1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
# Copyright (c) 2021, PostgreSQL Global Development Group
# Tests for already-propagated WAL segments ending in incomplete WAL records.
use strict;
use warnings;
use FindBin;
use PostgresNode;
use TestLib;
use Test::More;
plan tests => 3;
# Test: Create a physical replica that's missing the last WAL file,
# then restart the primary to create a divergent WAL file and observe
# that the replica replays the "overwrite contrecord" from that new
# file and the standby promotes successfully.
my $node = PostgresNode->get_new_node('primary');
$node->init(allows_streaming => 1);
# We need these settings for stability of WAL behavior.
$node->append_conf(
'postgresql.conf', qq(
autovacuum = off
wal_keep_segments = 16
));
$node->start;
$node->safe_psql('postgres', 'create table filler (a int, b text)');
# Now consume all remaining room in the current WAL segment, leaving
# space enough only for the start of a largish record.
$node->safe_psql(
'postgres', q{
DO $$
DECLARE
wal_segsize int := setting::int FROM pg_settings WHERE name = 'wal_segment_size';
remain int;
iters int := 0;
BEGIN
LOOP
INSERT into filler
select g, repeat(md5(g::text), (random() * 60 + 1)::int)
from generate_series(1, 10) g;
remain := wal_segsize - (pg_current_wal_insert_lsn() - '0/0') % wal_segsize;
IF remain < 2 * setting::int from pg_settings where name = 'block_size' THEN
RAISE log 'exiting after % iterations, % bytes to end of WAL segment', iters, remain;
EXIT;
END IF;
iters := iters + 1;
END LOOP;
END
$$;
});
my $initfile = $node->safe_psql('postgres',
'SELECT pg_walfile_name(pg_current_wal_insert_lsn())');
$node->safe_psql('postgres',
qq{SELECT pg_logical_emit_message(true, 'test 026', repeat('xyzxz', 123456))}
);
#$node->safe_psql('postgres', qq{create table foo ()});
my $endfile = $node->safe_psql('postgres',
'SELECT pg_walfile_name(pg_current_wal_insert_lsn())');
ok($initfile ne $endfile, "$initfile differs from $endfile");
# Now stop abruptly, to avoid a stop checkpoint. We can remove the tail file
# afterwards, and on startup the large message should be overwritten with new
# contents
$node->stop('immediate');
unlink $node->basedir . "/pgdata/pg_wal/$endfile"
or die "could not unlink " . $node->basedir . "/pgdata/pg_wal/$endfile: $!";
# OK, create a standby at this spot.
$node->backup_fs_cold('backup');
my $node_standby = PostgresNode->get_new_node('standby');
$node_standby->init_from_backup($node, 'backup', has_streaming => 1);
$node_standby->start;
$node->start;
$node->safe_psql('postgres',
qq{create table foo (a text); insert into foo values ('hello')});
$node->safe_psql('postgres',
qq{SELECT pg_logical_emit_message(true, 'test 026', 'AABBCC')});
my $until_lsn = $node->safe_psql('postgres', "SELECT pg_current_wal_lsn()");
my $caughtup_query =
"SELECT '$until_lsn'::pg_lsn <= pg_last_wal_replay_lsn()";
$node_standby->poll_query_until('postgres', $caughtup_query)
or die "Timed out while waiting for standby to catch up";
ok($node_standby->safe_psql('postgres', 'select * from foo') eq 'hello',
'standby replays past overwritten contrecord');
# Verify message appears in standby's log
my $log = slurp_file($node_standby->logfile);
like(
$log,
qr[successfully skipped missing contrecord at],
"found log line in standby");
# Verify promotion is successful
$node_standby->promote;
$node->stop;
$node_standby->stop;
|
