Add a tap test to verify the management of the new replication slot

Author: Zhijie Hou

src/test/subscription/t/035_conflicts.pl

@@ -1,6 +1,6 @@
 # Copyright (c) 2025, PostgreSQL Global Development Group
 
-# Test the conflict detection of conflict type 'multiple_unique_conflicts'.
+# Test conflicts in logical replication
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
@@ -18,7 +18,7 @@
 
 # Create a subscriber node
 my $node_subscriber = PostgreSQL::Test::Cluster->new('subscriber');
-$node_subscriber->init;
+$node_subscriber->init(allows_streaming => 'logical');
 $node_subscriber->start;
 
 # Create a table on publisher
@@ -145,4 +145,152 @@
 
 pass('multiple_unique_conflicts detected on a leaf partition during insert');
 
+###############################################################################
+# Setup a bidirectional logical replication between node_A & node_B
+###############################################################################
+
+# Initialize nodes.
+
+# node_A. Increase the log_min_messages setting to DEBUG2 to debug test
+# failures. Disable autovacuum to avoid generating xid that could affect the
+# replication slot's xmin value.
+my $node_A = $node_publisher;
+$node_A->append_conf(
+	'postgresql.conf',
+	qq{autovacuum = off
+	log_min_messages = 'debug2'});
+$node_A->restart;
+
+# node_B
+my $node_B = $node_subscriber;
+$node_B->append_conf('postgresql.conf', "track_commit_timestamp = on");
+$node_B->restart;
+
+# Create table on node_A
+$node_A->safe_psql('postgres', "CREATE TABLE tab (a int PRIMARY KEY, b int)");
+
+# Create the same table on node_B
+$node_B->safe_psql('postgres', "CREATE TABLE tab (a int PRIMARY KEY, b int)");
+
+my $subname_AB = 'tap_sub_a_b';
+my $subname_BA = 'tap_sub_b_a';
+
+# Setup logical replication
+# node_A (pub) -> node_B (sub)
+my $node_A_connstr = $node_A->connstr . ' dbname=postgres';
+$node_A->safe_psql('postgres', "CREATE PUBLICATION tap_pub_A FOR TABLE tab");
+$node_B->safe_psql(
+	'postgres', "
+	CREATE SUBSCRIPTION $subname_BA
+	CONNECTION '$node_A_connstr application_name=$subname_BA'
+	PUBLICATION tap_pub_A
+	WITH (origin = none, retain_conflict_info = true)");
+
+# node_B (pub) -> node_A (sub)
+my $node_B_connstr = $node_B->connstr . ' dbname=postgres';
+$node_B->safe_psql('postgres', "CREATE PUBLICATION tap_pub_B FOR TABLE tab");
+$node_A->safe_psql(
+	'postgres', "
+	CREATE SUBSCRIPTION $subname_AB
+	CONNECTION '$node_B_connstr application_name=$subname_AB'
+	PUBLICATION tap_pub_B
+	WITH (origin = none, copy_data = off, retain_conflict_info = true)");
+
+# Wait for initial table sync to finish
+$node_A->wait_for_subscription_sync($node_B, $subname_AB);
+$node_B->wait_for_subscription_sync($node_A, $subname_BA);
+
+is(1, 1, 'Bidirectional replication setup is complete');
+
+# Confirm that the additional replication slot is created on both nodes and the
+# xmin value is valid.
+
+ok( $node_A->poll_query_until(
+		'postgres',
+		"SELECT xmin IS NOT NULL from pg_replication_slots WHERE slot_name = 'pg_conflict_detection'"
+	),
+	"the xmin value of slot 'pg_conflict_detection' is valid on Node A");
+
+ok( $node_B->poll_query_until(
+		'postgres',
+		"SELECT xmin IS NOT NULL from pg_replication_slots WHERE slot_name = 'pg_conflict_detection'"
+	),
+	"the xmin value of slot 'pg_conflict_detection' is valid on Node B");
+
+my $result = $node_A->safe_psql('postgres',
+	"SELECT retain_conflict_info FROM pg_stat_subscription WHERE subname='$subname_AB';");
+is($result, qq(t), 'worker on node A retains conflict information');
+$result = $node_B->safe_psql('postgres',
+	"SELECT retain_conflict_info FROM pg_stat_subscription WHERE subname='$subname_BA';");
+is($result, qq(t), 'worker on node B retains conflict information');
+
+###############################################################################
+# Check that dead tuples on node A cannot be cleaned by VACUUM until the
+# concurrent transactions on Node B have been applied and flushed on Node A.
+###############################################################################
+
+# Insert a record
+$node_A->safe_psql('postgres', "INSERT INTO tab VALUES (1, 1), (2, 2);");
+$node_A->wait_for_catchup($subname_BA);
+
+$result = $node_B->safe_psql('postgres', "SELECT * FROM tab;");
+is($result, qq(1|1
+2|2), 'check replicated insert on node B');
+
+# Disable the logical replication from node B to node A
+$node_A->safe_psql('postgres', "ALTER SUBSCRIPTION $subname_AB DISABLE");
+
+my $log_location = -s $node_B->logfile;
+
+$node_B->safe_psql('postgres', "UPDATE tab SET b = 3 WHERE a = 1;");
+$node_A->safe_psql('postgres', "DELETE FROM tab WHERE a = 1;");
+
+$node_A->wait_for_catchup($subname_BA);
+
+my ($cmdret, $stdout, $stderr) = $node_A->psql(
+	'postgres', qq(VACUUM (verbose) public.tab;)
+);
+
+ok( $stderr =~
+	  qr/1 are dead but not yet removable/,
+	'the deleted column is non-removable');
+
+$node_A->safe_psql(
+	'postgres', "ALTER SUBSCRIPTION $subname_AB ENABLE;");
+$node_B->wait_for_catchup($subname_AB);
+
+# Remember the next transaction ID to be assigned
+my $next_xid = $node_A->safe_psql('postgres', "SELECT txid_current() + 1;");
+
+# Confirm that the xmin value is updated
+ok( $node_A->poll_query_until(
+		'postgres',
+		"SELECT xmin = $next_xid from pg_replication_slots WHERE slot_name = 'pg_conflict_detection'"
+	),
+	"the xmin value of slot 'pg_conflict_detection' is updated on Node A");
+
+###############################################################################
+# Check that the replication slot pg_conflict_detection is dropped after
+# removing all the subscriptions.
+###############################################################################
+
+$node_B->safe_psql(
+	'postgres', "DROP SUBSCRIPTION $subname_BA");
+
+ok( $node_B->poll_query_until(
+		'postgres',
+		"SELECT count(*) = 0 FROM pg_replication_slots WHERE slot_name = 'pg_conflict_detection'"
+	),
+	"the slot 'pg_conflict_detection' has been dropped on Node B");
+
+$node_A->safe_psql(
+	'postgres', "DROP SUBSCRIPTION $subname_AB");
+
+ok( $node_A->poll_query_until(
+		'postgres',
+		"SELECT count(*) = 0 FROM pg_replication_slots WHERE slot_name = 'pg_conflict_detection'"
+	),
+	"the slot 'pg_conflict_detection' has been dropped on Node A");
+
+
 done_testing();