Date: Thu, 21 Nov 2019 14:32:37 +0100
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: =?utf-8?Q?Ond=C5=99ej?= Jirman <megi@xff.cz>
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #16129: Segfault in tts_virtual_materialize in logical
 replication worker
Message-ID: <20191121133237.vgxoilemblaqmstu@development>
References: <16129-a0c0f48e71741e5f@postgresql.org>
 <20191121103940.gpadc7xmssl63sad@development>
 <20191121115326.arierrbeok6we5sv@core.my.home>
 <20191121125913.4dhhwpbw67vqx37o@core.my.home>
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On Thu, Nov 21, 2019 at 01:59:13PM +0100, Ondřej Jirman wrote:
>On Thu, Nov 21, 2019 at 12:53:26PM +0100, postgresql wrote:
>> Hello,
>>
>> On Thu, Nov 21, 2019 at 11:39:40AM +0100, Tomas Vondra wrote:
>> > On Thu, Nov 21, 2019 at 01:14:18AM +0000, PG Bug reporting form wrote:
>> > > Replication of one of my databases (running on ARMv7 machine) started
>> > > segfaulting on the subscriber side (x86_64) like this:
>> > >
>> > > #0  0x00007fc259739917 in __memmove_sse2_unaligned_erms () from
>> > > /usr/lib/libc.so.6
>> > > #1  0x000055d033e93d44 in memcpy (__len=620701425, __src=<optimized out>,
>> > > __dest=0x55d0356da804) at /usr/include/bits/string_fortified.h:34
>> > > #2  tts_virtual_materialize (slot=0x55d0356da3b8) at execTuples.c:235
>> > > #3  0x000055d033e94d32 in ExecFetchSlotHeapTuple
>> > > (slot=slot@entry=0x55d0356da3b8, materialize=materialize@entry=true,
>> > > shouldFree=shouldFree@entry=0x7fff0e7cf387) at execTuples.c:1624
>>
>> I forgot to add that publisher is still PostgreSQL 11.5.
>>
>
>I can also add that I have data checksumming enabled on both ends, and
>it did not detect any corruption:
>
># pg_verify_checksums -D /var/lib/postgres/data
>Checksum scan completed
>Data checksum version: 1
>Files scanned:  1751
>Blocks scanned: 86592
>Bad checksums:  0
>
># pg_checksums /var/lib/postgres/data
>Checksum operation completed
>Files scanned:  22777
>Blocks scanned: 3601527
>Bad checksums:  0
>Data checksum version: 1
>
>WAL log on the publisher is also dumpable to a state hours after the issues
>started:
>
>I've put the dump here, if it's of any use: https://megous.com/dl/tmp/wal_dump.txt
>
>Dump ends with:
>
>pg_waldump: FATAL:  error in WAL record at 2/BBE0E538: invalid record length at 2/BBE0E5A8: wanted 24, got 0
>
>But that seems normal. I get that error on my other database clusters, too.
>
>I managed to extract the failing logical decoding data from the publisher, if
>that helps:
>
>
>SELECT * FROM pg_logical_slot_peek_binary_changes('l5_hometv', NULL, NULL, 'proto_version', '1', 'publication_names', 'pub');
>
> 2/BBD86EA0 | 56395 | \x4200000002bbd880b800023acd790ce5510000dc4b
> 2/BBD87E90 | 56395 | \x5200004a687075626c696300766964656f73006400080169640000000017ffffffff007469746c650000000019ffffffff00636f7665725f696d6167650000000011ffffffff006d657461646174610000000edafffffff
>f0063617465676f72790000000017ffffffff007075626c6973686564000000043affffffff006164646564000000045affffffff00706c617965640000000010ffffffff
> 2/BBD87E90 | 56395 | \x5500004a684e0008740000000438333933740000005650617a6465726b613a204f206dc3a964696120736520706f7665646520626f6a2e204b64796279206ec3a17320706f6c6974696369206d696c6f76616c692c20627
>96c6f206279206ec49b636f20c5a17061746ec49b7574000001397b226964223a20226430313064343430303965323131656162323539616331663662323230656538222c202264617465223a2022323031392d31312d3138222c20226e616d65223a20
>2250617a6465726b613a204f206dc3a964696120736520706f7665646520626f6a2e204b64796279206ec3a17320706f6c6974696369206d696c6f76616c692c2062796c6f206279206ec49b636f20c5a17061746ec49b222c2022696d616765223a202
>268747470733a2f2f63646e2e7873642e637a2f726573697a652f63353535656239633131353333313632386164666539396237343534353731655f657874726163743d302c302c313931392c313038305f726573697a653d3732302c3430355f2e6a70
>673f686173683d6362316362623836336230353361613561333761346666616439303865303431227d7400000003323432740000000a323031392d31312d3138740000001a323031392d31312d31382031323a35303a30312e383136333736740000000
>174
> 2/BBD880E8 | 56395 | \x430000000002bbd880b800000002bbd880e800023acd790ce551
>

Can you show the whole transaction? From the WAL dump it seems it just
did a single UPDATE:

rmgr: Heap        len (rec/tot):     59/  4075, tx:      56395, lsn: 2/BBD86EA0, prev 2/BBD86E68, desc: LOCK off 2: xid 56395: flags 0 LOCK_ONLY EXCL_LOCK
	blkref #0: rel 1663/19030/19048 fork main blk 415 (FPW); hole: offset: 56, length: 4176
rmgr: Heap        len (rec/tot):    523/   523, tx:      56395, lsn: 2/BBD87E90, prev 2/BBD86EA0, desc: HOT_UPDATE off 2 xmax 56395 ; new off 9 xmax 0
	blkref #0: rel 1663/19030/19048 fork main blk 415
rmgr: Transaction len (rec/tot):     46/    46, tx:      56395, lsn: 2/BBD880B8, prev 2/BBD87E90, desc: COMMIT 2019-11-20 23:28:47.016273 CET

Which fields does it update?

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services