From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 21 Nov 2016 16:09:24 +0000 (-0500)
Subject: Fix test for subplans in force-parallel mode.
X-Git-Tag: REL_10_BETA1~1386
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=f24cf960d7ae3503e21fcb59dca652575619d9d4;p=postgresql.git

Fix test for subplans in force-parallel mode.

We mustn't force parallel mode if the query has any subplans, since
ExecSerializePlan doesn't transmit them to workers.  Testing
top_plan->initPlan is inadequate because (1) there might be initPlans
attached to lower plan nodes, and (2) non-initPlan subplans don't
work either.  There's certainly room for improvement in those
restrictions, but for the moment that's what we've got.

Amit Kapila, per report from Andreas Seltenreich

Discussion: <8737im6pmh.fsf@credativ.de>
---

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index d8c5dd34d6a..a8847defba3 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -342,11 +342,11 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	 * actually a safe thing to do.  (Note: we assume adding a Material node
 	 * above did not change the parallel safety of the plan, so we can still
 	 * rely on best_path->parallel_safe.  However, that flag doesn't account
-	 * for initPlans, which render the plan parallel-unsafe.)
+	 * for subplans, which we are unable to transmit to workers presently.)
 	 */
 	if (force_parallel_mode != FORCE_PARALLEL_OFF &&
 		best_path->parallel_safe &&
-		top_plan->initPlan == NIL)
+		glob->subplans == NIL)
 	{
 		Gather	   *gather = makeNode(Gather);