v6-PG16-PG17-0001-Fix-oversight-3f28b2f.patch

From 94e3522510daf853b57a1039f7db2086e3344363 Mon Sep 17 00:00:00 2001
From: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Date: Tue, 22 Apr 2025 18:57:05 +0900
Subject: [PATCH v6-PG16-PG17] Fix oversight 3f28b2f

3f28b2f introduced replorigin_reset() in apply_error_callback() in case of
elevel >= ERROR to ensure the replication origin is released from the session
before exiting the process. However, in some cases, apply_error_callback() can
be called with ERROR, but the apply worker can continue applying the logical
replication. If this happens, the worker applies changes without setting the
replication origin, which can lead to data duplication.

This commit moves replorigin_reset() to PG_CATCH() part in start_apply(). The
path can be reached only by the exiting workers
---
 src/backend/replication/logical/worker.c | 21 ++++---
 src/test/subscription/t/100_bugs.pl      | 76 ++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index 65e22306c48..db09978697f 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -416,6 +416,8 @@ static inline void reset_apply_error_context_info(void);
 static TransApplyAction get_transaction_apply_action(TransactionId xid,
 													 ParallelApplyWorkerInfo **winfo);
 
+static void replorigin_reset(int code, Datum arg);
+
 /*
  * Form the origin name for the subscription.
  *
@@ -4441,6 +4443,14 @@ start_apply(XLogRecPtr origin_startpos)
 	}
 	PG_CATCH();
 	{
+		/*
+		 * Reset the origin state to prevent the advancement of origin
+		 * progress if we fail to apply. Otherwise, this will result in
+		 * transaction loss as that transaction won't be sent again by the
+		 * server.
+		 */
+		replorigin_reset(0, (Datum) 0);
+
 		if (MySubscription->disableonerr)
 			DisableSubscriptionAndExit();
 		else
@@ -4928,23 +4938,12 @@ void
 apply_error_callback(void *arg)
 {
 	ApplyErrorCallbackArg *errarg = &apply_error_callback_arg;
-	int			elevel;
 
 	if (apply_error_callback_arg.command == 0)
 		return;
 
 	Assert(errarg->origin_name);
 
-	elevel = geterrlevel();
-
-	/*
-	 * Reset the origin state to prevent the advancement of origin progress if
-	 * we fail to apply. Otherwise, this will result in transaction loss as
-	 * that transaction won't be sent again by the server.
-	 */
-	if (elevel >= ERROR)
-		replorigin_reset(0, (Datum) 0);
-
 	if (errarg->rel == NULL)
 	{
 		if (!TransactionIdIsValid(errarg->remote_xid))
diff --git a/src/test/subscription/t/100_bugs.pl b/src/test/subscription/t/100_bugs.pl
index cb36ca7b16b..3c00e2f8867 100644
--- a/src/test/subscription/t/100_bugs.pl
+++ b/src/test/subscription/t/100_bugs.pl
@@ -490,4 +490,80 @@ is( $result, qq(2|f
 $node_publisher->stop('fast');
 $node_subscriber->stop('fast');
 
+# The bug was that when an ERROR was caught, for instance by a PL/pgSQL
+# function, the apply worker reset the replication origin but continued
+# processing subsequent changes. This behavior resulted in a failure to update
+# the replication origin during further apply operations.
+
+$node_publisher->rotate_logfile();
+$node_publisher->start();
+
+$node_subscriber->rotate_logfile();
+$node_subscriber->start();
+
+# Set up a publication with a table
+$node_publisher->safe_psql(
+	'postgres', qq(
+	CREATE TABLE t1 (a int);
+	CREATE PUBLICATION regress_pub FOR TABLE t1;
+));
+
+# Set up a subscription which subscribes the publication
+$node_subscriber->safe_psql(
+	'postgres', qq(
+	CREATE TABLE t1 (a int);
+	CREATE SUBSCRIPTION regress_sub CONNECTION '$publisher_connstr' PUBLICATION regress_pub;
+));
+
+$node_subscriber->wait_for_subscription_sync($node_publisher, 'regress_sub');
+
+# Create an AFTER INSERT trigger on the table that raises and subsequently
+# handles an exception. Subsequent insertions will trigger this exception,
+# causing the apply worker to invoke its error callback with an ERROR. However,
+# since the error is caught within the trigger, the apply worker will continue
+# processing changes.
+$node_subscriber->safe_psql(
+	'postgres', q{
+CREATE FUNCTION handle_exception_trigger()
+RETURNS TRIGGER AS $$
+BEGIN
+	BEGIN
+		-- Raise an exception
+		RAISE EXCEPTION 'This is a test exception';
+	EXCEPTION
+		WHEN OTHERS THEN
+			RETURN NEW;
+	END;
+
+	RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER silent_exception_trigger
+AFTER INSERT OR UPDATE ON t1
+FOR EACH ROW
+EXECUTE FUNCTION handle_exception_trigger();
+
+ALTER TABLE t1 ENABLE ALWAYS TRIGGER silent_exception_trigger;
+});
+
+# Obtain current remote_lsn value to check its advancement later
+my $remote_lsn = $node_subscriber->safe_psql('postgres',
+	"SELECT remote_lsn FROM pg_replication_origin_status os, pg_subscription s WHERE os.external_id = 'pg_' || s.oid AND s.subname = 'regress_sub'"
+);
+
+# Insert a tuple to replicate changes
+$node_publisher->safe_psql('postgres', "INSERT INTO t1 VALUES (1);");
+$node_publisher->wait_for_catchup('regress_sub');
+
+# Confirms the origin can be advanced
+$result = $node_subscriber->safe_psql('postgres',
+	"SELECT remote_lsn > '$remote_lsn' FROM pg_replication_origin_status os, pg_subscription s WHERE os.external_id = 'pg_' || s.oid AND s.subname = 'regress_sub'"
+);
+is($result, 't',
+	'remote_lsn has advanced for apply worker raising an exception');
+
+$node_publisher->stop('fast');
+$node_subscriber->stop('fast');
+
 done_testing();
-- 
2.43.5