autovac-antiwrap-skip.patch

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 5c554f9465..82be8c81f3 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -248,6 +248,25 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 	if (params->options & VACOPT_DISABLE_PAGE_SKIPPING)
 		aggressive = true;
 
+	/*
+	 * When running an anti-wraparound vacuum, we expect relfrozenxid to be
+	 * old enough so as aggressive is always set.  If this is not the case,
+	 * it could be possible that another concurrent vacuum process has done
+	 * the work for this relation so that relfrozenxid in relcache has
+	 * already been moved forward enough, causing this vacuum run to be
+	 * non-aggressive.  If that happens, note that this relation no longer
+	 * needs to be vacuumed, so just skip it.
+	 */
+	if (params->is_wraparound && !aggressive)
+	{
+		ereport(LOG,
+				(errmsg_internal("found vacuum to prevent wraparound of table \"%s.%s.%s\" to be not aggressive, so skipping",
+								 get_database_name(MyDatabaseId),
+								 get_namespace_name(RelationGetNamespace(onerel)),
+								 RelationGetRelationName(onerel))));
+		return;
+	}
+
 	vacrelstats = (LVRelStats *) palloc0(sizeof(LVRelStats));
 
 	vacrelstats->old_rel_pages = onerel->rd_rel->relpages;
@@ -375,10 +394,9 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 			initStringInfo(&buf);
 			if (params->is_wraparound)
 			{
-				if (aggressive)
-					msgfmt = _("automatic aggressive vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n");
-				else
-					msgfmt = _("automatic vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n");
+				/* an anti-wraparound vacuum has to be aggressive */
+				Assert(aggressive);
+				msgfmt = _("automatic aggressive vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n");
 			}
 			else
 			{