Quelle  001_concurrent_transaction.pl

# Copyright (c) 2021-2025, PostgreSQL Global Development Group

# Check that a concurrent transaction doesn't cause false negatives in
# pg_check_visible() function
use strict;
use warnings FATAL => 'all';
use PostgreSQL::Test::Cluster;
use PostgreSQL::Test::Utils;
use Test::More;


# Initialize the primary node
my $node = PostgreSQL::Test::Cluster->new('main');
$node->init(allows_streaming => 1);
$node->start;

# Initialize the streaming standby
my $backup_name = 'my_backup';
$node->backup($backup_name);
my $standby = PostgreSQL::Test::Cluster->new('standby');
$standby->init_from_backup($node, $backup_name, has_streaming => 1);
$standby->start;

# Setup another database
$node->safe_psql("postgres", "CREATE DATABASE other_database;\n");
my $bsession = $node->background_psql('other_database');

# Run a concurrent transaction
$bsession->query_safe(
 qq[
 BEGIN;
 SELECT txid_current();
]);

# Create a sample table and run vacuum
$node->safe_psql("postgres",
  "CREATE EXTENSION pg_visibility;\n"
   . "CREATE TABLE vacuum_test AS SELECT 42 i;\n"
   . "VACUUM (disable_page_skipping) vacuum_test;");

# Run pg_check_visible()
my $result = $node->safe_psql("postgres",
 "SELECT * FROM pg_check_visible('vacuum_test');");

# There should be no false negatives
ok($result eq "", "pg_check_visible() detects no errors");

# Run pg_check_visible() on standby
$node->wait_for_catchup($standby);
$result = $standby->safe_psql("postgres",
 "SELECT * FROM pg_check_visible('vacuum_test');");

# There should be no false negatives either
ok($result eq "", "pg_check_visible() detects no errors");

# Shutdown
$bsession->query_safe("COMMIT;");
$bsession->quit;
$node->stop;
$standby->stop;

done_testing();