Re: pgsql: xlog.c: Remove global variables ReadRecPtr and EndRecPtr.

On Wed, Nov 24, 2021 at 11:28 AM Robert Haas <rhaas(at)postgresql(dot)org> wrote:
> xlog.c: Remove global variables ReadRecPtr and EndRecPtr.
> https://git.postgresql.org/pg/commitdiff/d2ddfa681db27a138acb63c8defa8cc6fa588922

There is a buildfarm failure on lapwing which looks likely to be
attributable to this commit, but I don't understand what has gone
wrong exactly. The error message that is reported is:

[17:07:19] t/025_stuck_on_old_timeline.pl ....... ok 6048 ms
# poll_query_until timed out executing this query:
# SELECT '0/201E8E0'::pg_lsn <= pg_last_wal_replay_lsn()
# expecting this output:
# t
# last actual query output:
#
# with stderr:
# psql: error: connection to server on socket
"/tmp/SrZekgRh7K/.s.PGSQL.57959" failed: No such file or directory
# Is the server running locally and accepting connections on that socket?

This output confused me for a while because I thought the failure was
in test 025, but I should have realized that the problem must be in
026, since 025 finished with "ok". Anyway, in
026_overwrite_contrecord_standby.log there's this:

2021-11-24 17:07:41.388 UTC [1473:1] LOG: started streaming WAL from
primary at 0/2000000 on timeline 1
2021-11-24 17:07:41.428 UTC [1449:6] FATAL: mismatching overwritten
LSN 0/1FFE014 -> 0/1FFE000
2021-11-24 17:07:41.428 UTC [1449:7] CONTEXT: WAL redo at 0/2000024
for XLOG/OVERWRITE_CONTRECORD: lsn 0/1FFE014; time 2021-11-24
17:07:41.127049+00

Beyond the fact that something bad has happened, I'm not sure what
that is trying to tell me.

--
Robert Haas
EDB: http://www.enterprisedb.com