Rewrite, normal execution vs. EXPLAIN ANALYZE

*** a/src/backend/catalog/pg_proc.c
--- b/src/backend/catalog/pg_proc.c
***************
*** 832,838 **** fmgr_sql_validator(PG_FUNCTION_ARGS)
  												  proc->proargtypes.values,
  												  proc->pronargs);
  			(void) check_sql_fn_retval(funcoid, proc->prorettype,
! 									   querytree_list,
  									   NULL, NULL);
  		}
  		else
--- 832,838 ----
  												  proc->proargtypes.values,
  												  proc->pronargs);
  			(void) check_sql_fn_retval(funcoid, proc->prorettype,
! 									   llast(querytree_list),
  									   NULL, NULL);
  		}
  		else
*** a/src/backend/executor/functions.c
--- b/src/backend/executor/functions.c
***************
*** 90,107 **** typedef struct
  	ParamListInfo paramLI;		/* Param list representing current args */
  
  	Tuplestorestate *tstore;	/* where we accumulate result tuples */
  
  	JunkFilter *junkFilter;		/* will be NULL if function returns VOID */
  
! 	/* head of linked list of execution_state records */
! 	execution_state *func_state;
  } SQLFunctionCache;
  
  typedef SQLFunctionCache *SQLFunctionCachePtr;
  
  
  /* non-export function prototypes */
! static execution_state *init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK);
  static void init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK);
--- 90,107 ----
  	ParamListInfo paramLI;		/* Param list representing current args */
  
  	Tuplestorestate *tstore;	/* where we accumulate result tuples */
+ 	Snapshot	snapshot;
  
  	JunkFilter *junkFilter;		/* will be NULL if function returns VOID */
  
! 	List *func_state;
  } SQLFunctionCache;
  
  typedef SQLFunctionCache *SQLFunctionCachePtr;
  
  
  /* non-export function prototypes */
! static List *init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK);
  static void init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK);
***************
*** 123,183 **** static void sqlfunction_destroy(DestReceiver *self);
  
  
  /* Set up the list of per-query execution_state records for a SQL function */
! static execution_state *
  init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK)
  {
! 	execution_state *firstes = NULL;
! 	execution_state *preves = NULL;
  	execution_state *lasttages = NULL;
! 	ListCell   *qtl_item;
  
! 	foreach(qtl_item, queryTree_list)
  	{
! 		Query	   *queryTree = (Query *) lfirst(qtl_item);
! 		Node	   *stmt;
! 		execution_state *newes;
  
! 		Assert(IsA(queryTree, Query));
  
! 		if (queryTree->commandType == CMD_UTILITY)
! 			stmt = queryTree->utilityStmt;
! 		else
! 			stmt = (Node *) pg_plan_query(queryTree, 0, NULL);
  
! 		/* Precheck all commands for validity in a function */
! 		if (IsA(stmt, TransactionStmt))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 			/* translator: %s is a SQL statement name */
! 					 errmsg("%s is not allowed in a SQL function",
! 							CreateCommandTag(stmt))));
  
! 		if (fcache->readonly_func && !CommandIsReadOnly(stmt))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 			/* translator: %s is a SQL statement name */
! 					 errmsg("%s is not allowed in a non-volatile function",
! 							CreateCommandTag(stmt))));
  
! 		newes = (execution_state *) palloc(sizeof(execution_state));
! 		if (preves)
! 			preves->next = newes;
! 		else
! 			firstes = newes;
  
! 		newes->next = NULL;
! 		newes->status = F_EXEC_START;
! 		newes->setsResult = false;		/* might change below */
! 		newes->lazyEval = false;	/* might change below */
! 		newes->stmt = stmt;
! 		newes->qd = NULL;
  
! 		if (queryTree->canSetTag)
! 			lasttages = newes;
  
! 		preves = newes;
  	}
  
  	/*
--- 123,200 ----
  
  
  /* Set up the list of per-query execution_state records for a SQL function */
! static List *
  init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK)
  {
! 	execution_state *firstes;
! 	execution_state *preves;
  	execution_state *lasttages = NULL;
! 	List	   *eslist;
! 	ListCell   *lc1;
! 	ListCell   *lc2;
! 	List	   *qtlist;
! 	Query	   *queryTree;
! 
! 
! 	eslist = NIL;
  
! 	foreach(lc1, queryTree_list)
  	{
! 		qtlist = (List *) lfirst(lc1);
! 		firstes = NULL;
! 		preves = NULL;
  
! 		foreach(lc2, qtlist)
! 		{
! 			Node	   *stmt;
! 			execution_state *newes;
  
! 			queryTree = (Query *) lfirst(lc2);
  
! 			Assert(IsA(queryTree, Query));
  
! 			if (queryTree->commandType == CMD_UTILITY)
! 				stmt = queryTree->utilityStmt;
! 			else
! 				stmt = (Node *) pg_plan_query(queryTree, 0, NULL);
  
! 			/* Precheck all commands for validity in a function */
! 			if (IsA(stmt, TransactionStmt))
! 				ereport(ERROR,
! 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 				/* translator: %s is a SQL statement name */
! 						 errmsg("%s is not allowed in a SQL function",
! 								CreateCommandTag(stmt))));
! 
! 			if (fcache->readonly_func && !CommandIsReadOnly(stmt))
! 				ereport(ERROR,
! 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 				/* translator: %s is a SQL statement name */
! 						 errmsg("%s is not allowed in a non-volatile function",
! 								CreateCommandTag(stmt))));
! 
! 			newes = (execution_state *) palloc(sizeof(execution_state));
! 			if (preves)
! 				preves->next = newes;
! 			else
! 				firstes = newes;
  
! 			newes->next = NULL;
! 			newes->status = F_EXEC_START;
! 			newes->setsResult = false;		/* might change below */
! 			newes->lazyEval = false;	/* might change below */
! 			newes->stmt = stmt;
! 			newes->qd = NULL;
  
! 			if (queryTree->canSetTag)
! 				lasttages = newes;
! 
! 			preves = newes;
! 		}
  
! 		eslist = lappend(eslist, firstes);
  	}
  
  	/*
***************
*** 210,216 **** init_execution_state(List *queryTree_list,
  		}
  	}
  
! 	return firstes;
  }
  
  /* Initialize the SQLFunctionCache for a SQL function */
--- 227,233 ----
  		}
  	}
  
! 	return eslist;
  }
  
  /* Initialize the SQLFunctionCache for a SQL function */
***************
*** 342,348 **** init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK)
  	 */
  	fcache->returnsTuple = check_sql_fn_retval(foid,
  											   rettype,
! 											   queryTree_list,
  											   NULL,
  											   &fcache->junkFilter);
  
--- 359,365 ----
  	 */
  	fcache->returnsTuple = check_sql_fn_retval(foid,
  											   rettype,
! 											   llast(queryTree_list),
  											   NULL,
  											   &fcache->junkFilter);
  
***************
*** 374,397 **** init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK)
  static void
  postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  {
- 	Snapshot	snapshot;
  	DestReceiver *dest;
  
  	Assert(es->qd == NULL);
  
! 	/*
! 	 * In a read-only function, use the surrounding query's snapshot;
! 	 * otherwise take a new snapshot for each query.  The snapshot should
! 	 * include a fresh command ID so that all work to date in this transaction
! 	 * is visible.
! 	 */
! 	if (fcache->readonly_func)
! 		snapshot = GetActiveSnapshot();
! 	else
! 	{
! 		CommandCounterIncrement();
! 		snapshot = GetTransactionSnapshot();
! 	}
  
  	/*
  	 * If this query produces the function result, send its output to the
--- 391,401 ----
  static void
  postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  {
  	DestReceiver *dest;
  
  	Assert(es->qd == NULL);
  
! 	Assert(ActiveSnapshotSet());
  
  	/*
  	 * If this query produces the function result, send its output to the
***************
*** 415,427 **** postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  	if (IsA(es->stmt, PlannedStmt))
  		es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
  								 fcache->src,
! 								 snapshot, InvalidSnapshot,
  								 dest,
  								 fcache->paramLI, 0);
  	else
  		es->qd = CreateUtilityQueryDesc(es->stmt,
  										fcache->src,
! 										snapshot,
  										dest,
  										fcache->paramLI);
  
--- 419,432 ----
  	if (IsA(es->stmt, PlannedStmt))
  		es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
  								 fcache->src,
! 								 GetActiveSnapshot(),
! 								 InvalidSnapshot,
  								 dest,
  								 fcache->paramLI, 0);
  	else
  		es->qd = CreateUtilityQueryDesc(es->stmt,
  										fcache->src,
! 										GetActiveSnapshot(),
  										dest,
  										fcache->paramLI);
  
***************
*** 617,622 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 622,629 ----
  	execution_state *es;
  	TupleTableSlot *slot;
  	Datum		result;
+ 	List		*eslist;
+ 	ListCell    *eslc;
  
  	/*
  	 * Switch to context in which the fcache lives.  This ensures that
***************
*** 668,680 **** fmgr_sql(PG_FUNCTION_ARGS)
  		init_sql_fcache(fcinfo->flinfo, lazyEvalOK);
  		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
  	}
! 	es = fcache->func_state;
  
  	/*
  	 * Convert params to appropriate format if starting a fresh execution. (If
  	 * continuing execution, we can re-use prior params.)
  	 */
! 	if (es && es->status == F_EXEC_START)
  		postquel_sub_params(fcache, fcinfo);
  
  	/*
--- 675,687 ----
  		init_sql_fcache(fcinfo->flinfo, lazyEvalOK);
  		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
  	}
! 	eslist = fcache->func_state;
  
  	/*
  	 * Convert params to appropriate format if starting a fresh execution. (If
  	 * continuing execution, we can re-use prior params.)
  	 */
! 	if (linitial(eslist) && ((execution_state *) linitial(eslist))->status == F_EXEC_START)
  		postquel_sub_params(fcache, fcinfo);
  
  	/*
***************
*** 687,694 **** fmgr_sql(PG_FUNCTION_ARGS)
  	/*
  	 * Find first unfinished query in function.
  	 */
! 	while (es && es->status == F_EXEC_DONE)
! 		es = es->next;
  
  	/*
  	 * Execute each command in the function one after another until we either
--- 694,709 ----
  	/*
  	 * Find first unfinished query in function.
  	 */
! 	foreach(eslc, eslist)
! 	{
! 		es = (execution_state *) lfirst(eslc);
! 
! 		while (es && es->status == F_EXEC_DONE)
! 			es = es->next;
! 
! 		if (es)
! 			break;
! 	}
  
  	/*
  	 * Execute each command in the function one after another until we either
***************
*** 699,706 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 714,744 ----
  		bool		completed;
  
  		if (es->status == F_EXEC_START)
+ 		{
+ 			if (!fcache->readonly_func)
+ 			{
+ 				/*
+ 				 * In a read-only function, use the surrounding query's snapshot;
+ 				 * otherwise take a new snapshot if we don't have one yet.  The
+ 				 * snapshot should include a fresh command ID so that all work to
+ 				 * date in this transaction is visible.
+ 				 */
+ 				if (!fcache->snapshot)
+ 				{
+ 					CommandCounterIncrement();
+ 					fcache->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+ 					PushActiveSnapshot(fcache->snapshot);
+ 				}
+ 				else
+ 					PushUpdatedSnapshot(fcache->snapshot);
+ 			}
+ 			
  			postquel_start(es, fcache);
  
+ 			if (!fcache->readonly_func)
+ 				PopActiveSnapshot();
+ 		}
+ 
  		completed = postquel_getnext(es, fcache);
  
  		/*
***************
*** 726,731 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 764,783 ----
  		if (es->status != F_EXEC_DONE)
  			break;
  		es = es->next;
+ 
+ 		if (!es)
+ 		{
+ 			eslc = lnext(eslc);
+ 			if (!eslc)
+ 				break;
+ 
+ 			es = (execution_state *) lfirst(eslc);
+ 
+ 			/* make sure we take a new snapshot for this query list */
+ 			Assert(fcache->snapshot != InvalidSnapshot);
+ 			UnregisterSnapshot(fcache->snapshot);
+ 			fcache->snapshot = InvalidSnapshot;
+ 		}
  	}
  
  	/*
***************
*** 794,799 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 846,856 ----
  											  PointerGetDatum(fcache));
  				fcache->shutdown_reg = false;
  			}
+ 
+ 			/* Unregister snapshot if we have one */
+ 			if (fcache->snapshot != InvalidSnapshot)
+ 				UnregisterSnapshot(fcache->snapshot);
+ 			fcache->snapshot = InvalidSnapshot;
  		}
  		else
  		{
***************
*** 820,825 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 877,887 ----
  											  PointerGetDatum(fcache));
  				fcache->shutdown_reg = false;
  			}
+ 
+ 			/* Unregister snapshot if we have one */
+ 			if (fcache->snapshot != InvalidSnapshot)
+ 				UnregisterSnapshot(fcache->snapshot);
+ 			fcache->snapshot = InvalidSnapshot;
  		}
  	}
  	else
***************
*** 850,855 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 912,922 ----
  
  		/* Clear the tuplestore, but keep it for next time */
  		tuplestore_clear(fcache->tstore);
+ 
+ 		/* Unregister snapshot if we have one */
+ 		if (fcache->snapshot != InvalidSnapshot)
+ 			UnregisterSnapshot(fcache->snapshot);
+ 		fcache->snapshot = InvalidSnapshot;
  	}
  
  	/*
***************
*** 858,868 **** fmgr_sql(PG_FUNCTION_ARGS)
  	 */
  	if (es == NULL)
  	{
! 		es = fcache->func_state;
! 		while (es)
  		{
! 			es->status = F_EXEC_START;
! 			es = es->next;
  		}
  	}
  
--- 925,938 ----
  	 */
  	if (es == NULL)
  	{
! 		foreach(eslc, fcache->func_state)
  		{
! 			es = (execution_state *) lfirst(eslc);
! 			while (es)
! 			{
! 				es->status = F_EXEC_START;
! 				es = es->next;
! 			}
  		}
  	}
  
***************
*** 913,931 **** sql_exec_error_callback(void *arg)
  	{
  		execution_state *es;
  		int			query_num;
  
- 		es = fcache->func_state;
  		query_num = 1;
! 		while (es)
  		{
! 			if (es->qd)
  			{
! 				errcontext("SQL function \"%s\" statement %d",
! 						   fcache->fname, query_num);
! 				break;
  			}
- 			es = es->next;
- 			query_num++;
  		}
  		if (es == NULL)
  		{
--- 983,1006 ----
  	{
  		execution_state *es;
  		int			query_num;
+ 		ListCell   *lc;
  
  		query_num = 1;
! 
! 		foreach(lc, fcache->func_state)
  		{
! 			es = (execution_state *) lfirst(lc);
! 			while (es)
  			{
! 				if (es->qd)
! 				{
! 					errcontext("SQL function \"%s\" statement %d",
! 							   fcache->fname, query_num);
! 					break;
! 				}
! 				es = es->next;
! 				query_num++;
  			}
  		}
  		if (es == NULL)
  		{
***************
*** 956,973 **** static void
  ShutdownSQLFunction(Datum arg)
  {
  	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
! 	execution_state *es = fcache->func_state;
  
! 	while (es != NULL)
  	{
! 		/* Shut down anything still running */
! 		if (es->status == F_EXEC_RUN)
! 			postquel_end(es);
! 		/* Reset states to START in case we're called again */
! 		es->status = F_EXEC_START;
! 		es = es->next;
  	}
  
  	/* Release tuplestore if we have one */
  	if (fcache->tstore)
  		tuplestore_end(fcache->tstore);
--- 1031,1059 ----
  ShutdownSQLFunction(Datum arg)
  {
  	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
! 	execution_state *es;
! 	ListCell		*lc;
  
! 	foreach(lc, fcache->func_state)
  	{
! 		es = (execution_state *) lfirst(lc);
! 
! 		while (es)
! 		{
! 			/* Shut down anything still running */
! 			if (es->status == F_EXEC_RUN)
! 				postquel_end(es);
! 			/* Reset states to START in case we're called again */
! 			es->status = F_EXEC_START;
! 			es = es->next;
! 		}
  	}
  
+ 	/* Unregister snapshot if we have one */
+ 	if (fcache->snapshot != InvalidSnapshot)
+ 		UnregisterSnapshot(fcache->snapshot);
+ 	fcache->snapshot = InvalidSnapshot;
+ 
  	/* Release tuplestore if we have one */
  	if (fcache->tstore)
  		tuplestore_end(fcache->tstore);
*** a/src/backend/executor/spi.c
--- b/src/backend/executor/spi.c
***************
*** 1769,1774 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
--- 1769,1775 ----
  	SPITupleTable *my_tuptable = NULL;
  	int			res = 0;
  	bool		have_active_snap = ActiveSnapshotSet();
+ 	bool		registered_snap = false;
  	ErrorContextCallback spierrcontext;
  	CachedPlan *cplan = NULL;
  	ListCell   *lc1;
***************
*** 1872,1879 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
  				}
  				else
  				{
! 					PushActiveSnapshot(GetTransactionSnapshot());
  					pushed_active_snap = true;
  				}
  			}
  			else
--- 1873,1882 ----
  				}
  				else
  				{
! 					snapshot = RegisterSnapshot(GetTransactionSnapshot());
! 					PushActiveSnapshot(snapshot);
  					pushed_active_snap = true;
+ 					registered_snap = true;
  				}
  			}
  			else
***************
*** 1966,1975 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
--- 1969,1991 ----
  		 */
  		if (!read_only)
  			CommandCounterIncrement();
+ 
+ 		/*
+ 		 * If we took a new snapshot for this query list, unregister it and
+ 		 * make sure we take a new one for the next list.
+ 		 */
+ 		if (registered_snap)
+ 		{
+ 			UnregisterSnapshot(snapshot);
+ 			snapshot = InvalidSnapshot;
+ 		}
  	}
  
  fail:
  
+ 	if (registered_snap)
+ 		UnregisterSnapshot(snapshot);
+ 
  	/* We no longer need the cached plan refcount, if any */
  	if (cplan)
  		ReleaseCachedPlan(cplan, true);
*** a/src/backend/tcop/postgres.c
--- b/src/backend/tcop/postgres.c
***************
*** 537,547 **** pg_parse_and_rewrite(const char *query_string,	/* string to execute */
  	{
  		Node	   *parsetree = (Node *) lfirst(list_item);
  
! 		querytree_list = list_concat(querytree_list,
! 									 pg_analyze_and_rewrite(parsetree,
! 															query_string,
! 															paramTypes,
! 															numParams));
  	}
  
  	return querytree_list;
--- 537,547 ----
  	{
  		Node	   *parsetree = (Node *) lfirst(list_item);
  
! 		querytree_list = lappend(querytree_list,
! 								 pg_analyze_and_rewrite(parsetree,
! 														query_string,
! 														paramTypes,
! 														numParams));
  	}
  
  	return querytree_list;
*** a/src/backend/tcop/pquery.c
--- b/src/backend/tcop/pquery.c
***************
*** 170,180 **** ProcessQuery(PlannedStmt *plan,
  	elog(DEBUG3, "ProcessQuery");
  
  	/*
- 	 * Must always set a snapshot for plannable queries.
- 	 */
- 	PushActiveSnapshot(GetTransactionSnapshot());
- 
- 	/*
  	 * Create the QueryDesc object
  	 */
  	queryDesc = CreateQueryDesc(plan, sourceText,
--- 170,175 ----
***************
*** 234,241 **** ProcessQuery(PlannedStmt *plan,
  	/* Now take care of any queued AFTER triggers */
  	AfterTriggerEndQuery(queryDesc->estate);
  
- 	PopActiveSnapshot();
- 
  	/*
  	 * Now, we close down all the scans and free allocated resources.
  	 */
--- 229,234 ----
***************
*** 1220,1225 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1213,1219 ----
  			   char *completionTag)
  {
  	ListCell   *stmtlist_item;
+ 	Snapshot	snapshot = InvalidSnapshot;
  
  	/*
  	 * If the destination is DestRemoteExecute, change to DestNone.  The
***************
*** 1262,1267 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1256,1270 ----
  			if (log_executor_stats)
  				ResetUsage();
  
+ 			/* if no snapshot is set, grab a new one and register it */
+ 			if (snapshot == InvalidSnapshot)
+ 			{
+ 				snapshot = RegisterSnapshot(GetTransactionSnapshot());
+ 				PushActiveSnapshot(snapshot);
+ 			}
+ 			else
+ 				PushUpdatedSnapshot(snapshot);
+ 
  			if (pstmt->canSetTag)
  			{
  				/* statement can set tag string */
***************
*** 1279,1284 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1282,1289 ----
  							 altdest, NULL);
  			}
  
+ 			PopActiveSnapshot();
+ 
  			if (log_executor_stats)
  				ShowUsage("EXECUTOR STATISTICS");
  
***************
*** 1291,1301 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1296,1320 ----
  			 *
  			 * These are assumed canSetTag if they're the only stmt in the
  			 * portal.
+ 			 *
+ 			 * NotifyStmt is the only utility statement allowed in a list of
+ 			 * rewritten queries, and it doesn't need a snapshot so we don't
+ 			 * need to worry about it.  However, if the list has only one
+ 			 * statement and it's a utility statement, we are not allowed to
+ 			 * take a snapshot.  See the first comment in PortalRunUtility().
  			 */
  			if (list_length(portal->stmts) == 1)
+ 			{
+ 				Assert(snapshot == InvalidSnapshot);
+ 
  				PortalRunUtility(portal, stmt, isTopLevel, dest, completionTag);
+ 			}
  			else
+ 			{
+ 				Assert(IsA(stmt, NotifyStmt));
+ 
  				PortalRunUtility(portal, stmt, isTopLevel, altdest, NULL);
+ 			}
  		}
  
  		/*
***************
*** 1313,1318 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1332,1340 ----
  		MemoryContextDeleteChildren(PortalGetHeapMemory(portal));
  	}
  
+ 	if (snapshot != InvalidSnapshot)
+ 		UnregisterSnapshot(snapshot);
+ 
  	/*
  	 * If a command completion tag was supplied, use it.  Otherwise use the
  	 * portal's commandTag as the default completion tag.

*** a/src/backend/catalog/pg_proc.c
--- b/src/backend/catalog/pg_proc.c
***************
*** 832,838 **** fmgr_sql_validator(PG_FUNCTION_ARGS)
  												  proc->proargtypes.values,
  												  proc->pronargs);
  			(void) check_sql_fn_retval(funcoid, proc->prorettype,
! 									   querytree_list,
  									   NULL, NULL);
  		}
  		else
--- 832,838 ----
  												  proc->proargtypes.values,
  												  proc->pronargs);
  			(void) check_sql_fn_retval(funcoid, proc->prorettype,
! 									   llast(querytree_list),
  									   NULL, NULL);
  		}
  		else
*** a/src/backend/executor/functions.c
--- b/src/backend/executor/functions.c
***************
*** 90,107 **** typedef struct
  	ParamListInfo paramLI;		/* Param list representing current args */
  
  	Tuplestorestate *tstore;	/* where we accumulate result tuples */
  
  	JunkFilter *junkFilter;		/* will be NULL if function returns VOID */
  
! 	/* head of linked list of execution_state records */
! 	execution_state *func_state;
  } SQLFunctionCache;
  
  typedef SQLFunctionCache *SQLFunctionCachePtr;
  
  
  /* non-export function prototypes */
! static execution_state *init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK);
  static void init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK);
--- 90,107 ----
  	ParamListInfo paramLI;		/* Param list representing current args */
  
  	Tuplestorestate *tstore;	/* where we accumulate result tuples */
+ 	Snapshot	snapshot;
  
  	JunkFilter *junkFilter;		/* will be NULL if function returns VOID */
  
! 	List *func_state;
  } SQLFunctionCache;
  
  typedef SQLFunctionCache *SQLFunctionCachePtr;
  
  
  /* non-export function prototypes */
! static List *init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK);
  static void init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK);
***************
*** 123,183 **** static void sqlfunction_destroy(DestReceiver *self);
  
  
  /* Set up the list of per-query execution_state records for a SQL function */
! static execution_state *
  init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK)
  {
! 	execution_state *firstes = NULL;
! 	execution_state *preves = NULL;
  	execution_state *lasttages = NULL;
! 	ListCell   *qtl_item;
  
! 	foreach(qtl_item, queryTree_list)
  	{
! 		Query	   *queryTree = (Query *) lfirst(qtl_item);
! 		Node	   *stmt;
! 		execution_state *newes;
  
! 		Assert(IsA(queryTree, Query));
  
! 		if (queryTree->commandType == CMD_UTILITY)
! 			stmt = queryTree->utilityStmt;
! 		else
! 			stmt = (Node *) pg_plan_query(queryTree, 0, NULL);
  
! 		/* Precheck all commands for validity in a function */
! 		if (IsA(stmt, TransactionStmt))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 			/* translator: %s is a SQL statement name */
! 					 errmsg("%s is not allowed in a SQL function",
! 							CreateCommandTag(stmt))));
  
! 		if (fcache->readonly_func && !CommandIsReadOnly(stmt))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 			/* translator: %s is a SQL statement name */
! 					 errmsg("%s is not allowed in a non-volatile function",
! 							CreateCommandTag(stmt))));
  
! 		newes = (execution_state *) palloc(sizeof(execution_state));
! 		if (preves)
! 			preves->next = newes;
! 		else
! 			firstes = newes;
  
! 		newes->next = NULL;
! 		newes->status = F_EXEC_START;
! 		newes->setsResult = false;		/* might change below */
! 		newes->lazyEval = false;	/* might change below */
! 		newes->stmt = stmt;
! 		newes->qd = NULL;
  
! 		if (queryTree->canSetTag)
! 			lasttages = newes;
  
! 		preves = newes;
  	}
  
  	/*
--- 123,200 ----
  
  
  /* Set up the list of per-query execution_state records for a SQL function */
! static List *
  init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK)
  {
! 	execution_state *firstes;
! 	execution_state *preves;
  	execution_state *lasttages = NULL;
! 	List	   *eslist;
! 	ListCell   *lc1;
! 	ListCell   *lc2;
! 	List	   *qtlist;
! 	Query	   *queryTree;
! 
! 
! 	eslist = NIL;
  
! 	foreach(lc1, queryTree_list)
  	{
! 		qtlist = (List *) lfirst(lc1);
! 		firstes = NULL;
! 		preves = NULL;
  
! 		foreach(lc2, qtlist)
! 		{
! 			Node	   *stmt;
! 			execution_state *newes;
  
! 			queryTree = (Query *) lfirst(lc2);
  
! 			Assert(IsA(queryTree, Query));
  
! 			if (queryTree->commandType == CMD_UTILITY)
! 				stmt = queryTree->utilityStmt;
! 			else
! 				stmt = (Node *) pg_plan_query(queryTree, 0, NULL);
  
! 			/* Precheck all commands for validity in a function */
! 			if (IsA(stmt, TransactionStmt))
! 				ereport(ERROR,
! 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 				/* translator: %s is a SQL statement name */
! 						 errmsg("%s is not allowed in a SQL function",
! 								CreateCommandTag(stmt))));
  
! 			if (fcache->readonly_func && !CommandIsReadOnly(stmt))
! 				ereport(ERROR,
! 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 				/* translator: %s is a SQL statement name */
! 						 errmsg("%s is not allowed in a non-volatile function",
! 								CreateCommandTag(stmt))));
! 
! 			newes = (execution_state *) palloc(sizeof(execution_state));
! 			if (preves)
! 				preves->next = newes;
! 			else
! 				firstes = newes;
  
! 			newes->next = NULL;
! 			newes->status = F_EXEC_START;
! 			newes->setsResult = false;		/* might change below */
! 			newes->lazyEval = false;	/* might change below */
! 			newes->stmt = stmt;
! 			newes->qd = NULL;
  
! 			if (queryTree->canSetTag)
! 				lasttages = newes;
! 
! 			preves = newes;
! 		}
! 
! 		eslist = lappend(eslist, firstes);
  	}
  
  	/*
***************
*** 210,216 **** init_execution_state(List *queryTree_list,
  		}
  	}
  
! 	return firstes;
  }
  
  /* Initialize the SQLFunctionCache for a SQL function */
--- 227,233 ----
  		}
  	}
  
! 	return eslist;
  }
  
  /* Initialize the SQLFunctionCache for a SQL function */
***************
*** 342,348 **** init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK)
  	 */
  	fcache->returnsTuple = check_sql_fn_retval(foid,
  											   rettype,
! 											   queryTree_list,
  											   NULL,
  											   &fcache->junkFilter);
  
--- 359,365 ----
  	 */
  	fcache->returnsTuple = check_sql_fn_retval(foid,
  											   rettype,
! 											   llast(queryTree_list),
  											   NULL,
  											   &fcache->junkFilter);
  
***************
*** 374,397 **** init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK)
  static void
  postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  {
- 	Snapshot	snapshot;
  	DestReceiver *dest;
  
  	Assert(es->qd == NULL);
  
! 	/*
! 	 * In a read-only function, use the surrounding query's snapshot;
! 	 * otherwise take a new snapshot for each query.  The snapshot should
! 	 * include a fresh command ID so that all work to date in this transaction
! 	 * is visible.
! 	 */
! 	if (fcache->readonly_func)
! 		snapshot = GetActiveSnapshot();
! 	else
! 	{
! 		CommandCounterIncrement();
! 		snapshot = GetTransactionSnapshot();
! 	}
  
  	/*
  	 * If this query produces the function result, send its output to the
--- 391,401 ----
  static void
  postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  {
  	DestReceiver *dest;
  
  	Assert(es->qd == NULL);
  
! 	Assert(ActiveSnapshotSet());
  
  	/*
  	 * If this query produces the function result, send its output to the
***************
*** 415,427 **** postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  	if (IsA(es->stmt, PlannedStmt))
  		es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
  								 fcache->src,
! 								 snapshot, InvalidSnapshot,
  								 dest,
  								 fcache->paramLI, 0);
  	else
  		es->qd = CreateUtilityQueryDesc(es->stmt,
  										fcache->src,
! 										snapshot,
  										dest,
  										fcache->paramLI);
  
--- 419,432 ----
  	if (IsA(es->stmt, PlannedStmt))
  		es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
  								 fcache->src,
! 								 GetActiveSnapshot(),
! 								 InvalidSnapshot,
  								 dest,
  								 fcache->paramLI, 0);
  	else
  		es->qd = CreateUtilityQueryDesc(es->stmt,
  										fcache->src,
! 										GetActiveSnapshot(),
  										dest,
  										fcache->paramLI);
  
***************
*** 617,622 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 622,629 ----
  	execution_state *es;
  	TupleTableSlot *slot;
  	Datum		result;
+ 	List		*eslist;
+ 	ListCell    *eslc;
  
  	/*
  	 * Switch to context in which the fcache lives.  This ensures that
***************
*** 668,680 **** fmgr_sql(PG_FUNCTION_ARGS)
  		init_sql_fcache(fcinfo->flinfo, lazyEvalOK);
  		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
  	}
! 	es = fcache->func_state;
  
  	/*
  	 * Convert params to appropriate format if starting a fresh execution. (If
  	 * continuing execution, we can re-use prior params.)
  	 */
! 	if (es && es->status == F_EXEC_START)
  		postquel_sub_params(fcache, fcinfo);
  
  	/*
--- 675,687 ----
  		init_sql_fcache(fcinfo->flinfo, lazyEvalOK);
  		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
  	}
! 	eslist = fcache->func_state;
  
  	/*
  	 * Convert params to appropriate format if starting a fresh execution. (If
  	 * continuing execution, we can re-use prior params.)
  	 */
! 	if (linitial(eslist) && ((execution_state *) linitial(eslist))->status == F_EXEC_START)
  		postquel_sub_params(fcache, fcinfo);
  
  	/*
***************
*** 687,694 **** fmgr_sql(PG_FUNCTION_ARGS)
  	/*
  	 * Find first unfinished query in function.
  	 */
! 	while (es && es->status == F_EXEC_DONE)
! 		es = es->next;
  
  	/*
  	 * Execute each command in the function one after another until we either
--- 694,709 ----
  	/*
  	 * Find first unfinished query in function.
  	 */
! 	foreach(eslc, eslist)
! 	{
! 		es = (execution_state *) lfirst(eslc);
! 
! 		while (es && es->status == F_EXEC_DONE)
! 			es = es->next;
! 
! 		if (es)
! 			break;
! 	}
  
  	/*
  	 * Execute each command in the function one after another until we either
***************
*** 699,706 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 714,744 ----
  		bool		completed;
  
  		if (es->status == F_EXEC_START)
+ 		{
+ 			if (!fcache->readonly_func)
+ 			{
+ 				/*
+ 				 * In a read-only function, use the surrounding query's snapshot;
+ 				 * otherwise take a new snapshot if we don't have one yet.  The
+ 				 * snapshot should include a fresh command ID so that all work to
+ 				 * date in this transaction is visible.
+ 				 */
+ 				if (!fcache->snapshot)
+ 				{
+ 					CommandCounterIncrement();
+ 					fcache->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+ 					PushActiveSnapshot(fcache->snapshot);
+ 				}
+ 				else
+ 					PushUpdatedSnapshot(fcache->snapshot);
+ 			}
+ 			
  			postquel_start(es, fcache);
  
+ 			if (!fcache->readonly_func)
+ 				PopActiveSnapshot();
+ 		}
+ 
  		completed = postquel_getnext(es, fcache);
  
  		/*
***************
*** 726,731 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 764,788 ----
  		if (es->status != F_EXEC_DONE)
  			break;
  		es = es->next;
+ 
+ 		if (!es)
+ 		{
+ 			eslc = lnext(eslc);
+ 			if (!eslc)
+ 				break;
+ 
+ 			es = (execution_state *) lfirst(eslc);
+ 
+ 			/* make sure we take a new snapshot for this query list */
+ 			if (!fcache->readonly_func)
+ 			{
+ 				Assert(fcache->snapshot != InvalidSnapshot);
+ 				UnregisterSnapshot(fcache->snapshot);
+ 				fcache->snapshot = InvalidSnapshot;
+ 			}
+ 			else
+ 				Assert(fcache->snapshot == InvalidSnapshot);
+ 		}
  	}
  
  	/*
***************
*** 794,799 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 851,861 ----
  											  PointerGetDatum(fcache));
  				fcache->shutdown_reg = false;
  			}
+ 
+ 			/* Unregister snapshot if we have one */
+ 			if (fcache->snapshot != InvalidSnapshot)
+ 				UnregisterSnapshot(fcache->snapshot);
+ 			fcache->snapshot = InvalidSnapshot;
  		}
  		else
  		{
***************
*** 820,825 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 882,892 ----
  											  PointerGetDatum(fcache));
  				fcache->shutdown_reg = false;
  			}
+ 
+ 			/* Unregister snapshot if we have one */
+ 			if (fcache->snapshot != InvalidSnapshot)
+ 				UnregisterSnapshot(fcache->snapshot);
+ 			fcache->snapshot = InvalidSnapshot;
  		}
  	}
  	else
***************
*** 850,855 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 917,927 ----
  
  		/* Clear the tuplestore, but keep it for next time */
  		tuplestore_clear(fcache->tstore);
+ 
+ 		/* Unregister snapshot if we have one */
+ 		if (fcache->snapshot != InvalidSnapshot)
+ 			UnregisterSnapshot(fcache->snapshot);
+ 		fcache->snapshot = InvalidSnapshot;
  	}
  
  	/*
***************
*** 858,868 **** fmgr_sql(PG_FUNCTION_ARGS)
  	 */
  	if (es == NULL)
  	{
! 		es = fcache->func_state;
! 		while (es)
  		{
! 			es->status = F_EXEC_START;
! 			es = es->next;
  		}
  	}
  
--- 930,943 ----
  	 */
  	if (es == NULL)
  	{
! 		foreach(eslc, fcache->func_state)
  		{
! 			es = (execution_state *) lfirst(eslc);
! 			while (es)
! 			{
! 				es->status = F_EXEC_START;
! 				es = es->next;
! 			}
  		}
  	}
  
***************
*** 913,931 **** sql_exec_error_callback(void *arg)
  	{
  		execution_state *es;
  		int			query_num;
  
- 		es = fcache->func_state;
  		query_num = 1;
! 		while (es)
  		{
! 			if (es->qd)
  			{
! 				errcontext("SQL function \"%s\" statement %d",
! 						   fcache->fname, query_num);
! 				break;
  			}
- 			es = es->next;
- 			query_num++;
  		}
  		if (es == NULL)
  		{
--- 988,1011 ----
  	{
  		execution_state *es;
  		int			query_num;
+ 		ListCell   *lc;
  
  		query_num = 1;
! 
! 		foreach(lc, fcache->func_state)
  		{
! 			es = (execution_state *) lfirst(lc);
! 			while (es)
  			{
! 				if (es->qd)
! 				{
! 					errcontext("SQL function \"%s\" statement %d",
! 							   fcache->fname, query_num);
! 					break;
! 				}
! 				es = es->next;
! 				query_num++;
  			}
  		}
  		if (es == NULL)
  		{
***************
*** 956,973 **** static void
  ShutdownSQLFunction(Datum arg)
  {
  	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
! 	execution_state *es = fcache->func_state;
  
! 	while (es != NULL)
  	{
! 		/* Shut down anything still running */
! 		if (es->status == F_EXEC_RUN)
! 			postquel_end(es);
! 		/* Reset states to START in case we're called again */
! 		es->status = F_EXEC_START;
! 		es = es->next;
  	}
  
  	/* Release tuplestore if we have one */
  	if (fcache->tstore)
  		tuplestore_end(fcache->tstore);
--- 1036,1064 ----
  ShutdownSQLFunction(Datum arg)
  {
  	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
! 	execution_state *es;
! 	ListCell		*lc;
  
! 	foreach(lc, fcache->func_state)
  	{
! 		es = (execution_state *) lfirst(lc);
! 
! 		while (es)
! 		{
! 			/* Shut down anything still running */
! 			if (es->status == F_EXEC_RUN)
! 				postquel_end(es);
! 			/* Reset states to START in case we're called again */
! 			es->status = F_EXEC_START;
! 			es = es->next;
! 		}
  	}
  
+ 	/* Unregister snapshot if we have one */
+ 	if (fcache->snapshot != InvalidSnapshot)
+ 		UnregisterSnapshot(fcache->snapshot);
+ 	fcache->snapshot = InvalidSnapshot;
+ 
  	/* Release tuplestore if we have one */
  	if (fcache->tstore)
  		tuplestore_end(fcache->tstore);
*** a/src/backend/executor/spi.c
--- b/src/backend/executor/spi.c
***************
*** 1769,1774 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
--- 1769,1775 ----
  	SPITupleTable *my_tuptable = NULL;
  	int			res = 0;
  	bool		have_active_snap = ActiveSnapshotSet();
+ 	bool		registered_snap = false;
  	ErrorContextCallback spierrcontext;
  	CachedPlan *cplan = NULL;
  	ListCell   *lc1;
***************
*** 1872,1879 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
  				}
  				else
  				{
! 					PushActiveSnapshot(GetTransactionSnapshot());
  					pushed_active_snap = true;
  				}
  			}
  			else
--- 1873,1882 ----
  				}
  				else
  				{
! 					snapshot = RegisterSnapshot(GetTransactionSnapshot());
! 					PushActiveSnapshot(snapshot);
  					pushed_active_snap = true;
+ 					registered_snap = true;
  				}
  			}
  			else
***************
*** 1966,1975 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
--- 1969,1991 ----
  		 */
  		if (!read_only)
  			CommandCounterIncrement();
+ 
+ 		/*
+ 		 * If we took a new snapshot for this query list, unregister it and
+ 		 * make sure we take a new one for the next list.
+ 		 */
+ 		if (registered_snap)
+ 		{
+ 			UnregisterSnapshot(snapshot);
+ 			snapshot = InvalidSnapshot;
+ 		}
  	}
  
  fail:
  
+ 	if (registered_snap)
+ 		UnregisterSnapshot(snapshot);
+ 
  	/* We no longer need the cached plan refcount, if any */
  	if (cplan)
  		ReleaseCachedPlan(cplan, true);
*** a/src/backend/tcop/postgres.c
--- b/src/backend/tcop/postgres.c
***************
*** 537,547 **** pg_parse_and_rewrite(const char *query_string,	/* string to execute */
  	{
  		Node	   *parsetree = (Node *) lfirst(list_item);
  
! 		querytree_list = list_concat(querytree_list,
! 									 pg_analyze_and_rewrite(parsetree,
! 															query_string,
! 															paramTypes,
! 															numParams));
  	}
  
  	return querytree_list;
--- 537,547 ----
  	{
  		Node	   *parsetree = (Node *) lfirst(list_item);
  
! 		querytree_list = lappend(querytree_list,
! 								 pg_analyze_and_rewrite(parsetree,
! 														query_string,
! 														paramTypes,
! 														numParams));
  	}
  
  	return querytree_list;
*** a/src/backend/tcop/pquery.c
--- b/src/backend/tcop/pquery.c
***************
*** 170,180 **** ProcessQuery(PlannedStmt *plan,
  	elog(DEBUG3, "ProcessQuery");
  
  	/*
- 	 * Must always set a snapshot for plannable queries.
- 	 */
- 	PushActiveSnapshot(GetTransactionSnapshot());
- 
- 	/*
  	 * Create the QueryDesc object
  	 */
  	queryDesc = CreateQueryDesc(plan, sourceText,
--- 170,175 ----
***************
*** 234,241 **** ProcessQuery(PlannedStmt *plan,
  	/* Now take care of any queued AFTER triggers */
  	AfterTriggerEndQuery(queryDesc->estate);
  
- 	PopActiveSnapshot();
- 
  	/*
  	 * Now, we close down all the scans and free allocated resources.
  	 */
--- 229,234 ----
***************
*** 1220,1225 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1213,1219 ----
  			   char *completionTag)
  {
  	ListCell   *stmtlist_item;
+ 	Snapshot	snapshot = InvalidSnapshot;
  
  	/*
  	 * If the destination is DestRemoteExecute, change to DestNone.  The
***************
*** 1262,1267 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1256,1270 ----
  			if (log_executor_stats)
  				ResetUsage();
  
+ 			/* if no snapshot is set, grab a new one and register it */
+ 			if (snapshot == InvalidSnapshot)
+ 			{
+ 				snapshot = RegisterSnapshot(GetTransactionSnapshot());
+ 				PushActiveSnapshot(snapshot);
+ 			}
+ 			else
+ 				PushUpdatedSnapshot(snapshot);
+ 
  			if (pstmt->canSetTag)
  			{
  				/* statement can set tag string */
***************
*** 1279,1284 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1282,1289 ----
  							 altdest, NULL);
  			}
  
+ 			PopActiveSnapshot();
+ 
  			if (log_executor_stats)
  				ShowUsage("EXECUTOR STATISTICS");
  
***************
*** 1291,1301 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1296,1320 ----
  			 *
  			 * These are assumed canSetTag if they're the only stmt in the
  			 * portal.
+ 			 *
+ 			 * NotifyStmt is the only utility statement allowed in a list of
+ 			 * rewritten queries, and it doesn't need a snapshot so we don't
+ 			 * need to worry about it.  However, if the list has only one
+ 			 * statement and it's a utility statement, we are not allowed to
+ 			 * take a snapshot.  See the first comment in PortalRunUtility().
  			 */
  			if (list_length(portal->stmts) == 1)
+ 			{
+ 				Assert(snapshot == InvalidSnapshot);
+ 
  				PortalRunUtility(portal, stmt, isTopLevel, dest, completionTag);
+ 			}
  			else
+ 			{
+ 				Assert(IsA(stmt, NotifyStmt));
+ 
  				PortalRunUtility(portal, stmt, isTopLevel, altdest, NULL);
+ 			}
  		}
  
  		/*
***************
*** 1313,1318 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1332,1340 ----
  		MemoryContextDeleteChildren(PortalGetHeapMemory(portal));
  	}
  
+ 	if (snapshot != InvalidSnapshot)
+ 		UnregisterSnapshot(snapshot);
+ 
  	/*
  	 * If a command completion tag was supplied, use it.  Otherwise use the
  	 * portal's commandTag as the default completion tag.

*** a/src/backend/catalog/pg_proc.c
--- b/src/backend/catalog/pg_proc.c
***************
*** 832,838 **** fmgr_sql_validator(PG_FUNCTION_ARGS)
  												  proc->proargtypes.values,
  												  proc->pronargs);
  			(void) check_sql_fn_retval(funcoid, proc->prorettype,
! 									   querytree_list,
  									   NULL, NULL);
  		}
  		else
--- 832,838 ----
  												  proc->proargtypes.values,
  												  proc->pronargs);
  			(void) check_sql_fn_retval(funcoid, proc->prorettype,
! 									   llast(querytree_list),
  									   NULL, NULL);
  		}
  		else
*** a/src/backend/executor/functions.c
--- b/src/backend/executor/functions.c
***************
*** 90,107 **** typedef struct
  	ParamListInfo paramLI;		/* Param list representing current args */
  
  	Tuplestorestate *tstore;	/* where we accumulate result tuples */
  
  	JunkFilter *junkFilter;		/* will be NULL if function returns VOID */
  
! 	/* head of linked list of execution_state records */
! 	execution_state *func_state;
  } SQLFunctionCache;
  
  typedef SQLFunctionCache *SQLFunctionCachePtr;
  
  
  /* non-export function prototypes */
! static execution_state *init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK);
  static void init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK);
--- 90,107 ----
  	ParamListInfo paramLI;		/* Param list representing current args */
  
  	Tuplestorestate *tstore;	/* where we accumulate result tuples */
+ 	Snapshot	snapshot;
  
  	JunkFilter *junkFilter;		/* will be NULL if function returns VOID */
  
! 	List *func_state;
  } SQLFunctionCache;
  
  typedef SQLFunctionCache *SQLFunctionCachePtr;
  
  
  /* non-export function prototypes */
! static List *init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK);
  static void init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK);
***************
*** 123,183 **** static void sqlfunction_destroy(DestReceiver *self);
  
  
  /* Set up the list of per-query execution_state records for a SQL function */
! static execution_state *
  init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK)
  {
! 	execution_state *firstes = NULL;
! 	execution_state *preves = NULL;
  	execution_state *lasttages = NULL;
! 	ListCell   *qtl_item;
  
! 	foreach(qtl_item, queryTree_list)
  	{
! 		Query	   *queryTree = (Query *) lfirst(qtl_item);
! 		Node	   *stmt;
! 		execution_state *newes;
  
! 		Assert(IsA(queryTree, Query));
  
! 		if (queryTree->commandType == CMD_UTILITY)
! 			stmt = queryTree->utilityStmt;
! 		else
! 			stmt = (Node *) pg_plan_query(queryTree, 0, NULL);
  
! 		/* Precheck all commands for validity in a function */
! 		if (IsA(stmt, TransactionStmt))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 			/* translator: %s is a SQL statement name */
! 					 errmsg("%s is not allowed in a SQL function",
! 							CreateCommandTag(stmt))));
  
! 		if (fcache->readonly_func && !CommandIsReadOnly(stmt))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 			/* translator: %s is a SQL statement name */
! 					 errmsg("%s is not allowed in a non-volatile function",
! 							CreateCommandTag(stmt))));
  
! 		newes = (execution_state *) palloc(sizeof(execution_state));
! 		if (preves)
! 			preves->next = newes;
! 		else
! 			firstes = newes;
  
! 		newes->next = NULL;
! 		newes->status = F_EXEC_START;
! 		newes->setsResult = false;		/* might change below */
! 		newes->lazyEval = false;	/* might change below */
! 		newes->stmt = stmt;
! 		newes->qd = NULL;
  
! 		if (queryTree->canSetTag)
! 			lasttages = newes;
  
! 		preves = newes;
  	}
  
  	/*
--- 123,200 ----
  
  
  /* Set up the list of per-query execution_state records for a SQL function */
! static List *
  init_execution_state(List *queryTree_list,
  					 SQLFunctionCachePtr fcache,
  					 bool lazyEvalOK)
  {
! 	execution_state *firstes;
! 	execution_state *preves;
  	execution_state *lasttages = NULL;
! 	List	   *eslist;
! 	ListCell   *lc1;
! 	ListCell   *lc2;
! 	List	   *qtlist;
! 	Query	   *queryTree;
! 
! 
! 	eslist = NIL;
  
! 	foreach(lc1, queryTree_list)
  	{
! 		qtlist = (List *) lfirst(lc1);
! 		firstes = NULL;
! 		preves = NULL;
  
! 		foreach(lc2, qtlist)
! 		{
! 			Node	   *stmt;
! 			execution_state *newes;
  
! 			queryTree = (Query *) lfirst(lc2);
  
! 			Assert(IsA(queryTree, Query));
  
! 			if (queryTree->commandType == CMD_UTILITY)
! 				stmt = queryTree->utilityStmt;
! 			else
! 				stmt = (Node *) pg_plan_query(queryTree, 0, NULL);
  
! 			/* Precheck all commands for validity in a function */
! 			if (IsA(stmt, TransactionStmt))
! 				ereport(ERROR,
! 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 				/* translator: %s is a SQL statement name */
! 						 errmsg("%s is not allowed in a SQL function",
! 								CreateCommandTag(stmt))));
  
! 			if (fcache->readonly_func && !CommandIsReadOnly(stmt))
! 				ereport(ERROR,
! 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 				/* translator: %s is a SQL statement name */
! 						 errmsg("%s is not allowed in a non-volatile function",
! 								CreateCommandTag(stmt))));
! 
! 			newes = (execution_state *) palloc(sizeof(execution_state));
! 			if (preves)
! 				preves->next = newes;
! 			else
! 				firstes = newes;
  
! 			newes->next = NULL;
! 			newes->status = F_EXEC_START;
! 			newes->setsResult = false;		/* might change below */
! 			newes->lazyEval = false;	/* might change below */
! 			newes->stmt = stmt;
! 			newes->qd = NULL;
  
! 			if (queryTree->canSetTag)
! 				lasttages = newes;
! 
! 			preves = newes;
! 		}
! 
! 		eslist = lappend(eslist, firstes);
  	}
  
  	/*
***************
*** 210,216 **** init_execution_state(List *queryTree_list,
  		}
  	}
  
! 	return firstes;
  }
  
  /* Initialize the SQLFunctionCache for a SQL function */
--- 227,233 ----
  		}
  	}
  
! 	return eslist;
  }
  
  /* Initialize the SQLFunctionCache for a SQL function */
***************
*** 342,348 **** init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK)
  	 */
  	fcache->returnsTuple = check_sql_fn_retval(foid,
  											   rettype,
! 											   queryTree_list,
  											   NULL,
  											   &fcache->junkFilter);
  
--- 359,365 ----
  	 */
  	fcache->returnsTuple = check_sql_fn_retval(foid,
  											   rettype,
! 											   llast(queryTree_list),
  											   NULL,
  											   &fcache->junkFilter);
  
***************
*** 374,397 **** init_sql_fcache(FmgrInfo *finfo, bool lazyEvalOK)
  static void
  postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  {
- 	Snapshot	snapshot;
  	DestReceiver *dest;
  
  	Assert(es->qd == NULL);
  
! 	/*
! 	 * In a read-only function, use the surrounding query's snapshot;
! 	 * otherwise take a new snapshot for each query.  The snapshot should
! 	 * include a fresh command ID so that all work to date in this transaction
! 	 * is visible.
! 	 */
! 	if (fcache->readonly_func)
! 		snapshot = GetActiveSnapshot();
! 	else
! 	{
! 		CommandCounterIncrement();
! 		snapshot = GetTransactionSnapshot();
! 	}
  
  	/*
  	 * If this query produces the function result, send its output to the
--- 391,401 ----
  static void
  postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  {
  	DestReceiver *dest;
  
  	Assert(es->qd == NULL);
  
! 	Assert(ActiveSnapshotSet());
  
  	/*
  	 * If this query produces the function result, send its output to the
***************
*** 415,427 **** postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
  	if (IsA(es->stmt, PlannedStmt))
  		es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
  								 fcache->src,
! 								 snapshot, InvalidSnapshot,
  								 dest,
  								 fcache->paramLI, 0);
  	else
  		es->qd = CreateUtilityQueryDesc(es->stmt,
  										fcache->src,
! 										snapshot,
  										dest,
  										fcache->paramLI);
  
--- 419,432 ----
  	if (IsA(es->stmt, PlannedStmt))
  		es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
  								 fcache->src,
! 								 GetActiveSnapshot(),
! 								 InvalidSnapshot,
  								 dest,
  								 fcache->paramLI, 0);
  	else
  		es->qd = CreateUtilityQueryDesc(es->stmt,
  										fcache->src,
! 										GetActiveSnapshot(),
  										dest,
  										fcache->paramLI);
  
***************
*** 617,622 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 622,629 ----
  	execution_state *es;
  	TupleTableSlot *slot;
  	Datum		result;
+ 	List		*eslist;
+ 	ListCell    *eslc;
  
  	/*
  	 * Switch to context in which the fcache lives.  This ensures that
***************
*** 668,680 **** fmgr_sql(PG_FUNCTION_ARGS)
  		init_sql_fcache(fcinfo->flinfo, lazyEvalOK);
  		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
  	}
! 	es = fcache->func_state;
  
  	/*
  	 * Convert params to appropriate format if starting a fresh execution. (If
  	 * continuing execution, we can re-use prior params.)
  	 */
! 	if (es && es->status == F_EXEC_START)
  		postquel_sub_params(fcache, fcinfo);
  
  	/*
--- 675,687 ----
  		init_sql_fcache(fcinfo->flinfo, lazyEvalOK);
  		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
  	}
! 	eslist = fcache->func_state;
  
  	/*
  	 * Convert params to appropriate format if starting a fresh execution. (If
  	 * continuing execution, we can re-use prior params.)
  	 */
! 	if (linitial(eslist) && ((execution_state *) linitial(eslist))->status == F_EXEC_START)
  		postquel_sub_params(fcache, fcinfo);
  
  	/*
***************
*** 687,694 **** fmgr_sql(PG_FUNCTION_ARGS)
  	/*
  	 * Find first unfinished query in function.
  	 */
! 	while (es && es->status == F_EXEC_DONE)
! 		es = es->next;
  
  	/*
  	 * Execute each command in the function one after another until we either
--- 694,709 ----
  	/*
  	 * Find first unfinished query in function.
  	 */
! 	foreach(eslc, eslist)
! 	{
! 		es = (execution_state *) lfirst(eslc);
! 
! 		while (es && es->status == F_EXEC_DONE)
! 			es = es->next;
! 
! 		if (es)
! 			break;
! 	}
  
  	/*
  	 * Execute each command in the function one after another until we either
***************
*** 699,706 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 714,744 ----
  		bool		completed;
  
  		if (es->status == F_EXEC_START)
+ 		{
+ 			if (!fcache->readonly_func)
+ 			{
+ 				/*
+ 				 * In a read-only function, use the surrounding query's snapshot;
+ 				 * otherwise take a new snapshot if we don't have one yet.  The
+ 				 * snapshot should include a fresh command ID so that all work to
+ 				 * date in this transaction is visible.
+ 				 */
+ 				if (!fcache->snapshot)
+ 				{
+ 					CommandCounterIncrement();
+ 					fcache->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+ 					PushActiveSnapshot(fcache->snapshot);
+ 				}
+ 				else
+ 					PushUpdatedSnapshot(fcache->snapshot);
+ 			}
+ 			
  			postquel_start(es, fcache);
  
+ 			if (!fcache->readonly_func)
+ 				PopActiveSnapshot();
+ 		}
+ 
  		completed = postquel_getnext(es, fcache);
  
  		/*
***************
*** 726,731 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 764,788 ----
  		if (es->status != F_EXEC_DONE)
  			break;
  		es = es->next;
+ 
+ 		if (!es)
+ 		{
+ 			eslc = lnext(eslc);
+ 			if (!eslc)
+ 				break;
+ 
+ 			es = (execution_state *) lfirst(eslc);
+ 
+ 			/* make sure we take a new snapshot for this query list */
+ 			if (!fcache->readonly_func)
+ 			{
+ 				Assert(fcache->snapshot != InvalidSnapshot);
+ 				UnregisterSnapshot(fcache->snapshot);
+ 				fcache->snapshot = InvalidSnapshot;
+ 			}
+ 			else
+ 				Assert(fcache->snapshot == InvalidSnapshot);
+ 		}
  	}
  
  	/*
***************
*** 794,799 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 851,861 ----
  											  PointerGetDatum(fcache));
  				fcache->shutdown_reg = false;
  			}
+ 
+ 			/* Unregister snapshot if we have one */
+ 			if (fcache->snapshot != InvalidSnapshot)
+ 				UnregisterSnapshot(fcache->snapshot);
+ 			fcache->snapshot = InvalidSnapshot;
  		}
  		else
  		{
***************
*** 820,825 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 882,892 ----
  											  PointerGetDatum(fcache));
  				fcache->shutdown_reg = false;
  			}
+ 
+ 			/* Unregister snapshot if we have one */
+ 			if (fcache->snapshot != InvalidSnapshot)
+ 				UnregisterSnapshot(fcache->snapshot);
+ 			fcache->snapshot = InvalidSnapshot;
  		}
  	}
  	else
***************
*** 850,855 **** fmgr_sql(PG_FUNCTION_ARGS)
--- 917,927 ----
  
  		/* Clear the tuplestore, but keep it for next time */
  		tuplestore_clear(fcache->tstore);
+ 
+ 		/* Unregister snapshot if we have one */
+ 		if (fcache->snapshot != InvalidSnapshot)
+ 			UnregisterSnapshot(fcache->snapshot);
+ 		fcache->snapshot = InvalidSnapshot;
  	}
  
  	/*
***************
*** 858,868 **** fmgr_sql(PG_FUNCTION_ARGS)
  	 */
  	if (es == NULL)
  	{
! 		es = fcache->func_state;
! 		while (es)
  		{
! 			es->status = F_EXEC_START;
! 			es = es->next;
  		}
  	}
  
--- 930,943 ----
  	 */
  	if (es == NULL)
  	{
! 		foreach(eslc, fcache->func_state)
  		{
! 			es = (execution_state *) lfirst(eslc);
! 			while (es)
! 			{
! 				es->status = F_EXEC_START;
! 				es = es->next;
! 			}
  		}
  	}
  
***************
*** 913,931 **** sql_exec_error_callback(void *arg)
  	{
  		execution_state *es;
  		int			query_num;
  
- 		es = fcache->func_state;
  		query_num = 1;
! 		while (es)
  		{
! 			if (es->qd)
  			{
! 				errcontext("SQL function \"%s\" statement %d",
! 						   fcache->fname, query_num);
! 				break;
  			}
- 			es = es->next;
- 			query_num++;
  		}
  		if (es == NULL)
  		{
--- 988,1011 ----
  	{
  		execution_state *es;
  		int			query_num;
+ 		ListCell   *lc;
  
  		query_num = 1;
! 
! 		foreach(lc, fcache->func_state)
  		{
! 			es = (execution_state *) lfirst(lc);
! 			while (es)
  			{
! 				if (es->qd)
! 				{
! 					errcontext("SQL function \"%s\" statement %d",
! 							   fcache->fname, query_num);
! 					break;
! 				}
! 				es = es->next;
! 				query_num++;
  			}
  		}
  		if (es == NULL)
  		{
***************
*** 956,973 **** static void
  ShutdownSQLFunction(Datum arg)
  {
  	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
! 	execution_state *es = fcache->func_state;
  
! 	while (es != NULL)
  	{
! 		/* Shut down anything still running */
! 		if (es->status == F_EXEC_RUN)
! 			postquel_end(es);
! 		/* Reset states to START in case we're called again */
! 		es->status = F_EXEC_START;
! 		es = es->next;
  	}
  
  	/* Release tuplestore if we have one */
  	if (fcache->tstore)
  		tuplestore_end(fcache->tstore);
--- 1036,1064 ----
  ShutdownSQLFunction(Datum arg)
  {
  	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
! 	execution_state *es;
! 	ListCell		*lc;
  
! 	foreach(lc, fcache->func_state)
  	{
! 		es = (execution_state *) lfirst(lc);
! 
! 		while (es)
! 		{
! 			/* Shut down anything still running */
! 			if (es->status == F_EXEC_RUN)
! 				postquel_end(es);
! 			/* Reset states to START in case we're called again */
! 			es->status = F_EXEC_START;
! 			es = es->next;
! 		}
  	}
  
+ 	/* Unregister snapshot if we have one */
+ 	if (fcache->snapshot != InvalidSnapshot)
+ 		UnregisterSnapshot(fcache->snapshot);
+ 	fcache->snapshot = InvalidSnapshot;
+ 
  	/* Release tuplestore if we have one */
  	if (fcache->tstore)
  		tuplestore_end(fcache->tstore);
*** a/src/backend/executor/spi.c
--- b/src/backend/executor/spi.c
***************
*** 1769,1774 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
--- 1769,1775 ----
  	SPITupleTable *my_tuptable = NULL;
  	int			res = 0;
  	bool		have_active_snap = ActiveSnapshotSet();
+ 	bool		registered_snap = false;
  	ErrorContextCallback spierrcontext;
  	CachedPlan *cplan = NULL;
  	ListCell   *lc1;
***************
*** 1872,1879 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
  				}
  				else
  				{
! 					PushActiveSnapshot(GetTransactionSnapshot());
  					pushed_active_snap = true;
  				}
  			}
  			else
--- 1873,1882 ----
  				}
  				else
  				{
! 					snapshot = RegisterSnapshot(GetTransactionSnapshot());
! 					PushActiveSnapshot(snapshot);
  					pushed_active_snap = true;
+ 					registered_snap = true;
  				}
  			}
  			else
***************
*** 1966,1975 **** _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
--- 1969,1991 ----
  		 */
  		if (!read_only)
  			CommandCounterIncrement();
+ 
+ 		/*
+ 		 * If we took a new snapshot for this query list, unregister it and
+ 		 * make sure we take a new one for the next list.
+ 		 */
+ 		if (registered_snap)
+ 		{
+ 			UnregisterSnapshot(snapshot);
+ 			snapshot = InvalidSnapshot;
+ 		}
  	}
  
  fail:
  
+ 	if (registered_snap)
+ 		UnregisterSnapshot(snapshot);
+ 
  	/* We no longer need the cached plan refcount, if any */
  	if (cplan)
  		ReleaseCachedPlan(cplan, true);
*** a/src/backend/tcop/postgres.c
--- b/src/backend/tcop/postgres.c
***************
*** 537,547 **** pg_parse_and_rewrite(const char *query_string,	/* string to execute */
  	{
  		Node	   *parsetree = (Node *) lfirst(list_item);
  
! 		querytree_list = list_concat(querytree_list,
! 									 pg_analyze_and_rewrite(parsetree,
! 															query_string,
! 															paramTypes,
! 															numParams));
  	}
  
  	return querytree_list;
--- 537,547 ----
  	{
  		Node	   *parsetree = (Node *) lfirst(list_item);
  
! 		querytree_list = lappend(querytree_list,
! 								 pg_analyze_and_rewrite(parsetree,
! 														query_string,
! 														paramTypes,
! 														numParams));
  	}
  
  	return querytree_list;
*** a/src/backend/tcop/pquery.c
--- b/src/backend/tcop/pquery.c
***************
*** 170,180 **** ProcessQuery(PlannedStmt *plan,
  	elog(DEBUG3, "ProcessQuery");
  
  	/*
- 	 * Must always set a snapshot for plannable queries.
- 	 */
- 	PushActiveSnapshot(GetTransactionSnapshot());
- 
- 	/*
  	 * Create the QueryDesc object
  	 */
  	queryDesc = CreateQueryDesc(plan, sourceText,
--- 170,175 ----
***************
*** 234,241 **** ProcessQuery(PlannedStmt *plan,
  	/* Now take care of any queued AFTER triggers */
  	AfterTriggerEndQuery(queryDesc->estate);
  
- 	PopActiveSnapshot();
- 
  	/*
  	 * Now, we close down all the scans and free allocated resources.
  	 */
--- 229,234 ----
***************
*** 1220,1225 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1213,1219 ----
  			   char *completionTag)
  {
  	ListCell   *stmtlist_item;
+ 	Snapshot	snapshot = InvalidSnapshot;
  
  	/*
  	 * If the destination is DestRemoteExecute, change to DestNone.  The
***************
*** 1262,1267 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1256,1270 ----
  			if (log_executor_stats)
  				ResetUsage();
  
+ 			/* if no snapshot is set, grab a new one and register it */
+ 			if (snapshot == InvalidSnapshot)
+ 			{
+ 				snapshot = RegisterSnapshot(GetTransactionSnapshot());
+ 				PushActiveSnapshot(snapshot);
+ 			}
+ 			else
+ 				PushUpdatedSnapshot(snapshot);
+ 
  			if (pstmt->canSetTag)
  			{
  				/* statement can set tag string */
***************
*** 1279,1284 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1282,1289 ----
  							 altdest, NULL);
  			}
  
+ 			PopActiveSnapshot();
+ 
  			if (log_executor_stats)
  				ShowUsage("EXECUTOR STATISTICS");
  
***************
*** 1291,1301 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1296,1320 ----
  			 *
  			 * These are assumed canSetTag if they're the only stmt in the
  			 * portal.
+ 			 *
+ 			 * NotifyStmt is the only utility statement allowed in a list of
+ 			 * rewritten queries, and it doesn't need a snapshot so we don't
+ 			 * need to worry about it.  However, if the list has only one
+ 			 * statement and it's a utility statement, we are not allowed to
+ 			 * take a snapshot.  See the first comment in PortalRunUtility().
  			 */
  			if (list_length(portal->stmts) == 1)
+ 			{
+ 				Assert(snapshot == InvalidSnapshot);
+ 
  				PortalRunUtility(portal, stmt, isTopLevel, dest, completionTag);
+ 			}
  			else
+ 			{
+ 				Assert(IsA(stmt, NotifyStmt));
+ 
  				PortalRunUtility(portal, stmt, isTopLevel, altdest, NULL);
+ 			}
  		}
  
  		/*
***************
*** 1313,1318 **** PortalRunMulti(Portal portal, bool isTopLevel,
--- 1332,1340 ----
  		MemoryContextDeleteChildren(PortalGetHeapMemory(portal));
  	}
  
+ 	if (snapshot != InvalidSnapshot)
+ 		UnregisterSnapshot(snapshot);
+ 
  	/*
  	 * If a command completion tag was supplied, use it.  Otherwise use the
  	 * portal's commandTag as the default completion tag.