v6-0002-Add-TAP-test-for-GUC-settings-passed-via-CONNECTI.patch

From 0e49936016a81eccf095cf710aa6c5ea1ca761cf Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Thu, 27 Nov 2025 12:36:59 +0900
Subject: [PATCH v6 2/2] Add TAP test for GUC settings passed via CONNECTION in
 logical replication.

This commit adds a TAP test to verify that GUC settings provided in
the CONNECTION string of CREATE/ALTER SUBSCRIPTION are correctly
passed through to and applied by the publisher's walsender.
---
 src/test/subscription/t/001_rep_changes.pl | 29 +++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..9db7e8219de 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -438,17 +438,34 @@ is( $result, qq(11.11|baz|1
 22.22|bar|2),
 	'update works with dropped subscriber column');
 
+# Verify that GUC settings supplied in the CONNECTION string take effect on
+# the publisher's walsender.  We do this by enabling log_statement_stats in
+# the CONNECTION string later and checking that the publisher's log contains a
+# QUERY STATISTICS message.
+#
+# First, confirm that no such QUERY STATISTICS message appears before enabling
+# log_statement_stats.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+unlike(
+	$logfile,
+	qr/QUERY STATISTICS/,
+	'log_statement_stats has not been enabled yet');
+
 # check that change of connection string and/or publication list causes
 # restart of subscription workers. We check the state along with
 # application_name to ensure that the walsender is (re)started.
 #
 # Not all of these are registered as tests as we need to poll for a change
 # but the test suite will fail nonetheless when something goes wrong.
+#
+# Enable log_statement_stats as the change of connection string,
+# which is also for the above mentioned test of GUC settings passed through
+# CONNECTION.
 my $oldpid = $node_publisher->safe_psql('postgres',
 	"SELECT pid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
 );
 $node_subscriber->safe_psql('postgres',
-	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr sslmode=disable'"
+	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr options=''-c log_statement_stats=on'''"
 );
 $node_publisher->poll_query_until('postgres',
 	"SELECT pid != $oldpid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
@@ -552,6 +569,16 @@ $node_publisher->poll_query_until('postgres',
   or die
   "Timed out while waiting for apply to restart after renaming SUBSCRIPTION";
 
+# Check that the expected QUERY STATISTICS message appears,
+# which shows that log_statement_stats=on from the CONNECTION string
+# was correctly passed through to and honored by the walsender.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+like(
+	$logfile,
+	qr/QUERY STATISTICS/,
+	'log_statement_stats in CONNECTION string had effect on publisher\'s walsender'
+);
+
 # check all the cleanup
 $node_subscriber->safe_psql('postgres', "DROP SUBSCRIPTION tap_sub_renamed");
 
-- 
2.51.2