLOCSET_DEFAULT_MAXSIZE);
  
  	for_each_chunk(chunk, *events)
  	{
  		AfterTriggerEvent event;
  		bool		all_fired_in_chunk = true;
  
  		for_each_event(event, chunk)
  		{
  			AfterTriggerShared evtshared = GetTriggerSharedData(event);
  
  			/*
  			 * Is it one for me to fire?
  			 */
  			if ((event->ate_flags & AFTER_TRIGGER_IN_PROGRESS) &&
  				evtshared->ats_firing_id == firing_id)
  			{
  				/*
  				 * So let's fire it... but first, find the correct relation if
  				 * this is not the same relation as before.
  				 */
  				if (rel == NULL || RelationGetRelid(rel) != evtshared->ats_relid)
  				{
  					ResultRelInfo *rInfo;
  
  					rInfo = ExecGetTriggerResultRel(estate, evtshared->ats_relid);
  					rel = rInfo->ri_RelationDesc;
  					trigdesc = rInfo->ri_TrigDesc;
  					finfo = rInfo->ri_TrigFunctions;
  					instr = rInfo->ri_TrigInstrument;
  					if (trigdesc == NULL)		/* should not happen */
  						elog(ERROR, "relation %u has no triggers",
  							 evtshared->ats_relid);
  				}
  
  				/*
  				 * Fire it.  Note that the AFTER_TRIGGER_IN_PROGRESS flag is
  				 * still set, so recursive examinations of the event list
  				 * won't try to re-fire it.
  				 */
  				AfterTriggerExecute(event, rel, trigdesc, finfo, instr,
  									per_tuple_context);
  
  				/*
  				 * Mark the event as done.
  				 */
  				event->ate_flags &= ~AFTER_TRIGGER_IN_PROGRESS;
  				event->ate_flags |= AFTER_TRIGGER_DONE;
  			}
  			else if (!(event->ate_flags & AFTER_TRIGGER_DONE))
  			{
  				/* something remains to be done */
  				all_fired = all_fired_in_chunk = false;
  			}
  		}
  
  		/* Clear the chunk if delete_ok and nothing left of interest */
  		if (delete_ok && all_fired_in_chunk)
  		{
  			chunk->freeptr = CHUNK_DATA_START(chunk);
  			chunk->endfree = chunk->endptr;
  
  			/*
  			 * If it's last chunk, must sync event list's tailfree too.  Note
  			 * that delete_ok must NOT be passed as true if there could be
  			 * additional AfterTriggerEventList values pointing at this event
  			 * list, since we'd fail to fix their copies of tailfree.
  			 */
  			if (chunk == events->tail)
  				events->tailfree = chunk->freeptr;
  		}
  	}
  
  	/* Release working resources */
  	MemoryContextDelete(per_tuple_context);
  
  	if (local_estate)
  	{
  		ListCell   *l;
  
  		foreach(l, estate->es_trig_target_relations)
  		{
  			ResultRelInfo *resultRelInfo = (ResultRelInfo *) lfirst(l);
  
  			/* Close indices and then the relation itself */
  			ExecCloseIndices(resultRelInfo);
  			heap_close(resultRelInfo->ri_RelationDesc, NoLock);
  		}
  		FreeExecutorState(estate);
  	}
  
  	return all_fired;
  }
  
  
  /* ----------
   * AfterTriggerBeginXact()
   *
   *	Called at transaction start (either BEGIN or implicit for single
   *	statement outside of transaction block).
   * ----------
   */
  void
  AfterTriggerBeginXact(void)
  {
  	Assert(afterTriggers == NULL);
  
  	/*
  	 * Build empty after-trigger state structure
  	 */
  	afterTriggers = (AfterTriggers)
  		MemoryContextAlloc(TopTransactionContext,
  						   sizeof(AfterTriggersData));
  
  	afterTriggers->firing_counter = (CommandId) 1;		/* mustn't be 0 */
  	afterTriggers->state = SetConstraintStateCreate(8);
  	afterTriggers->events.head = NULL;
  	afterTriggers->events.tail = NULL;
  	afterTriggers->events.tailfree = NULL;
  	afterTriggers->query_depth = -1;
  
  	/* We initialize the query stack to a reasonable size */
  	afterTriggers->query_stack = (AfterTriggerEventList *)
  		MemoryContextAlloc(TopTransactionContext,
  						   8 * sizeof(AfterTriggerEventList));
  	afterTriggers->maxquerydepth = 8;
  
  	/* Context for events is created only when needed */
  	afterTriggers->event_cxt = NULL;
  
  	/* Subtransaction stack is empty until/unless needed */
  	afterTriggers->state_stack = NULL;
  	afterTriggers->events_stack = NULL;
  	afterTriggers->depth_stack = NULL;
  	afterTriggers->firing_stack = NULL;
  	afterTriggers->maxtransdepth = 0;
  }
  
  
  /* ----------
   * AfterTriggerBeginQuery()
   *
   *	Called just before we start processing a single query within a
   *	transaction (or subtransaction).  Set up to record AFTER trigger
   *	events queued by the query.  Note that it is allowed to have
   *	nested queries within a (sub)transaction.
   * ----------
   */
  void
  AfterTriggerBeginQuery(void)
  {
  	AfterTriggerEventList *events;
  
  	/* Must be inside a transaction */
  	Assert(afterTriggers != NULL);
  
  	/* Increase the query stack depth */
  	afterTriggers->query_depth++;
  
  	/*
  	 * Allocate more space in the query stack if needed.
  	 */
  	if (afterTriggers->query_depth >= afterTriggers->maxquerydepth)
  	{
  		/* repalloc will keep the stack in the same context */
  		int			new_alloc = afterTriggers->maxquerydepth * 2;
  
  		afterTriggers->query_stack = (AfterTriggerEventList *)
  			repalloc(afterTriggers->query_stack,
  					 new_alloc * sizeof(AfterTriggerEventList));
  		afterTriggers->maxquerydepth = new_alloc;
  	}
  
  	/* Initialize this query's list to empty */
  	events = &afterTriggers->query_stack[afterTriggers->query_depth];
  	events->head = NULL;
  	events->tail = NULL;
  	events->tailfree = NULL;
  }
  
  
  /* ----------
   * AfterTriggerEndQuery()
   *
   *	Called after one query has been completely processed. At this time
   *	we invoke all AFTER IMMEDIATE trigger events queued by the query, and
   *	transfer deferred trigger events to the global deferred-trigger list.
   *
   *	Note that this must be called BEFORE closing down the executor
   *	with ExecutorEnd, because we make use of the EState's info about
   *	target relations.  Normally it is called from ExecutorFinish.
   * ----------
   */
  void
  AfterTriggerEndQuery(EState *estate)
  {
  	AfterTriggerEventList *events;
  
  	/* Must be inside a transaction */
  	Assert(afterTriggers != NULL);
  
  	/* Must be inside a query, too */
  	Assert(afterTriggers->query_depth >= 0);
  
  	/*
  	 * Process all immediate-mode triggers queued by the query, and move the
  	 * deferred ones to the main list of deferred events.
  	 *
  	 * Notice that we decide which ones will be fired, and put the deferred
  	 * ones on the main list, before anything is actually fired.  This ensures
  	 * reasonably sane behavior if a trigger function does SET CONSTRAINTS ...
  	 * IMMEDIATE: all events we have decided to defer will be available for it
  	 * to fire.
  	 *
  	 * We loop in case a trigger queues more events at the same query level.
  	 * Ordinary trigger functions, including all PL/pgSQL trigger functions,
  	 * will instead fire any triggers in a dedicated query level.  Foreign key
  	 * enforcement triggers do add to the current query level, thanks to their
  	 * passing fire_triggers = false to SPI_execute_snapshot().  Other
  	 * C-language triggers might do likewise.
  	 *
  	 * If we find no firable events, we don't have to increment
  	 * firing_counter.
  	 */
  	events = &afterTriggers->query_stack[afterTriggers->query_depth];
  
  	for (;;)
  	{
  		if (afterTriggerMarkEvents(events, &afterTriggers->events, true))
  		{
  			CommandId	firing_id = afterTriggers->firing_counter++;
  			AfterTriggerEventChunk *oldtail = events->tail;
  
  			if (afterTriggerInvokeEvents(events, firing_id, estate, false))
  				break;			/* all fired */
  
  			/*
  			 * Firing a trigger could result in query_stack being repalloc'd,
  			 * so we must recalculate ptr after each afterTriggerInvokeEvents
  			 * call.  Furthermore, it's unsafe to pass delete_ok = true here,
  			 * because that could cause afterTriggerInvokeEvents to try to
  			 * access *events after the stack has been repalloc'd.
  			 */
  			events = &afterTriggers->query_stack[afterTriggers->query_depth];
  
  			/*
  			 * We'll need to scan the events list again.  To reduce the cost
  			 * of doing so, get rid of completely-fired chunks.  We know that
  			 * all events were marked IN_PROGRESS or DONE at the conclusion of
  			 * afterTriggerMarkEvents, so any still-interesting events must
  			 * have been added after that, and so must be in the chunk that
  			 * was then the tail chunk, or in later chunks.  So, zap all
  			 * chunks before oldtail.  This is approximately the same set of
  			 * events we would have gotten rid of by passing delete_ok = true.
  			 */
  			Assert(oldtail != NULL);
  			while (events->head != oldtail)
  				afterTriggerDeleteHeadEventChunk(events);
  		}
  		else
  			break;
  	}
  
  	/* Release query-local storage for events */
  	afterTriggerFreeEventList(&afterTriggers->query_stack[afterTriggers->query_depth]);
  
  	afterTriggers->query_depth--;
  }
  
  
  /* ----------
   * AfterTriggerFireDeferred()
   *
   *	Called just before the current transaction is committed. At this
   *	time we invoke all pending DEFERRED triggers.
   *
   *	It is possible for other modules to queue additional deferred triggers
   *	during pre-commit processing; therefore xact.c may have to call this
   *	multiple times.
   * ----------
   */
  void
  AfterTriggerFireDeferred(void)
  {
  	AfterTriggerEventList *events;
  	bool		snap_pushed = false;
  
  	/* Must be inside a transaction */
  	Assert(afterTriggers != NULL);
  
  	/* ... but not inside a query */
  	Assert(afterTriggers->query_depth == -1);
  
  	/*
  	 * If there are any triggers to fire, make sure we have set a snapshot for
  	 * them to use.  (Since PortalRunUtility doesn't set a snap for COMMIT, we
  	 * can't assume ActiveSnapshot is valid on entry.)
  	 */
  	events = &afterTriggers->events;
  	if (events->head != NULL)
  	{
  		PushActiveSnapshot(GetTransactionSnapshot());
  		snap_pushed = true;
  	}
  
  	/*
  	 * Run all the remaining triggers.  Loop until they are all gone, in case
  	 * some trigger queues more for us to do.
  	 */
  	while (afterTriggerMarkEvents(events, NULL, false))
  	{
  		CommandId	firing_id = afterTriggers->firing_counter++;
  
  		if (afterTriggerInvokeEvents(events, firing_id, NULL, true))
  			break;				/* all fired */
  	}
  
  	/*
  	 * We don't bother freeing the event list, since it will go away anyway
  	 * (and more efficiently than via pfree) in AfterTriggerEndXact.
  	 */
  
  	if (snap_pushed)
  		PopActiveSnapshot();
  }
  
  
  /* ----------
   * AfterTriggerEndXact()
   *
   *	The current transaction is finishing.
   *
   *	Any unfired triggers are canceled so we simply throw
   *	away anything we know.
   *
   *	Note: it is possible for this to be called repeatedly in case of
   *	error during transaction abort; therefore, do not complain if
   *	already closed down.
   * ----------
   */
  void
  AfterTriggerEndXact(bool isCommit)
  {
  	/*
  	 * Forget everything we know about AFTER triggers.
  	 *
  	 * Since all the info is in TopTransactionContext or children thereof, we
  	 * don't really need to do anything to reclaim memory.  However, the
  	 * pending-events list could be large, and so it's useful to discard it as
  	 * soon as possible --- especially if we are aborting because we ran out
  	 * of memory for the list!
  	 */
  	if (afterTriggers && afterTriggers->event_cxt)
  		MemoryContextDelete(afterTriggers->event_cxt);
  
  	afterTriggers = NULL;
  }
  
  /*
   * AfterTriggerBeginSubXact()
   *
   *	Start a subtransaction.
   */
  void
  AfterTriggerBeginSubXact(void)
  {
  	int			my_level = GetCurrentTransactionNestLevel();
  
  	/*
  	 * Ignore call if the transaction is in aborted state.  (Probably
  	 * shouldn't happen?)
  	 */
  	if (afterTriggers == NULL)
  		return;
  
  	/*
  	 * Allocate more space in the stacks if needed.  (Note: because the
  	 * minimum nest level of a subtransaction is 2, we waste the first couple
  	 * entries of each array; not worth the notational effort to avoid it.)
  	 */
  	while (my_level >= afterTriggers->maxtransdepth)
  	{
  		if (afterTriggers->maxtransdepth == 0)
  		{
  			MemoryContext old_cxt;
  
  			old_cxt = MemoryContextSwitchTo(TopTransactionContext);
  
  #define DEFTRIG_INITALLOC 8
  			afterTriggers->state_stack = (SetConstraintState *)
  				palloc(DEFTRIG_INITALLOC * sizeof(SetConstraintState));
  			afterTriggers->events_stack = (AfterTriggerEventList *)
  				palloc(DEFTRIG_INITALLOC * sizeof(AfterTriggerEventList));
  			afterTriggers->depth_stack = (int *)
  				palloc(DEFTRIG_INITALLOC * sizeof(int));
  			afterTriggers->firing_stack = (CommandId *)
  				palloc(DEFTRIG_INITALLOC * sizeof(CommandId));
  			afterTriggers->maxtransdepth = DEFTRIG_INITALLOC;
  
  			MemoryContextSwitchTo(old_cxt);
  		}
  		else
  		{
  			/* repalloc will keep the stacks in the same context */
  			int			new_alloc = afterTriggers->maxtransdepth * 2;
  
  			afterTriggers->state_stack = (SetConstraintState *)
  				repalloc(afterTriggers->state_stack,
  						 new_alloc * sizeof(SetConstraintState));
  			afterTriggers->events_stack = (AfterTriggerEventList *)
  				repalloc(afterTriggers->events_stack,
  						 new_alloc * sizeof(AfterTriggerEventList));
  			afterTriggers->depth_stack = (int *)
  				repalloc(afterTriggers->depth_stack,
  						 new_alloc * sizeof(int));
  			afterTriggers->firing_stack = (CommandId *)
  				repalloc(afterTriggers->firing_stack,
  						 new_alloc * sizeof(CommandId));
  			afterTriggers->maxtransdepth = new_alloc;
  		}
  	}
  
  	/*
  	 * Push the current information into the stack.  The SET CONSTRAINTS state
  	 * is not saved until/unless changed.  Likewise, we don't make a
  	 * per-subtransaction event context until needed.
  	 */
  	afterTriggers->state_stack[my_level] = NULL;
  	afterTriggers->events_stack[my_level] = afterTriggers->events;
  	afterTriggers->depth_stack[my_level] = afterTriggers->query_depth;
  	afterTriggers->firing_stack[my_level] = afterTriggers->firing_counter;
  }
  
  /*
   * AfterTriggerEndSubXact()
   *
   *	The current subtransaction is ending.
   */
  void
  AfterTriggerEndSubXact(bool isCommit)
  {
  	int			my_level = GetCurrentTransactionNestLevel();
  	SetConstraintState state;
  	AfterTriggerEvent event;
  	AfterTriggerEventChunk *chunk;
  	CommandId	subxact_firing_id;
  
  	/*
  	 * Ignore call if the transaction is in aborted state.  (Probably
  	 * unneeded)
  	 */
  	if (afterTriggers == NULL)
  		return;
  
  	/*
  	 * Pop the prior state if needed.
  	 */
  	if (isCommit)
  	{
  		Assert(my_level < afterTriggers->maxtransdepth);
  		/* If we saved a prior state, we don't need it anymore */
  		state = afterTriggers->state_stack[my_level];
  		if (state != NULL)
  			pfree(state);
  		/* this avoids double pfree if error later: */
  		afterTriggers->state_stack[my_level] = NULL;
  		Assert(afterTriggers->query_depth ==
  			   afterTriggers->depth_stack[my_level]);
  	}
  	else
  	{
  		/*
  		 * Aborting.  It is possible subxact start failed before calling
  		 * AfterTriggerBeginSubXact, in which case we mustn't risk touching
  		 * stack levels that aren't there.
  		 */
  		if (my_level >= afterTriggers->maxtransdepth)
  			return;
  
  		/*
  		 * Release any event lists from queries being aborted, and restore
  		 * query_depth to its pre-subxact value.
  		 */
  		while (afterTriggers->query_depth > afterTriggers->depth_stack[my_level])
  		{
  			afterTriggerFreeEventList(&afterTriggers->query_stack[afterTriggers->query_depth]);
  			afterTriggers->query_depth--;
  		}
  		Assert(afterTriggers->query_depth ==
  			   afterTriggers->depth_stack[my_level]);
  
  		/*
  		 * Restore the global deferred-event list to its former length,
  		 * discarding any events queued by the subxact.
  		 */
  		afterTriggerRestoreEventList(&afterTriggers->events,
  									 &afterTriggers->events_stack[my_level]);
  
  		/*
  		 * Restore the trigger state.  If the saved state is NULL, then this
  		 * subxact didn't save it, so it doesn't need restoring.
  		 */
  		state = afterTriggers->state_stack[my_level];
  		if (state != NULL)
  		{
  			pfree(afterTriggers->state);
  			afterTriggers->state = state;
  		}
  		/* this avoids double pfree if error later: */
  		afterTriggers->state_stack[my_level] = NULL;
  
  		/*
  		 * Scan for any remaining deferred events that were marked DONE or IN
  		 * PROGRESS by this subxact or a child, and un-mark them. We can
  		 * recognize such events because they have a firing ID greater than or
  		 * equal to the firing_counter value we saved at subtransaction start.
  		 * (This essentially assumes that the current subxact includes all
  		 * subxacts started after it.)
  		 */
  		subxact_firing_id = afterTriggers->firing_stack[my_level];
  		for_each_event_chunk(event, chunk, afterTriggers->events)
  		{
  			AfterTriggerShared evtshared = GetTriggerSharedData(event);
  
  			if (event->ate_flags &
  				(AFTER_TRIGGER_DONE | AFTER_TRIGGER_IN_PROGRESS))
  			{
  				if (evtshared->ats_firing_id >= subxact_firing_id)
  					event->ate_flags &=
  						~(AFTER_TRIGGER_DONE | AFTER_TRIGGER_IN_PROGRESS);
  			}
  		}
  	}
  }
  
  /*
   * Create an empty SetConstraintState with room for numalloc trigstates
   */
  static SetConstraintState
  SetConstraintStateCreate(int numalloc)
  {
  	SetConstraintState state;
  
  	/* Behave sanely with numalloc == 0 */
  	if (numalloc <= 0)
  		numalloc = 1;
  
  	/*
  	 * We assume that zeroing will correctly initialize the state values.
  	 */
  	state = (SetConstraintState)
  		MemoryContextAllocZero(TopTransactionContext,
  							   sizeof(SetConstraintStateData) +
  						   (numalloc - 1) *sizeof(SetConstraintTriggerData));
  
  	state->numalloc = numalloc;
  
  	return state;
  }
  
  /*
   * Copy a SetConstraintState
   */
  static SetConstraintState
  SetConstraintStateCopy(SetConstraintState origstate)
  {
  	SetConstraintState state;
  
  	state = SetConstraintStateCreate(origstate->numstates);
  
  	state->all_isset = origstate->all_isset;
  	state->all_isdeferred = origstate->all_isdeferred;
  	state->numstates = origstate->numstates;
  	memcpy(state->trigstates, origstate->trigstates,
  		   origstate->numstates * sizeof(SetConstraintTriggerData));
  
  	return state;
  }
  
  /*
   * Add a per-trigger item to a SetConstraintState.  Returns possibly-changed
   * pointer to the state object (it will change if we have to repalloc).
   */
  static SetConstraintState
  SetConstraintStateAddItem(SetConstraintState state,
  						  Oid tgoid, bool tgisdeferred)
  {
  	if (state->numstates >= state->numalloc)
  	{
  		int			newalloc = state->numalloc * 2;
  
  		newalloc = Max(newalloc, 8);	/* in case original has size 0 */
  		state = (SetConstraintState)
  			repalloc(state,
  					 sizeof(SetConstraintStateData) +
  					 (newalloc - 1) *sizeof(SetConstraintTriggerData));
  		state->numalloc = newalloc;
  		Assert(state->numstates < state->numalloc);
  	}
  
  	state->trigstates[state->numstates].sct_tgoid = tgoid;
  	state->trigstates[state->numstates].sct_tgisdeferred = tgisdeferred;
  	state->numstates++;
  
  	return state;
  }
  
  /* ----------
   * AfterTriggerSetState()
   *
   *	Execute the SET CONSTRAINTS ... utility command.
   * ----------
   */
  void
  AfterTriggerSetState(ConstraintsSetStmt *stmt)
  {
  	int			my_level = GetCurrentTransactionNestLevel();
  
  	/*
  	 * Ignore call if we aren't in a transaction.  (Shouldn't happen?)
  	 */
  	if (afterTriggers == NULL)
  		return;
  
  	/*
  	 * If in a subtransaction, and we didn't save the current state already,
  	 * save it so it can be restored if the subtransaction aborts.
  	 */
  	if (my_level > 1 &&
  		afterTriggers->state_stack[my_level] == NULL)
  	{
  		afterTriggers->state_stack[my_level] =
  			SetConstraintStateCopy(afterTriggers->state);
  	}
  
  	/*
  	 * Handle SET CONSTRAINTS ALL ...
  	 */
  	if (stmt->constraints == NIL)
  	{
  		/*
  		 * Forget any previous SET CONSTRAINTS commands in this transaction.
  		 */
  		afterTriggers->state->numstates = 0;
  
  		/*
  		 * Set the per-transaction ALL state to known.
  		 */
  		afterTriggers->state->all_isset = true;
  		afterTriggers->state->all_isdeferred = stmt->deferred;
  	}
  	else
  	{
  		Relation	conrel;
  		Relation	tgrel;
  		List	   *conoidlist = NIL;
  		List	   *tgoidlist = NIL;
  		ListCell   *lc;
  
  		/*
  		 * Handle SET CONSTRAINTS constraint-name [, ...]
  		 *
  		 * First, identify all the named constraints and make a list of their
  		 * OIDs.  Since, unlike the SQL spec, we allow multiple constraints of
  		 * the same name within a schema, the specifications are not
  		 * necessarily unique.  Our strategy is to target all matching
  		 * constraints within the first search-path schema that has any
  		 * matches, but disregard matches in schemas beyond the first match.
  		 * (This is a bit odd but it's the historical behavior.)
  		 */
  		conrel = heap_open(ConstraintRelationId, AccessShareLock);
  
  		foreach(lc, stmt->constraints)
  		{
  			RangeVar   *constraint = lfirst(lc);
  			bool		found;
  			List	   *namespacelist;
  			ListCell   *nslc;
  
  			if (constraint->catalogname)
  			{
  				if (strcmp(constraint->catalogname, get_database_name(MyDatabaseId)) != 0)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("cross-database references are not implemented: \"%s.%s.%s\"",
  							 constraint->catalogname, constraint->schemaname,
  									constraint->relname)));
  			}
  
  			/*
  			 * If we're given the schema name with the constraint, look only
  			 * in that schema.  If given a bare constraint name, use the
  			 * search path to find the first matching constraint.
  			 */
  			if (constraint->schemaname)
  			{
  				Oid			namespaceId = LookupExplicitNamespace(constraint->schemaname);
  
  				namespacelist = list_make1_oid(namespaceId);
  			}
  			else
  			{
  				namespacelist = fetch_search_path(true);
  			}
  
  			found = false;
  			foreach(nslc, namespacelist)
  			{
  				Oid			namespaceId = lfirst_oid(nslc);
  				SysScanDesc conscan;
  				ScanKeyData skey[2];
  				HeapTuple	tup;
  
  				ScanKeyInit(&skey[0],
  							Anum_pg_constraint_conname,
  							BTEqualStrategyNumber, F_NAMEEQ,
  							CStringGetDatum(constraint->relname));
  				ScanKeyInit(&skey[1],
  							Anum_pg_constraint_connamespace,
  							BTEqualStrategyNumber, F_OIDEQ,
  							ObjectIdGetDatum(namespaceId));
  
  				conscan = systable_beginscan(conrel, ConstraintNameNspIndexId,
  											 true, SnapshotNow, 2, skey);
  
  				while (HeapTupleIsValid(tup = systable_getnext(conscan)))
  				{
  					Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tup);
  
  					if (con->condeferrable)
  						conoidlist = lappend_oid(conoidlist,
  												 HeapTupleGetOid(tup));
  					else if (stmt->deferred)
  						ereport(ERROR,
  								(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  								 errmsg("constraint \"%s\" is not deferrable",
  										constraint->relname)));
  					found = true;
  				}
  
  				systable_endscan(conscan);
  
  				/*
  				 * Once we've found a matching constraint we do not search
  				 * later parts of the search path.
  				 */
  				if (found)
  					break;
  			}
  
  			list_free(namespacelist);
  
  			/*
  			 * Not found ?
  			 */
  			if (!found)
  				ereport(ERROR,
  						(errcode(ERRCODE_UNDEFINED_OBJECT),
  						 errmsg("constraint \"%s\" does not exist",
  								constraint->relname)));
  		}
  
  		heap_close(conrel, AccessShareLock);
  
  		/*
  		 * Now, locate the trigger(s) implementing each of these constraints,
  		 * and make a list of their OIDs.
  		 */
  		tgrel = heap_open(TriggerRelationId, AccessShareLock);
  
  		foreach(lc, conoidlist)
  		{
  			Oid			conoid = lfirst_oid(lc);
  			bool		found;
  			ScanKeyData skey;
  			SysScanDesc tgscan;
  			HeapTuple	htup;
  
  			found = false;
  
  			ScanKeyInit(&skey,
  						Anum_pg_trigger_tgconstraint,
  						BTEqualStrategyNumber, F_OIDEQ,
  						ObjectIdGetDatum(conoid));
  
  			tgscan = systable_beginscan(tgrel, TriggerConstraintIndexId, true,
  										SnapshotNow, 1, &skey);
  
  			while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
  			{
  				Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);
  
  				/*
  				 * Silently skip triggers that are marked as non-deferrable in
  				 * pg_trigger.  This is not an error condition, since a
  				 * deferrable RI constraint may have some non-deferrable
  				 * actions.
  				 */
  				if (pg_trigger->tgdeferrable)
  					tgoidlist = lappend_oid(tgoidlist,
  											HeapTupleGetOid(htup));
  
  				found = true;
  			}
  
  			systable_endscan(tgscan);
  
  			/* Safety check: a deferrable constraint should have triggers */
  			if (!found)
  				elog(ERROR, "no triggers found for constraint with OID %u",
  					 conoid);
  		}
  
  		heap_close(tgrel, AccessShareLock);
  
  		/*
  		 * Now we can set the trigger states of individual triggers for this
  		 * xact.
  		 */
  		foreach(lc, tgoidlist)
  		{
  			Oid			tgoid = lfirst_oid(lc);
  			SetConstraintState state = afterTriggers->state;
  			bool		found = false;
  			int			i;
  
  			for (i = 0; i < state->numstates; i++)
  			{
  				if (state->trigstates[i].sct_tgoid == tgoid)
  				{
  					state->trigstates[i].sct_tgisdeferred = stmt->deferred;
  					found = true;
  					break;
  				}
  			}
  			if (!found)
  			{
  				afterTriggers->state =
  					SetConstraintStateAddItem(state, tgoid, stmt->deferred);
  			}
  		}
  	}
  
  	/*
  	 * SQL99 requires that when a constraint is set to IMMEDIATE, any deferred
  	 * checks against that constraint must be made when the SET CONSTRAINTS
  	 * command is executed -- i.e. the effects of the SET CONSTRAINTS command
  	 * apply retroactively.  We've updated the constraints state, so scan the
  	 * list of previously deferred events to fire any that have now become
  	 * immediate.
  	 *
  	 * Obviously, if this was SET ... DEFERRED then it can't have converted
  	 * any unfired events to immediate, so we need do nothing in that case.
  	 */
  	if (!stmt->deferred)
  	{
  		AfterTriggerEventList *events = &afterTriggers->events;
  		bool		snapshot_set = false;
  
  		while (afterTriggerMarkEvents(events, NULL, true))
  		{
  			CommandId	firing_id = afterTriggers->firing_counter++;
  
  			/*
  			 * Make sure a snapshot has been established in case trigger
  			 * functions need one.  Note that we avoid setting a snapshot if
  			 * we don't find at least one trigger that has to be fired now.
  			 * This is so that BEGIN; SET CONSTRAINTS ...; SET TRANSACTION
  			 * ISOLATION LEVEL SERIALIZABLE; ... works properly.  (If we are
  			 * at the start of a transaction it's not possible for any trigger
  			 * events to be queued yet.)
  			 */
  			if (!snapshot_set)
  			{
  				PushActiveSnapshot(GetTransactionSnapshot());
  				snapshot_set = true;
  			}
  
  			/*
  			 * We can delete fired events if we are at top transaction level,
  			 * but we'd better not if inside a subtransaction, since the
  			 * subtransaction could later get rolled back.
  			 */
  			if (afterTriggerInvokeEvents(events, firing_id, NULL,
  										 !IsSubTransaction()))
  				break;			/* all fired */
  		}
  
  		if (snapshot_set)
  			PopActiveSnapshot();
  	}
  }
  
  /* ----------
   * AfterTriggerPendingOnRel()
   *		Test to see if there are any pending after-trigger events for rel.
   *
   * This is used by TRUNCATE, CLUSTER, ALTER TABLE, etc to detect whether
   * it is unsafe to perform major surgery on a relation.  Note that only
   * local pending events are examined.  We assume that having exclusive lock
   * on a rel guarantees there are no unserviced events in other backends ---
   * but having a lock does not prevent there being such events in our own.
   *
   * In some scenarios it'd be reasonable to remove pending events (more
   * specifically, mark them DONE by the current subxact) but without a lot
   * of knowledge of the trigger semantics we can't do this in general.
   * ----------
   */
  bool
  AfterTriggerPendingOnRel(Oid relid)
  {
  	AfterTriggerEvent event;
  	AfterTriggerEventChunk *chunk;
  	int			depth;
  
  	/* No-op if we aren't in a transaction.  (Shouldn't happen?) */
  	if (afterTriggers == NULL)
  		return false;
  
  	/* Scan queued events */
  	for_each_event_chunk(event, chunk, afterTriggers->events)
  	{
  		AfterTriggerShared evtshared = GetTriggerSharedData(event);
  
  		/*
  		 * We can ignore completed events.  (Even if a DONE flag is rolled
  		 * back by subxact abort, it's OK because the effects of the TRUNCATE
  		 * or whatever must get rolled back too.)
  		 */
  		if (event->ate_flags & AFTER_TRIGGER_DONE)
  			continue;
  
  		if (evtshared->ats_relid == relid)
  			return true;
  	}
  
  	/*
  	 * Also scan events queued by incomplete queries.  This could only matter
  	 * if TRUNCATE/etc is executed by a function or trigger within an updating
  	 * query on the same relation, which is pretty perverse, but let's check.
  	 */
  	for (depth = 0; depth <= afterTriggers->query_depth; depth++)
  	{
  		for_each_event_chunk(event, chunk, afterTriggers->query_stack[depth])
  		{
  			AfterTriggerShared evtshared = GetTriggerSharedData(event);
  
  			if (event->ate_flags & AFTER_TRIGGER_DONE)
  				continue;
  
  			if (evtshared->ats_relid == relid)
  				return true;
  		}
  	}
  
  	return false;
  }
  
  
  /* ----------
   * AfterTriggerSaveEvent()
   *
   *	Called by ExecA[RS]...Triggers() to queue up the triggers that should
   *	be fired for an event.
   *
   *	NOTE: this is called whenever there are any triggers associated with
   *	the event (even if they are disabled).  This function decides which
   *	triggers actually need to be queued.
   * ----------
   */
  static void
  AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
  					  int event, bool row_trigger,
  					  HeapTuple oldtup, HeapTuple newtup,
  					  List *recheckIndexes, Bitmapset *modifiedCols)
  {
  	Relation	rel = relinfo->ri_RelationDesc;
  	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  	AfterTriggerEventData new_event;
  	AfterTriggerSharedData new_shared;
  	int			tgtype_event;
  	int			tgtype_level;
  	int			i;
  
  	/*
  	 * Check state.  We use normal tests not Asserts because it is possible to
  	 * reach here in the wrong state given misconfigured RI triggers, in
  	 * particular deferring a cascade action trigger.
  	 */
  	if (afterTriggers == NULL)
  		elog(ERROR, "AfterTriggerSaveEvent() called outside of transaction");
  	if (afterTriggers->query_depth < 0)
  		elog(ERROR, "AfterTriggerSaveEvent() called outside of query");
  
  	/*
  	 * Validate the event code and collect the associated tuple CTIDs.
  	 *
  	 * The event code will be used both as a bitmask and an array offset, so
  	 * validation is important to make sure we don't walk off the edge of our
  	 * arrays.
  	 */
  	new_event.ate_flags = 0;
  	switch (event)
  	{
  		case TRIGGER_EVENT_INSERT:
  			tgtype_event = TRIGGER_TYPE_INSERT;
  			if (row_trigger)
  			{
  				Assert(oldtup == NULL);
  				Assert(newtup != NULL);
  				ItemPointerCopy(&(newtup->t_self), &(new_event.ate_ctid1));
  				ItemPointerSetInvalid(&(new_event.ate_ctid2));
  			}
  			else
  			{
  				Assert(oldtup == NULL);
  				Assert(newtup == NULL);
  				ItemPointerSetInvalid(&(new_event.ate_ctid1));
  				ItemPointerSetInvalid(&(new_event.ate_ctid2));
  			}
  			break;
  		case TRIGGER_EVENT_DELETE:
  			tgtype_event = TRIGGER_TYPE_DELETE;
  			if (row_trigger)
  			{
  				Assert(oldtup != NULL);
  				Assert(newtup == NULL);
  				ItemPointerCopy(&(oldtup->t_self), &(new_event.ate_ctid1));
  				ItemPointerSetInvalid(&(new_event.ate_ctid2));
  			}
  			else
  			{
  				Assert(oldtup == NULL);
  				Assert(newtup == NULL);
  				ItemPointerSetInvalid(&(new_event.ate_ctid1));
  				ItemPointerSetInvalid(&(new_event.ate_ctid2));
  			}
  			break;
  		case TRIGGER_EVENT_UPDATE:
  			tgtype_event = TRIGGER_TYPE_UPDATE;
  			if (row_trigger)
  			{
  				Assert(oldtup != NULL);
  				Assert(newtup != NULL);
  				ItemPointerCopy(&(oldtup->t_self), &(new_event.ate_ctid1));
  				ItemPointerCopy(&(newtup->t_self), &(new_event.ate_ctid2));
  				new_event.ate_flags |= AFTER_TRIGGER_2CTIDS;
  			}
  			else
  			{
  				Assert(oldtup == NULL);
  				Assert(newtup == NULL);
  				ItemPointerSetInvalid(&(new_event.ate_ctid1));
  				ItemPointerSetInvalid(&(new_event.ate_ctid2));
  			}
  			break;
  		case TRIGGER_EVENT_TRUNCATE:
  			tgtype_event = TRIGGER_TYPE_TRUNCATE;
  			Assert(oldtup == NULL);
  			Assert(newtup == NULL);
  			ItemPointerSetInvalid(&(new_event.ate_ctid1));
  			ItemPointerSetInvalid(&(new_event.ate_ctid2));
  			break;
  		default:
  			elog(ERROR, "invalid after-trigger event code: %d", event);
  			tgtype_event = 0;	/* keep compiler quiet */
  			break;
  	}
  
  	tgtype_level = (row_trigger ? TRIGGER_TYPE_ROW : TRIGGER_TYPE_STATEMENT);
  
  	for (i = 0; i < trigdesc->numtriggers; i++)
  	{
  		Trigger    *trigger = &trigdesc->triggers[i];
  
  		if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
  								  tgtype_level,
  								  TRIGGER_TYPE_AFTER,
  								  tgtype_event))
  			continue;
  		if (!TriggerEnabled(estate, relinfo, trigger, event,
  							modifiedCols, oldtup, newtup))
  			continue;
  
  		/*
  		 * If this is an UPDATE of a PK table or FK table that does not change
  		 * the PK or FK respectively, we can skip queuing the event: there is
  		 * no need to fire the trigger.
  		 */
  		if (TRIGGER_FIRED_BY_UPDATE(event))
  		{
  			switch (RI_FKey_trigger_type(trigger->tgfoid))
  			{
  				case RI_TRIGGER_PK:
  					/* Update on PK table */
  					if (RI_FKey_keyequal_upd_pk(trigger, rel, oldtup, newtup))
  					{
  						/* key unchanged, so skip queuing this event */
  						continue;
  					}
  					break;
  
  				case RI_TRIGGER_FK:
  
  					/*
  					 * Update on FK table
  					 *
  					 * There is one exception when updating FK tables: if the
  					 * updated row was inserted by our own transaction and the
  					 * FK is deferred, we still need to fire the trigger. This
  					 * is because our UPDATE will invalidate the INSERT so the
  					 * end-of-transaction INSERT RI trigger will not do
  					 * anything, so we have to do the check for the UPDATE
  					 * anyway.
  					 */
  					if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(oldtup->t_data)) &&
  						RI_FKey_keyequal_upd_fk(trigger, rel, oldtup, newtup))
  					{
  						continue;
  					}
  					break;
  
  				case RI_TRIGGER_NONE:
  					/* Not an FK trigger */
  					break;
  			}
  		}
  
  		/*
  		 * If the trigger is a deferred unique constraint check trigger, only
  		 * queue it if the unique constraint was potentially violated, which
  		 * we know from index insertion time.
  		 */
  		if (trigger->tgfoid == F_UNIQUE_KEY_RECHECK)
  		{
  			if (!list_member_oid(recheckIndexes, trigger->tgconstrindid))
  				continue;		/* Uniqueness definitely not violated */
  		}
  
  		/*
  		 * Fill in event structure and add it to the current query's queue.
  		 */
  		new_shared.ats_event =
  			(event & TRIGGER_EVENT_OPMASK) |
  			(row_trigger ? TRIGGER_EVENT_ROW : 0) |
  			(trigger->tgdeferrable ? AFTER_TRIGGER_DEFERRABLE : 0) |
  			(trigger->tginitdeferred ? AFTER_TRIGGER_INITDEFERRED : 0);
  		new_shared.ats_tgoid = trigger->tgoid;
  		new_shared.ats_relid = RelationGetRelid(rel);
  		new_shared.ats_firing_id = 0;
  
  		afterTriggerAddEvent(&afterTriggers->query_stack[afterTriggers->query_depth],
  							 &new_event, &new_shared);
  	}
  }
  
  Datum
  pg_trigger_depth(PG_FUNCTION_ARGS)
  {
  	PG_RETURN_INT32(MyTriggerDepth);
  }
  