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# Copyright (c) 2021-2025, PostgreSQL Global Development Group
# Test replication statistics data in pg_stat_replication_slots is sane after
# drop replication slot and restart.
use strict;
use warnings FATAL => 'all';
use File::Path qw(rmtree);
use PostgreSQL::Test::Cluster;
use PostgreSQL::Test::Utils;
use Test::More;
# Test set-up
my $node = PostgreSQL::Test::Cluster->new('test');
$node->init(allows_streaming => 'logical');
$node->append_conf('postgresql.conf', 'synchronous_commit = on');
$node->start;
# Check that replication slot stats are expected.
sub test_slot_stats
{
local $Test::Builder::Level = $Test::Builder::Level + 1;
my ($node, $expected, $msg) = @_;
my $result = $node->safe_psql(
'postgres', qq[
SELECT slot_name, total_txns > 0 AS total_txn,
total_bytes > 0 AS total_bytes
FROM pg_stat_replication_slots
ORDER BY slot_name]);
is($result, $expected, $msg);
}
# Create table.
$node->safe_psql('postgres', "CREATE TABLE test_repl_stat(col1 int)");
# Create replication slots.
$node->safe_psql(
'postgres', qq[
SELECT pg_create_logical_replication_slot('regression_slot1', 'test_decoding');
SELECT pg_create_logical_replication_slot('regression_slot2', 'test_decoding');
SELECT pg_create_logical_replication_slot('regression_slot3', 'test_decoding');
SELECT pg_create_logical_replication_slot('regression_slot4', 'test_decoding');
]);
# Insert some data.
$node->safe_psql('postgres',
"INSERT INTO test_repl_stat values(generate_series(1, 5));");
$node->safe_psql(
'postgres', qq[
SELECT data FROM pg_logical_slot_get_changes('regression_slot1', NULL,
NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot2', NULL,
NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot3', NULL,
NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot4', NULL,
NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
]);
# Wait for the statistics to be updated.
$node->poll_query_until(
'postgres', qq[
SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
WHERE slot_name ~ 'regression_slot'
AND total_txns > 0 AND total_bytes > 0;
]) or die "Timed out while waiting for statistics to be updated";
# Test to drop one of the replication slot and verify replication statistics data is
# fine after restart.
$node->safe_psql('postgres',
"SELECT pg_drop_replication_slot('regression_slot4')");
$node->stop;
$node->start;
# Verify statistics data present in pg_stat_replication_slots are sane after
# restart.
test_slot_stats(
$node,
qq(regression_slot1|t|t
regression_slot2|t|t
regression_slot3|t|t),
'check replication statistics are updated');
# Test to remove one of the replication slots and adjust
# max_replication_slots accordingly to the number of slots. This leads
# to a mismatch between the number of slots present in the stats file and the
# number of stats present in shared memory. We verify
# replication statistics data is fine after restart.
$node->stop;
my $datadir = $node->data_dir;
my $slot3_replslotdir = "$datadir/pg_replslot/regression_slot3";
rmtree($slot3_replslotdir);
$node->append_conf('postgresql.conf', 'max_replication_slots = 2');
$node->start;
# Verify statistics data present in pg_stat_replication_slots are sane after
# restart.
test_slot_stats(
$node,
qq(regression_slot1|t|t
regression_slot2|t|t),
'check replication statistics after removing the slot file');
# cleanup
$node->safe_psql('postgres', "DROP TABLE test_repl_stat");
$node->safe_psql('postgres',
"SELECT pg_drop_replication_slot('regression_slot1')");
$node->safe_psql('postgres',
"SELECT pg_drop_replication_slot('regression_slot2')");
# shutdown
$node->stop;
# Test replication slot stats persistence in a single session. The slot
# is dropped and created concurrently of a session peeking at its data
# repeatedly, hence holding in its local cache a reference to the stats.
$node->start;
my $slot_name_restart = 'regression_slot5';
$node->safe_psql('postgres',
"SELECT pg_create_logical_replication_slot('$slot_name_restart', 'test_decoding');"
);
# Look at slot data, with a persistent connection.
my $bpgsql = $node->background_psql('postgres', on_error_stop => 1);
# Launch query and look at slot data, incrementing the refcount of the
# stats entry.
$bpgsql->query_safe(
"SELECT pg_logical_slot_peek_binary_changes('$slot_name_restart', NULL, NULL)"
);
# Drop the slot entry. The stats entry is not dropped yet as the previous
# session still holds a reference to it.
$node->safe_psql('postgres',
"SELECT pg_drop_replication_slot('$slot_name_restart')");
# Create again the same slot. The stats entry is reinitialized, not marked
# as dropped anymore.
$node->safe_psql('postgres',
"SELECT pg_create_logical_replication_slot('$slot_name_restart', 'test_decoding');"
);
# Look again at the slot data. The local stats reference should be refreshed
# to the reinitialized entry.
$bpgsql->query_safe(
"SELECT pg_logical_slot_peek_binary_changes('$slot_name_restart', NULL, NULL)"
);
# Drop again the slot, the entry is not dropped yet as the previous session
# still has a refcount on it.
$node->safe_psql('postgres',
"SELECT pg_drop_replication_slot('$slot_name_restart')");
# Shutdown the node, which should happen cleanly with the stats file written
# to disk. Note that the background session created previously needs to be
# hold *while* the node is shutting down to check that it drops the stats
# entry of the slot before writing the stats file.
$node->stop;
# Make sure that the node is correctly shut down. Checking the control file
# is not enough, as the node may detect that something is incorrect after the
# control file has been updated and the shutdown checkpoint is finished, so
# also check that the stats file has been written out.
command_like(
[ 'pg_controldata', $node->data_dir ],
qr/Database cluster state:\s+shut down\n/,
'node shut down ok');
my $stats_file = "$datadir/pg_stat/pgstat.stat";
ok(-f "$stats_file", "stats file must exist after shutdown");
$bpgsql->quit;
done_testing();
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