From 79f554eaf8185a2d34dc48ba31f1a3b3cd09c185 Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Date: Tue, 25 Apr 2023 06:02:17 +0000
Subject: [PATCH v6] Add retained WAL test in 035_standby_logical_decoding.pl

Adding one test, to verify that invalidated logical slots do not lead to
retaining WAL.
---
 .../t/035_standby_logical_decoding.pl         | 69 ++++++++++++++++++-
 1 file changed, 67 insertions(+), 2 deletions(-)
 100.0% src/test/recovery/t/

diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index f6d6447412..ea9ca46995 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -495,9 +495,74 @@ $node_standby->restart;
 check_slots_conflicting_status(1);
 
 ##################################################
-# Verify that invalidated logical slots do not lead to retaining WAL
+# Verify that invalidated logical slots do not lead to retaining WAL.
 ##################################################
-# XXXXX TODO
+
+# Before removing WAL files, ensure the cascading standby catch up
+$node_standby->wait_for_replay_catchup($node_cascading_standby, $node_primary);
+
+# Get the restart_lsn from an invalidated slot
+my $restart_lsn = $node_standby->safe_psql('postgres',
+	"SELECT restart_lsn from pg_replication_slots WHERE slot_name = 'vacuum_full_activeslot' and conflicting is true;"
+);
+
+chomp($restart_lsn);
+
+# Get the WAL file name associated to this lsn on the primary
+my $walfile_name = $node_primary->safe_psql('postgres',
+	"SELECT pg_walfile_name('$restart_lsn')");
+
+chomp($walfile_name);
+
+# Check the WAL file is still on the primary
+ok(-f $node_primary->data_dir . '/pg_wal/' . $walfile_name,
+	"WAL file still on the primary");
+
+# Get the number of WAL files on the standby
+my $nb_standby_files = $node_standby->safe_psql('postgres',
+	"SELECT COUNT(*) FROM pg_ls_dir('pg_wal')");
+
+chomp($nb_standby_files);
+
+# Switch WAL files on the primary
+my @c = (1 .. $nb_standby_files);
+
+$node_primary->safe_psql('postgres', "create table retain_test(a int)");
+
+for (@c)
+{
+	$node_primary->safe_psql(
+		'postgres', "SELECT pg_switch_wal();
+                                          insert into retain_test values("
+		  . $_ . ");");
+}
+
+# Ask for a checkpoint
+$node_primary->safe_psql('postgres', 'checkpoint;');
+
+# Check that the WAL file has not been retained on the primary
+ok(!-f $node_primary->data_dir . '/pg_wal/' . $walfile_name,
+	"WAL file not on the primary anymore");
+
+# Wait for the standby to catch up
+$node_primary->wait_for_catchup($node_standby);
+
+# Generate another WAL switch, more activity and a checkpoint
+$node_primary->safe_psql(
+	'postgres', "SELECT pg_switch_wal();
+                                         insert into retain_test values(1);");
+$node_primary->safe_psql('postgres', 'checkpoint;');
+
+# Wait for the standby to catch up
+$node_primary->wait_for_catchup($node_standby);
+
+# Request a checkpoint on the standby to trigger the WAL file(s) removal
+$node_standby->safe_psql('postgres', 'checkpoint;');
+
+# Verify that the wal file has not been retained on the standby
+my $standby_walfile = $node_standby->data_dir . '/pg_wal/' . $walfile_name;
+ok( !-f "$standby_walfile",
+    "invalidated logical slots do not lead to retaining WAL");
 
 ##################################################
 # Recovery conflict: Invalidate conflicting slots, including in-use slots
-- 
2.34.1