From 187dc28154581746d82f10065cb3911215f11a1c Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Fri, 28 Nov 2025 10:50:02 +0900
Subject: [PATCH v2 2/2] add test for pg_recvlogical reconnection

---
 src/bin/pg_basebackup/t/030_pg_recvlogical.pl | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/src/bin/pg_basebackup/t/030_pg_recvlogical.pl b/src/bin/pg_basebackup/t/030_pg_recvlogical.pl
index 1b7a6f6f43f..0588f052786 100644
--- a/src/bin/pg_basebackup/t/030_pg_recvlogical.pl
+++ b/src/bin/pg_basebackup/t/030_pg_recvlogical.pl
@@ -151,4 +151,75 @@ my $result = $node->safe_psql('postgres',
 );
 is($result, 't', "failover is enabled for the new slot");
 
+# Test that when pg_recvlogical reconnects, it does not write duplicate
+# records to the output file
+my $outfile = $node->basedir . '/reconnect.out';
+
+$node->command_ok(
+	[
+		'pg_recvlogical',
+		'--slot' => 'reconnect_test',
+		'--dbname' => $node->connstr('postgres'),
+		'--create-slot',
+	],
+	'slot created for reconnection test');
+
+# Insert the first record for this test
+$node->safe_psql('postgres', 'INSERT INTO test_table VALUES (1)');
+
+my ($stdout, $stderr);
+my $recv = IPC::Run::start(
+	[
+		'pg_recvlogical',
+		'--slot' => 'reconnect_test',
+		'--dbname' => $node->connstr('postgres'),
+		'--start',
+		'--file' => $outfile,
+		'--fsync-interval' => '1',
+		'--status-interval' => '100',
+		'--verbose'
+	],
+	'>' => \$stdout,
+	'2>' => \$stderr);
+
+# Wait for pg_recvlogical to receive and write the first INSERT
+$node->poll_query_until('postgres',
+	"SELECT pg_read_file('$outfile') ~ 'INSERT'")
+  or die "Timed out while waiting for pg_recvlogical to receive first INSERT";
+
+# Terminate the walsender to force pg_recvlogical to reconnect
+my $backend_pid = $node->safe_psql('postgres',
+	"SELECT active_pid FROM pg_replication_slots WHERE slot_name = 'reconnect_test'"
+);
+$node->safe_psql('postgres', "SELECT pg_terminate_backend($backend_pid)");
+
+# Wait for pg_recvlogical to establish a new connection
+$node->poll_query_until('postgres',
+	"SELECT active_pid IS NOT NULL AND active_pid != $backend_pid FROM pg_replication_slots WHERE slot_name = 'reconnect_test'"
+) or die "Timed out while waiting for pg_recvlogical to reconnect";
+
+# Insert the second record for this test
+$node->safe_psql('postgres', 'INSERT INTO test_table VALUES (2)');
+
+# Wait for pg_recvlogical to receive and write both INSERT
+$node->poll_query_until('postgres',
+	"SELECT pg_read_file('$outfile') ~ 'INSERT.*INSERT'")
+  or die "Timed out while waiting for pg_recvlogical to receive both INSERT";
+
+$recv->signal('TERM');
+$recv->finish();
+
+my $outfiledata = slurp_file("$outfile");
+my $count = (() = $outfiledata =~ /INSERT/g);
+cmp_ok($count, '==', 2, 'pg_recvlogical has received and written two INSERT');
+
+$node->command_ok(
+	[
+		'pg_recvlogical',
+		'--slot' => 'reconnect_test',
+		'--dbname' => $node->connstr('postgres'),
+		'--drop-slot'
+	],
+	'reconnect_test slot dropped');
+
 done_testing();
-- 
2.51.2