mirror of https://github.com/postgres/postgres
When a standby is promoted, CleanupAfterArchiveRecovery() may decide to rename the final WAL file from the old timeline by adding ".partial" to the name. If WAL summarization is enabled and this file is renamed before its partial contents are summarized, WAL summarization breaks: the summarizer gets stuck at that point in the WAL stream and just errors out. To fix that, first make the startup process wait for WAL summarization to catch up before renaming the file. Generally, this should be quick, and if it's not, the user can shut off summarize_wal and try again. To make this fix work, also teach the WAL summarizer that after a promotion has occurred, no more WAL can appear on the previous timeline: previously, the WAL summarizer wouldn't switch to the new timeline until we actually started writing WAL there, but that meant that when the startup process was waiting for the WAL summarizer, it was waiting for an action that the summarizer wasn't yet prepared to take. In the process of fixing these bugs, I realized that the logic to wait for WAL summarization to catch up was spread out in a way that made it difficult to reuse properly, so this code refactors things to make it easier. Finally, add a test case that would have caught this bug and the previously-fixed bug that WAL summarization sometimes needs to back up when the timeline changes. Discussion: https://postgr.es/m/CA+TgmoZGEsZodXC4f=XZNkAeyuDmWTSkpkjCEOcF19Am0mt_OA@mail.gmail.compull/183/head
Robert Haas
1 year ago
parent
f2af1f4559
commit
53b327f83e
@ -0,0 +1,81 @@ |
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# Copyright (c) 2021-2024, PostgreSQL Global Development Group |
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# |
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# Test whether WAL summaries are complete such that incremental backup |
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# can be performed after promoting a standby at an arbitrary LSN. |
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|
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use strict; |
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use warnings FATAL => 'all'; |
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use File::Compare; |
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use PostgreSQL::Test::Cluster; |
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use PostgreSQL::Test::Utils; |
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use Test::More; |
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# Can be changed to test the other modes. |
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my $mode = $ENV{PG_TEST_PG_COMBINEBACKUP_MODE} || '--copy'; |
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note "testing using mode $mode"; |
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|
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# Set up a new database instance. |
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my $node1 = PostgreSQL::Test::Cluster->new('node1'); |
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$node1->init(has_archiving => 1, allows_streaming => 1); |
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$node1->append_conf('postgresql.conf', 'summarize_wal = on'); |
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$node1->append_conf('postgresql.conf', 'log_min_messages = debug1'); |
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$node1->start; |
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|
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# Create a table and insert a test row into it. |
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$node1->safe_psql('postgres', <<EOM); |
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CREATE TABLE mytable (a int, b text); |
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INSERT INTO mytable VALUES (1, 'avocado'); |
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EOM |
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|
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# Take a full backup. |
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my $backup1path = $node1->backup_dir . '/backup1'; |
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$node1->command_ok( |
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[ 'pg_basebackup', '-D', $backup1path, '--no-sync', '-cfast' ], |
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"full backup from node1"); |
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|
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# Checkpoint and record LSN after. |
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$node1->safe_psql('postgres', 'CHECKPOINT'); |
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my $lsn = $node1->safe_psql('postgres', 'SELECT pg_current_wal_insert_lsn()'); |
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|
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# Insert a second row on the original node. |
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$node1->safe_psql('postgres', <<EOM); |
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INSERT INTO mytable VALUES (2, 'beetle'); |
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EOM |
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|
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# Now create a second node. We want this to stream from the first node and |
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# then stop recovery at some arbitrary LSN, not just when it hits the end of |
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# WAL, so use a recovery target. |
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my $node2 = PostgreSQL::Test::Cluster->new('node2'); |
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$node2->init_from_backup($node1, 'backup1', 'has_streaming' => 1); |
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$node2->append_conf('postgresql.conf', <<EOM); |
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recovery_target_lsn = '$lsn' |
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recovery_target_action = 'pause' |
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EOM |
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$node2->start(); |
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# Wait until recoveery pauses, then promote. |
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$node2->poll_query_until('postgres', "SELECT pg_get_wal_replay_pause_state() = 'paused';"); |
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$node2->safe_psql('postgres', "SELECT pg_promote()"); |
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|
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# Once promotion occurs, insert a second row on the new node. |
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$node2->poll_query_until('postgres', "SELECT pg_is_in_recovery() = 'f';"); |
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$node2->safe_psql('postgres', <<EOM); |
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INSERT INTO mytable VALUES (2, 'blackberry'); |
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EOM |
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# Now take an incremental backup. If WAL summarization didn't follow the |
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# timeline cange correctly, something should break at this point. |
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my $backup2path = $node1->backup_dir . '/backup2'; |
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$node2->command_ok( |
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[ 'pg_basebackup', '-D', $backup2path, '--no-sync', '-cfast', |
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'--incremental', $backup1path . '/backup_manifest' ], |
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"incremental backup from node2"); |
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# Restore the incremental backup and use it to create a new node. |
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my $node3 = PostgreSQL::Test::Cluster->new('node3'); |
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$node3->init_from_backup($node1, 'backup2', |
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combine_with_prior => [ 'backup1' ]); |
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$node3->start(); |
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done_testing(); |
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