diff --git a/contrib/auto_explain/auto_explain.c b/contrib/auto_explain/auto_explain.c
index 34b9f1543e..9213ffb6a4 100644
--- a/contrib/auto_explain/auto_explain.c
+++ b/contrib/auto_explain/auto_explain.c
@@ -61,7 +61,7 @@ void		_PG_fini(void);
 static void explain_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void explain_ExecutorRun(QueryDesc *queryDesc,
 					ScanDirection direction,
-					uint64 count);
+					uint64 count, bool execute_once);
 static void explain_ExecutorFinish(QueryDesc *queryDesc);
 static void explain_ExecutorEnd(QueryDesc *queryDesc);
 
@@ -257,15 +257,16 @@ explain_ExecutorStart(QueryDesc *queryDesc, int eflags)
  * ExecutorRun hook: all we need do is track nesting depth
  */
 static void
-explain_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count)
+explain_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction,
+					uint64 count, bool execute_once)
 {
 	nesting_level++;
 	PG_TRY();
 	{
 		if (prev_ExecutorRun)
-			prev_ExecutorRun(queryDesc, direction, count);
+			prev_ExecutorRun(queryDesc, direction, count, execute_once);
 		else
-			standard_ExecutorRun(queryDesc, direction, count);
+			standard_ExecutorRun(queryDesc, direction, count, execute_once);
 		nesting_level--;
 	}
 	PG_CATCH();
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 221ac98d4a..42f43233f8 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,7 +290,7 @@ static void pgss_post_parse_analyze(ParseState *pstate, Query *query);
 static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void pgss_ExecutorRun(QueryDesc *queryDesc,
 				 ScanDirection direction,
-				 uint64 count);
+				 uint64 count, bool execute_once);
 static void pgss_ExecutorFinish(QueryDesc *queryDesc);
 static void pgss_ExecutorEnd(QueryDesc *queryDesc);
 static void pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
@@ -871,15 +871,16 @@ pgss_ExecutorStart(QueryDesc *queryDesc, int eflags)
  * ExecutorRun hook: all we need do is track nesting depth
  */
 static void
-pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count)
+pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count,
+				 bool execute_once)
 {
 	nested_level++;
 	PG_TRY();
 	{
 		if (prev_ExecutorRun)
-			prev_ExecutorRun(queryDesc, direction, count);
+			prev_ExecutorRun(queryDesc, direction, count, execute_once);
 		else
-			standard_ExecutorRun(queryDesc, direction, count);
+			standard_ExecutorRun(queryDesc, direction, count, execute_once);
 		nested_level--;
 	}
 	PG_CATCH();
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index ba89b292d1..54aba9156a 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -2067,7 +2067,7 @@ CopyTo(CopyState cstate)
 	else
 	{
 		/* run the plan --- the dest receiver will send tuples */
-		ExecutorRun(cstate->queryDesc, ForwardScanDirection, 0L);
+		ExecutorRun(cstate->queryDesc, ForwardScanDirection, 0L, true);
 		processed = ((DR_copy *) cstate->queryDesc->dest)->processed;
 	}
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 646a88409f..3daffc894a 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -347,7 +347,7 @@ ExecCreateTableAs(CreateTableAsStmt *stmt, const char *queryString,
 		ExecutorStart(queryDesc, GetIntoRelEFlags(into));
 
 		/* run the plan to completion */
-		ExecutorRun(queryDesc, ForwardScanDirection, 0L);
+		ExecutorRun(queryDesc, ForwardScanDirection, 0L, true);
 
 		/* save the rowcount if we're given a completionTag to fill */
 		if (completionTag)
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index c9b55ead3d..b4c7466666 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -530,7 +530,7 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
 			dir = ForwardScanDirection;
 
 		/* run the plan */
-		ExecutorRun(queryDesc, dir, 0L);
+		ExecutorRun(queryDesc, dir, 0L, true);
 
 		/* run cleanup too */
 		ExecutorFinish(queryDesc);
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index 86a84ee234..5a84bedf46 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -742,7 +742,7 @@ execute_sql_string(const char *sql, const char *filename)
 										dest, NULL, 0);
 
 				ExecutorStart(qdesc, 0);
-				ExecutorRun(qdesc, ForwardScanDirection, 0);
+				ExecutorRun(qdesc, ForwardScanDirection, 0, true);
 				ExecutorFinish(qdesc);
 				ExecutorEnd(qdesc);
 
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index a18c917336..ad39df2024 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -404,7 +404,7 @@ refresh_matview_datafill(DestReceiver *dest, Query *query,
 	ExecutorStart(queryDesc, EXEC_FLAG_WITHOUT_OIDS);
 
 	/* run the plan */
-	ExecutorRun(queryDesc, ForwardScanDirection, 0L);
+	ExecutorRun(queryDesc, ForwardScanDirection, 0L, true);
 
 	/* and clean up */
 	ExecutorFinish(queryDesc);
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index 29d0430dd8..f57cf87e8c 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -395,7 +395,7 @@ PersistHoldablePortal(Portal portal)
 										true);
 
 		/* Fetch the result set into the tuplestore */
-		ExecutorRun(queryDesc, ForwardScanDirection, 0L);
+		ExecutorRun(queryDesc, ForwardScanDirection, 0L, false);
 
 		(*queryDesc->dest->rDestroy) (queryDesc->dest);
 		queryDesc->dest = NULL;
diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index 1cf0d2b971..992ba1c9a2 100644
--- a/src/backend/commands/prepare.c
+++ b/src/backend/commands/prepare.c
@@ -301,7 +301,7 @@ ExecuteQuery(ExecuteStmt *stmt, IntoClause *intoClause,
 	 */
 	PortalStart(portal, paramLI, eflags, GetActiveSnapshot());
 
-	(void) PortalRun(portal, count, false, dest, dest, completionTag);
+	(void) PortalRun(portal, count, false, true, dest, dest, completionTag);
 
 	PortalDrop(portal, false);
 
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index f5cd65d8a0..4f5b7b3bca 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -85,7 +85,8 @@ static void ExecutePlan(EState *estate, PlanState *planstate,
 			bool sendTuples,
 			uint64 numberTuples,
 			ScanDirection direction,
-			DestReceiver *dest);
+			DestReceiver *dest,
+			bool execute_once);
 static bool ExecCheckRTEPerms(RangeTblEntry *rte);
 static bool ExecCheckRTEPermsModified(Oid relOid, Oid userid,
 						  Bitmapset *modifiedCols,
@@ -288,17 +289,18 @@ standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
  */
 void
 ExecutorRun(QueryDesc *queryDesc,
-			ScanDirection direction, uint64 count)
+			ScanDirection direction, uint64 count,
+			bool execute_once)
 {
 	if (ExecutorRun_hook)
-		(*ExecutorRun_hook) (queryDesc, direction, count);
+		(*ExecutorRun_hook) (queryDesc, direction, count, execute_once);
 	else
-		standard_ExecutorRun(queryDesc, direction, count);
+		standard_ExecutorRun(queryDesc, direction, count, execute_once);
 }
 
 void
 standard_ExecutorRun(QueryDesc *queryDesc,
-					 ScanDirection direction, uint64 count)
+					 ScanDirection direction, uint64 count, bool execute_once)
 {
 	EState	   *estate;
 	CmdType		operation;
@@ -345,6 +347,11 @@ standard_ExecutorRun(QueryDesc *queryDesc,
 	 * run plan
 	 */
 	if (!ScanDirectionIsNoMovement(direction))
+	{
+		if (execute_once && queryDesc->already_executed)
+			elog(ERROR, "can't re-execute query flagged for single execution");
+		queryDesc->already_executed = true;
+
 		ExecutePlan(estate,
 					queryDesc->planstate,
 					queryDesc->plannedstmt->parallelModeNeeded,
@@ -352,7 +359,9 @@ standard_ExecutorRun(QueryDesc *queryDesc,
 					sendTuples,
 					count,
 					direction,
-					dest);
+					dest,
+					execute_once);
+	}
 
 	/*
 	 * shutdown tuple receiver, if we started it
@@ -1575,7 +1584,8 @@ ExecutePlan(EState *estate,
 			bool sendTuples,
 			uint64 numberTuples,
 			ScanDirection direction,
-			DestReceiver *dest)
+			DestReceiver *dest,
+			bool execute_once)
 {
 	TupleTableSlot *slot;
 	uint64		current_tuple_count;
@@ -1591,12 +1601,12 @@ ExecutePlan(EState *estate,
 	estate->es_direction = direction;
 
 	/*
-	 * If a tuple count was supplied, we must force the plan to run without
-	 * parallelism, because we might exit early.  Also disable parallelism
-	 * when writing into a relation, because no database changes are allowed
-	 * in parallel mode.
+	 * If the plan might potentially be executed multiple times, we must force
+	 * it to run without parallelism, because we might exit early.  Also
+	 * disable parallelism when writing into a relation, because no database
+	 * changes are allowed in parallel mode.
 	 */
-	if (numberTuples || dest->mydest == DestIntoRel)
+	if (!execute_once || dest->mydest == DestIntoRel)
 		use_parallel_mode = false;
 
 	if (use_parallel_mode)
@@ -1667,7 +1677,11 @@ ExecutePlan(EState *estate,
 		 */
 		current_tuple_count++;
 		if (numberTuples && numberTuples == current_tuple_count)
+		{
+			/* Allow nodes to release or shut down resources. */
+			(void) ExecShutdownNode(planstate);
 			break;
+		}
 	}
 
 	if (use_parallel_mode)
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index a1289e5f12..948a9194d5 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -852,7 +852,7 @@ ParallelQueryMain(dsm_segment *seg, shm_toc *toc)
 	ExecParallelInitializeWorker(queryDesc->planstate, toc);
 
 	/* Run the plan */
-	ExecutorRun(queryDesc, ForwardScanDirection, 0L);
+	ExecutorRun(queryDesc, ForwardScanDirection, 0L, true);
 
 	/* Shut down the executor */
 	ExecutorFinish(queryDesc);
diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 2d49a65650..98963a367a 100644
--- a/src/backend/executor/functions.c
+++ b/src/backend/executor/functions.c
@@ -855,7 +855,7 @@ postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)
 		/* Run regular commands to completion unless lazyEval */
 		uint64		count = (es->lazyEval) ? 1 : 0;
 
-		ExecutorRun(es->qd, ForwardScanDirection, count);
+		ExecutorRun(es->qd, ForwardScanDirection, count, !fcache->returnsSet);
 
 		/*
 		 * If we requested run to completion OR there was no tuple returned,
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 55f97b14e6..72c7b4d068 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -2305,7 +2305,7 @@ _SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount)
 
 	ExecutorStart(queryDesc, eflags);
 
-	ExecutorRun(queryDesc, ForwardScanDirection, tcount);
+	ExecutorRun(queryDesc, ForwardScanDirection, tcount, true);
 
 	_SPI_current->processed = queryDesc->estate->es_processed;
 	_SPI_current->lastoid = queryDesc->estate->es_lastoid;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index b07d6c6cb9..707e7c385d 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1101,6 +1101,7 @@ exec_simple_query(const char *query_string)
 		(void) PortalRun(portal,
 						 FETCH_ALL,
 						 isTopLevel,
+						 true,
 						 receiver,
 						 receiver,
 						 completionTag);
@@ -1985,6 +1986,7 @@ exec_execute_message(const char *portal_name, long max_rows)
 	completed = PortalRun(portal,
 						  max_rows,
 						  true, /* always top level */
+						  !execute_is_fetch && max_rows == FETCH_ALL,
 						  receiver,
 						  receiver,
 						  completionTag);
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index 371d7350b7..f538b7787c 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -90,6 +90,9 @@ CreateQueryDesc(PlannedStmt *plannedstmt,
 	qd->planstate = NULL;
 	qd->totaltime = NULL;
 
+	/* not yet executed */
+	qd->already_executed = false;
+
 	return qd;
 }
 
@@ -152,7 +155,7 @@ ProcessQuery(PlannedStmt *plan,
 	/*
 	 * Run the plan to completion.
 	 */
-	ExecutorRun(queryDesc, ForwardScanDirection, 0L);
+	ExecutorRun(queryDesc, ForwardScanDirection, 0L, true);
 
 	/*
 	 * Build command completion status string, if caller wants one.
@@ -679,7 +682,7 @@ PortalSetResultFormat(Portal portal, int nFormats, int16 *formats)
  * suspended due to exhaustion of the count parameter.
  */
 bool
-PortalRun(Portal portal, long count, bool isTopLevel,
+PortalRun(Portal portal, long count, bool isTopLevel, bool run_once,
 		  DestReceiver *dest, DestReceiver *altdest,
 		  char *completionTag)
 {
@@ -712,6 +715,10 @@ PortalRun(Portal portal, long count, bool isTopLevel,
 	 */
 	MarkPortalActive(portal);
 
+	/* Set run_once flag.  Shouldn't be clear if previously set. */
+	Assert(!portal->run_once || run_once);
+	portal->run_once = run_once;
+
 	/*
 	 * Set up global portal context pointers.
 	 *
@@ -918,7 +925,8 @@ PortalRunSelect(Portal portal,
 		else
 		{
 			PushActiveSnapshot(queryDesc->snapshot);
-			ExecutorRun(queryDesc, direction, (uint64) count);
+			ExecutorRun(queryDesc, direction, (uint64) count,
+						portal->run_once);
 			nprocessed = queryDesc->estate->es_processed;
 			PopActiveSnapshot();
 		}
@@ -957,7 +965,8 @@ PortalRunSelect(Portal portal,
 		else
 		{
 			PushActiveSnapshot(queryDesc->snapshot);
-			ExecutorRun(queryDesc, direction, (uint64) count);
+			ExecutorRun(queryDesc, direction, (uint64) count,
+						portal->run_once);
 			nprocessed = queryDesc->estate->es_processed;
 			PopActiveSnapshot();
 		}
@@ -1394,6 +1403,9 @@ PortalRunFetch(Portal portal,
 	 */
 	MarkPortalActive(portal);
 
+	/* If supporting FETCH, portal can't be run-once. */
+	Assert(!portal->run_once);
+
 	/*
 	 * Set up global portal context pointers.
 	 */
diff --git a/src/include/executor/execdesc.h b/src/include/executor/execdesc.h
index c99ea81815..87e7ca8508 100644
--- a/src/include/executor/execdesc.h
+++ b/src/include/executor/execdesc.h
@@ -47,6 +47,9 @@ typedef struct QueryDesc
 	EState	   *estate;			/* executor's query-wide state */
 	PlanState  *planstate;		/* tree of per-plan-node state */
 
+	/* This field is set by ExecutorRun */
+	bool		already_executed;		/* true if previously executed */
+
 	/* This is always set NULL by the core system, but plugins can change it */
 	struct Instrumentation *totaltime;	/* total time spent in ExecutorRun */
 } QueryDesc;
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 02dbe7b228..7333569552 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -81,7 +81,8 @@ extern PGDLLIMPORT ExecutorStart_hook_type ExecutorStart_hook;
 /* Hook for plugins to get control in ExecutorRun() */
 typedef void (*ExecutorRun_hook_type) (QueryDesc *queryDesc,
 												   ScanDirection direction,
-												   uint64 count);
+												   uint64 count,
+												   bool execute_once);
 extern PGDLLIMPORT ExecutorRun_hook_type ExecutorRun_hook;
 
 /* Hook for plugins to get control in ExecutorFinish() */
@@ -176,9 +177,9 @@ extern TupleTableSlot *ExecFilterJunk(JunkFilter *junkfilter,
 extern void ExecutorStart(QueryDesc *queryDesc, int eflags);
 extern void standard_ExecutorStart(QueryDesc *queryDesc, int eflags);
 extern void ExecutorRun(QueryDesc *queryDesc,
-			ScanDirection direction, uint64 count);
+			ScanDirection direction, uint64 count, bool execute_once);
 extern void standard_ExecutorRun(QueryDesc *queryDesc,
-					 ScanDirection direction, uint64 count);
+					 ScanDirection direction, uint64 count, bool execute_once);
 extern void ExecutorFinish(QueryDesc *queryDesc);
 extern void standard_ExecutorFinish(QueryDesc *queryDesc);
 extern void ExecutorEnd(QueryDesc *queryDesc);
diff --git a/src/include/tcop/pquery.h b/src/include/tcop/pquery.h
index 61c0b3447e..12ff4588c6 100644
--- a/src/include/tcop/pquery.h
+++ b/src/include/tcop/pquery.h
@@ -34,7 +34,7 @@ extern void PortalSetResultFormat(Portal portal, int nFormats,
 					  int16 *formats);
 
 extern bool PortalRun(Portal portal, long count, bool isTopLevel,
-		  DestReceiver *dest, DestReceiver *altdest,
+		  bool run_once, DestReceiver *dest, DestReceiver *altdest,
 		  char *completionTag);
 
 extern uint64 PortalRunFetch(Portal portal,
diff --git a/src/include/utils/portal.h b/src/include/utils/portal.h
index dc76acd0a4..e7c5a8bd09 100644
--- a/src/include/utils/portal.h
+++ b/src/include/utils/portal.h
@@ -141,6 +141,7 @@ typedef struct PortalData
 	/* Features/options */
 	PortalStrategy strategy;	/* see above */
 	int			cursorOptions;	/* DECLARE CURSOR option bits */
+	bool		run_once;		/* portal will only be run once */
 
 	/* Status data */
 	PortalStatus status;		/* see above */