v4-0001-amit.1.patch.txt

diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index 0e621e9996a..7fa8d9247e0 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -1288,21 +1288,17 @@ LogStandbySnapshot(void)
 
 	Assert(XLogStandbyInfoActive());
 
-	/* For testing slot invalidation */
 #ifdef USE_INJECTION_POINTS
-	if (IS_INJECTION_POINT_ATTACHED("log-running-xacts"))
+	if (IS_INJECTION_POINT_ATTACHED("skip-log-running-xacts"))
 	{
 		/*
-		 * RUNNING_XACTS could move slots's xmin forward and cause random
-		 * failures in some tests. Skip generating to avoid it.
-		 *
-		 * XXX What value should we return here? Originally this returns the
-		 * inserted location of RUNNING_XACT record. Based on that, here
-		 * returns the latest insert location for now.
+		 * This record could move slot's xmin forward during decoding, leading
+		 * to unpredictable results, so skip it when requested by the test.
 		 */
 		return GetInsertRecPtr();
 	}
 #endif
+
 	/*
 	 * Get details of any AccessExclusiveLocks being held at the moment.
 	 */
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index 96dd0340e8d..39a8797a7cb 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -246,10 +246,10 @@ sub check_for_invalidation
 # VACUUM command, $sql the sql to launch before triggering the vacuum and
 # $to_vac the relation to vacuum.
 #
-# Note that injection_point is used to avoid seeing a xl_running_xacts that
-# would advance an active replication slot's catalog_xmin. Advancing the active
-# replication slot's catalog_xmin would break some tests that expect the active
-# slot to conflict with the catalog xmin horizon.
+# Note that the injection_point avoids seeing a xl_running_xacts that could
+# advance an active replication slot's catalog_xmin. Advancing the active
+# replication slot's catalog_xmin would break some tests that expect the
+# active slot to conflict with the catalog xmin horizon.
 sub wait_until_vacuum_can_remove
 {
 	my ($vac_option, $sql, $to_vac) = @_;
@@ -257,7 +257,7 @@ sub wait_until_vacuum_can_remove
 	# Note that from this point the checkpointer and bgwriter will skip writing
 	# xl_running_xacts record.
 	$node_primary->safe_psql('testdb',
-		"SELECT injection_points_attach('log-running-xacts', 'error');");
+		"SELECT injection_points_attach('skip-log-running-xacts', 'error');");
 
 	# Get the current xid horizon,
 	my $xid_horizon = $node_primary->safe_psql('testdb',
@@ -281,7 +281,7 @@ sub wait_until_vacuum_can_remove
 
 	# Resume generating the xl_running_xacts record
 	$node_primary->safe_psql('testdb',
-		"SELECT injection_points_detach('log-running-xacts');");
+		"SELECT injection_points_detach('skip-log-running-xacts');");
 }
 
 ########################
@@ -790,13 +790,12 @@ $logstart = -s $node_standby->logfile;
 reactive_slots_change_hfs_and_wait_for_xmins('no_conflict_', 'pruning_', 0,
 	0);
 
-# Injection_point is used to avoid seeing an xl_running_xacts even here. In
-# scenario 5, we verify the case that the backend process detects the page has
-# enough tuples; thus, page pruning happens. If the record is generated just
-# before doing on-pruning, the catalog_xmin of the active slot would be
-# updated; hence, the conflict would not occur.
+# Injection_point avoids seeing an xl_running_xacts even here. This is required
+# because if it is generated between the last two updates, then the catalog_xmin
+# of the active slot could be updated, and hence, the conflict won't occur. See
+# comments atop wait_until_vacuum_can_remove.
 $node_primary->safe_psql('testdb',
-	"SELECT injection_points_attach('log-running-xacts', 'error');");
+	"SELECT injection_points_attach('skip-log-running-xacts', 'error');");
 
 # This should trigger the conflict
 $node_primary->safe_psql('testdb',
@@ -812,7 +811,7 @@ $node_primary->wait_for_replay_catchup($node_standby);
 
 # Resume generating the xl_running_xacts record
 $node_primary->safe_psql('testdb',
-	"SELECT injection_points_detach('log-running-xacts');");
+	"SELECT injection_points_detach('skip-log-running-xacts');");
 
 # Check invalidation in the logfile and in pg_stat_database_conflicts
 check_for_invalidation('pruning_', $logstart, 'with on-access pruning');