1 files changed, 24 insertions, 13 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 37b7bbd413b..a55022e0a80 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -76,6 +76,7 @@ static void CheckValidRowMarkRel(Relation rel, RowMarkType markType);
 static void ExecPostprocessPlan(EState *estate);
 static void ExecEndPlan(PlanState *planstate, EState *estate);
 static void ExecutePlan(EState *estate, PlanState *planstate,
+			bool use_parallel_mode,
 			CmdType operation,
 			bool sendTuples,
 			long numberTuples,
@@ -243,11 +244,6 @@ standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
 	if (!(eflags & (EXEC_FLAG_SKIP_TRIGGERS | EXEC_FLAG_EXPLAIN_ONLY)))
 		AfterTriggerBeginQuery();
 
-	/* Enter parallel mode, if required by the query. */
-	if (queryDesc->plannedstmt->parallelModeNeeded &&
-		!(eflags & EXEC_FLAG_EXPLAIN_ONLY))
-		EnterParallelMode();
-
 	MemoryContextSwitchTo(oldcontext);
 }
 
@@ -341,15 +337,13 @@ standard_ExecutorRun(QueryDesc *queryDesc,
 	if (!ScanDirectionIsNoMovement(direction))
 		ExecutePlan(estate,
 					queryDesc->planstate,
+					queryDesc->plannedstmt->parallelModeNeeded,
 					operation,
 					sendTuples,
 					count,
 					direction,
 					dest);
 
-	/* Allow nodes to release or shut down resources. */
-	(void) ExecShutdownNode(queryDesc->planstate);
-
 	/*
 	 * shutdown tuple receiver, if we started it
 	 */
@@ -482,11 +476,6 @@ standard_ExecutorEnd(QueryDesc *queryDesc)
 	 */
 	MemoryContextSwitchTo(oldcontext);
 
-	/* Exit parallel mode, if it was required by the query. */
-	if (queryDesc->plannedstmt->parallelModeNeeded &&
-		!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY))
-		ExitParallelMode();
-
 	/*
 	 * Release EState and per-query memory context.  This should release
 	 * everything the executor has allocated.
@@ -1529,6 +1518,7 @@ ExecEndPlan(PlanState *planstate, EState *estate)
 static void
 ExecutePlan(EState *estate,
 			PlanState *planstate,
+			bool use_parallel_mode,
 			CmdType operation,
 			bool sendTuples,
 			long numberTuples,
@@ -1549,6 +1539,20 @@ 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.
+	 */
+	if (numberTuples != 0)
+		use_parallel_mode = false;
+
+	/*
+	 * If a tuple count was supplied, we must force the plan to run without
+	 * parallelism, because we might exit early.
+	 */
+	if (use_parallel_mode)
+		EnterParallelMode();
+
+	/*
 	 * Loop until we've processed the proper number of tuples from the plan.
 	 */
 	for (;;)
@@ -1566,7 +1570,11 @@ ExecutePlan(EState *estate,
 		 * process so we just end the loop...
 		 */
 		if (TupIsNull(slot))
+		{
+			/* Allow nodes to release or shut down resources. */
+			(void) ExecShutdownNode(planstate);
 			break;
+		}
 
 		/*
 		 * If we have a junk filter, then project a new tuple with the junk
@@ -1603,6 +1611,9 @@ ExecutePlan(EState *estate,
 		if (numberTuples && numberTuples == current_tuple_count)
 			break;
 	}
+
+	if (use_parallel_mode)
+		ExitParallelMode();
 }