Fix the testcase introduced in commit 81d20fb.

Amit Kapila · Amit Kapila · commit ae395f0f7edb · 2024-07-03T15:04:59.000+05:30
The failed test was syncing failover replication slot to standby to test that we remove such slots after the standby is converted to subscriber by pg_createsubscriber. In one of the buildfarm members, the sync of the slot failed because the LSN on the standby was before the syncslot's LSN. We need to wait for standby to catch up before trying to sync the slot with pg_sync_replication_slots(). The other buildfarm failed because autovacuum generated a xid which is replicated to the standby at some random point making slots at primary lag behind standby during slot sync. Both these failures wouldn't have occurred if we had used built-in slotsync worker as it would have waited for the standby to sync with primary but for this test, it is sufficient to use pg_sync_replication_slots(). Reported-by: Alexander Lakhin as per buildfarm Author: Kuroda Hayato Reviewed-by: Amit Kapila Backpatch-through: 17 Discussion: https://postgr.es/m/0dffca12-bf17-4a7a-334d-225569de5e6e@gmail.com Discussion: https://postgr.es/m/OSBPR01MB25528300C71FDD83EA1DCA12F5DD2@OSBPR01MB2552.jpnprd01.prod.outlook.com
diff --git a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
@@ -116,6 +116,10 @@ sub generate_db
 my $node_p = PostgreSQL::Test::Cluster->new('node_p');
 my $pconnstr = $node_p->connstr;
 $node_p->init(allows_streaming => 'logical');
+# Disable autovacuum to avoid generating xid during stats update as otherwise
+# the new XID could then be replicated to standby at some random point making
+# slots at primary lag behind standby during slot sync.
+$node_p->append_conf('postgresql.conf', 'autovacuum = off');
 $node_p->start;
 
 # Set up node F as about-to-fail node
@@ -293,6 +297,9 @@ sub generate_db
 	"SELECT pg_create_logical_replication_slot('$fslotname', 'pgoutput', false, false, true)"
 );
 $node_s->start;
+# Wait for the standby to catch up so that the standby is not lagging behind
+# the failover slot.
+$node_p->wait_for_replay_catchup($node_s);
 $node_s->safe_psql('postgres', "SELECT pg_sync_replication_slots()");
 my $result = $node_s->safe_psql('postgres',
 	"SELECT slot_name FROM pg_replication_slots WHERE slot_name = '$fslotname' AND synced AND NOT temporary"
