From 6de6d96d971c76c8d7bd3b31e6f182906137f913 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 16 Oct 2015 11:31:23 -0400
Subject: [PATCH] Invalidate caches after cranking up a parallel worker
 transaction.

Starting a parallel worker transaction changes our notion of which XIDs
are in-progress or committed, and our notion of the current command
counter ID.  Therefore, our view of these caches prior to starting
this transaction may no longer valid.  Defend against that by clearing
them.

This fixes a bug in commit 924bcf4f16d54c55310b28f77686608684734f42.
---
 src/backend/access/transam/parallel.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 0b94c0f87e9..e09bdb20b0d 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -28,6 +28,7 @@
 #include "tcop/tcopprot.h"
 #include "utils/combocid.h"
 #include "utils/guc.h"
+#include "utils/inval.h"
 #include "utils/memutils.h"
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
@@ -928,6 +929,12 @@ ParallelWorkerMain(Datum main_arg)
 	Assert(asnapspace != NULL);
 	PushActiveSnapshot(RestoreSnapshot(asnapspace));
 
+	/*
+	 * We've changed which tuples we can see, and must therefore invalidate
+	 * system caches.
+	 */
+	InvalidateSystemCaches();
+
 	/* Restore user ID and security context. */
 	SetUserIdAndSecContext(fps->current_user_id, fps->sec_context);
 
-- 
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