From 9adc3d08178b89a95f9e87b76743a796814aaf8f Mon Sep 17 00:00:00 2001
From: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Date: Wed, 17 Apr 2024 06:18:23 +0000
Subject: [PATCH 2/4] Alter slot option two_phase only when altering true to
 false

---
 src/backend/commands/subscriptioncmds.c       |  3 +-
 src/test/subscription/meson.build             |  1 +
 src/test/subscription/t/099_twophase_added.pl | 72 +++++++++++++++++++
 3 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 src/test/subscription/t/099_twophase_added.pl

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index 59852fd9af..955d5e4899 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -1493,7 +1493,8 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 	/*
 	 * Try to acquire the connection necessary for altering slot.
 	 */
-	if (replaces[Anum_pg_subscription_subtwophasestate - 1])
+	if (replaces[Anum_pg_subscription_subtwophasestate - 1] &&
+		!opts.twophase)
 	{
 		bool		must_use_password;
 		char	   *err;
diff --git a/src/test/subscription/meson.build b/src/test/subscription/meson.build
index bd673a9d68..9e2a458202 100644
--- a/src/test/subscription/meson.build
+++ b/src/test/subscription/meson.build
@@ -40,6 +40,7 @@ tests += {
       't/031_column_list.pl',
       't/032_subscribe_use_index.pl',
       't/033_run_as_table_owner.pl',
+      't/099_twophase_added.pl',
       't/100_bugs.pl',
     ],
   },
diff --git a/src/test/subscription/t/099_twophase_added.pl b/src/test/subscription/t/099_twophase_added.pl
new file mode 100644
index 0000000000..c13a37675a
--- /dev/null
+++ b/src/test/subscription/t/099_twophase_added.pl
@@ -0,0 +1,72 @@
+# Copyright (c) 2021-2024, PostgreSQL Global Development Group
+
+# Additional tests for altering two_phase option
+use strict;
+use warnings FATAL => 'all';
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+# Initialize publisher node
+my $node_publisher = PostgreSQL::Test::Cluster->new('publisher');
+$node_publisher->init(allows_streaming => 'logical');
+$node_publisher->append_conf('postgresql.conf',
+	qq(max_prepared_transactions = 10));
+$node_publisher->start;
+
+# Create subscriber node
+my $node_subscriber = PostgreSQL::Test::Cluster->new('subscriber');
+$node_subscriber->init;
+$node_subscriber->append_conf('postgresql.conf',
+	qq(max_prepared_transactions = 10));
+$node_subscriber->start;
+
+# Define pre-existing tables on both nodes
+$node_publisher->safe_psql('postgres',
+    "CREATE TABLE tab_full (a int PRIMARY KEY);");
+$node_subscriber->safe_psql('postgres',
+	"CREATE TABLE tab_full (a int PRIMARY KEY)");
+
+# Setup logical replication, with two_phase = off
+my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
+$node_publisher->safe_psql('postgres',
+	"CREATE PUBLICATION pub FOR ALL TABLES");
+
+$node_subscriber->safe_psql(
+	'postgres', "
+	CREATE SUBSCRIPTION sub
+	CONNECTION '$publisher_connstr' PUBLICATION pub
+	WITH (two_phase = off, copy_data = off)");
+
+######
+# Check the case that prepared transactions exist on publisher node
+######
+
+$node_publisher->safe_psql(
+	'postgres', "
+	BEGIN;
+	INSERT INTO tab_full VALUES (generate_series(1, 5));
+	PREPARE TRANSACTION 'test_prepared_tab_full';");
+
+$node_publisher->wait_for_catchup('sub');
+
+my $result = $node_subscriber->safe_psql('postgres',
+    "SELECT count(*) FROM pg_prepared_xacts;");
+is($result, q(0), "transaction is not prepared on subscriber");
+
+$node_subscriber->safe_psql(
+    'postgres', "
+    ALTER SUBSCRIPTION sub DISABLE;
+    ALTER SUBSCRIPTION sub SET (two_phase = on);
+    ALTER SUBSCRIPTION sub ENABLE;");
+
+$node_publisher->safe_psql( 'postgres',
+    "COMMIT PREPARED 'test_prepared_tab_full';");
+$node_publisher->wait_for_catchup('sub');
+
+$result = $node_subscriber->safe_psql('postgres',
+    "SELECT count(*) FROM tab_full;");
+is($result, q(5),
+   "prepared transactions done before altering can be replicated");
+
+done_testing();
-- 
2.43.0