From: David Steele <david@pgmasters.net>
To: Michael Paquier <michael@paquier.xyz>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Add basic tests for the low-level backup method.
Date: Thu, 14 Mar 2024 09:12:52 +1300
Message-ID: <f20fcc82-dadb-478d-beb4-1e2ffb0ace76@pgmasters.net> (raw)
In-Reply-To: <ZfFEfImMw1gtA9zJ@paquier.xyz>
References: <03e4cf19-fb76-4891-accc-edd429a25b21@pgmasters.net>
<431ecc5d-8c07-4ee1-b05e-3ca536e606bb@pgmasters.net>
<ZeAAPW8h1uxvt4Bj@paquier.xyz>
<4980aba2-9cd4-4bd6-b2e1-e873639ab7ee@pgmasters.net>
<ZfFEfImMw1gtA9zJ@paquier.xyz>
On 3/13/24 19:15, Michael Paquier wrote:
> On Wed, Mar 13, 2024 at 01:12:28PM +1300, David Steele wrote:
>>
>> Not sure what to look for here. There are no distinct messages for crash
>> recovery. Perhaps there should be?
>
> The closest thing I can think of here would be "database system was
> not properly shut down; automatic recovery in progress" as we don't
> have InArchiveRecovery, after checking that the canary is missing. If
> you don't like this suggestion, feel free to say so, of course :)
That works for me. I think I got it confused with "database system was
interrupted..." when I was looking at the success vs. fail logs.
>> Sure, I added a check for the new log message when recovering with a
>> backup_label.
>
> +ok($node_replica->log_contains('completed backup recovery with redo LSN'),
> + 'verify backup recovery performed with backup_label');
>
> Okay for this choice. I was thinking first about "starting backup
> recovery with redo LSN", closer to the area where the backup_label is
> read.
I think you are right that the start message is better since it can only
appear once when the backup_label is found. The completed message could
in theory appear after a restart, though the backup_label must have been
found at some point.
Regards,
-David
Attachments:low-level-backup-test-v3.patch (text/plain, 5.3K) download
From 91f8e8a390713760116990be05d96f8a7e0d1bde Mon Sep 17 00:00:00 2001
From: David Steele <david@pgmasters.net>
Date: Wed, 13 Mar 2024 20:02:40 +0000
Subject: Add basic tests for the low-level backup method.
There are currently no tests for the low-level backup method. pg_backup_start()
and pg_backup_stop() are called but not exercised in any real fashion.
There is a lot more that can be done, but this at least provides some basic
tests and provides a place for future improvement.
---
src/test/recovery/t/042_low_level_backup.pl | 114 ++++++++++++++++++++
1 file changed, 114 insertions(+)
create mode 100644 src/test/recovery/t/042_low_level_backup.pl
diff --git a/src/test/recovery/t/042_low_level_backup.pl b/src/test/recovery/t/042_low_level_backup.plnew file mode 100644index 0000000000..76bac7e324--- /dev/null+++ b/src/test/recovery/t/042_low_level_backup.pl@@ -0,0 +1,114 @@++# Copyright (c) 2023, PostgreSQL Global Development Group++# Test low-level backup method by using pg_backup_start() and pg_backup_stop()+# to create backups.++use strict;+use warnings;++use File::Copy qw(copy);+use File::Path qw(remove_tree);+use PostgreSQL::Test::Cluster;+use PostgreSQL::Test::Utils;+use Test::More;++# Start primary node with archiving+my $node_primary = PostgreSQL::Test::Cluster->new('primary');+$node_primary->init(has_archiving => 1, allows_streaming => 1);+$node_primary->start;++# Start backup+my $backup_name = 'backup1';+my $psql = $node_primary->background_psql('postgres');++$psql->query_safe("SET client_min_messages TO WARNING");+$psql->set_query_timer_restart();+$psql->query_safe("select pg_backup_start('test label')");++# Copy files+my $backup_dir = $node_primary->backup_dir() . '/' . $backup_name;++PostgreSQL::Test::RecursiveCopy::copypath(+ $node_primary->data_dir(), $backup_dir);++# Cleanup some files/paths that should not be in the backup. There is no+# attempt to all the exclusions done by pg_basebackup here, in part because+# they are not required, but also to keep the test simple.+#+# Also remove pg_control because it needs to be copied later and it will be+# obvious if the copy fails.+unlink("$backup_dir/postmaster.pid")+ or BAIL_OUT("unable to unlink $backup_dir/postmaster.pid");+unlink("$backup_dir/postmaster.opts")+ or BAIL_OUT("unable to unlink $backup_dir/postmaster.opts");+unlink("$backup_dir/global/pg_control")+ or BAIL_OUT("unable to unlink $backup_dir/global/pg_control");++remove_tree("$backup_dir/pg_wal", {keep_root => 1})+ or BAIL_OUT("unable to unlink contents of $backup_dir/pg_wal");++# Create a table that will be used to verify that recovery started at the+# correct location, rather than the location recorded in pg_control+$psql->query_safe("create table canary (id int)");++# Advance the checkpoint location in pg_control past the location where the+# backup started. Switch the WAL to make it really obvious that the location+# is different and to put the checkpoint in a new WAL segment.+$psql->query_safe("select pg_switch_wal()");+$psql->query_safe("checkpoint");++# Copy pg_control last so it contains the new checkpoint+copy($node_primary->data_dir() . '/global/pg_control',+ "$backup_dir/global/pg_control")+ or BAIL_OUT("unable to copy global/pg_control");++# Stop backup and get backup_label+my $backup_label = $psql->query_safe("select labelfile from pg_backup_stop()");++# Rather than writing out backup_label, try to recover the backup without+# backup_label to demonstrate that recovery will not work correctly without it,+# i.e. the canary table will be missing and the cluster will be corrupt. Provide+# only the WAL segment that recovery will think it needs.+#+# The point of this test is to explicitly demonstrate that backup_label is+# being used in a later test to get the correct recovery info.+my $node_replica = PostgreSQL::Test::Cluster->new('replica_fail');+$node_replica->init_from_backup($node_primary, $backup_name);+my $canary_query = "select count(*) from pg_class where relname = 'canary'";++copy($node_primary->archive_dir() . '/000000010000000000000003',+ $node_replica->data_dir() . '/pg_wal/000000010000000000000003')+ or BAIL_OUT("unable to copy 000000010000000000000003");++$node_replica->start;++ok($node_replica->safe_psql('postgres', $canary_query) == 0,+ 'canary is missing');++# Check log to ensure crash recovery was used because backup label was missing+ok($node_replica->log_contains(+ 'database system was not properly shut down; automatic recovery in progress'),+ 'verify backup recovery performed with crash recovery');++$node_replica->teardown_node();+$node_replica->clean_node();++# Save backup_label into the backup directory and recover using the primary's+# archive. This time recovery will succeed and the canary table will be+# present.+append_to_file("$backup_dir/backup_label", $backup_label);++$node_replica = PostgreSQL::Test::Cluster->new('replica_success');+$node_replica->init_from_backup($node_primary, $backup_name,+ has_restoring => 1);+$node_replica->start;++ok($node_replica->safe_psql('postgres', $canary_query) == 1,+ 'canary is present');++# Check log to ensure backup_label was used for recovery+ok($node_replica->log_contains('starting backup recovery with redo LSN'),+ 'verify backup recovery performed with backup_label');++done_testing();--
2.34.1
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To: pgsql-hackers@postgresql.org
Cc: david@pgmasters.net, michael@paquier.xyz, pgsql-hackers@lists.postgresql.org
Subject: Re: Add basic tests for the low-level backup method.
In-Reply-To: <f20fcc82-dadb-478d-beb4-1e2ffb0ace76@pgmasters.net>
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