Re: Add a perl function in Cluster.pm to generate WAL

Hello Tom,

04.01.2024 02:39, Tom Lane wrote:
> Buildfarm member skink has failed 3 times in
> 035_standby_logical_decoding.pl in the last couple of days:
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2024-01-03%2020%3A07%3A15
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2024-01-03%2017%3A09%3A27
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2024-01-01%2020%3A10%3A18
>
> These all look like
>
> # poll_query_until timed out executing this query:
> # select (confl_active_logicalslot = 1) from pg_stat_database_conflicts where datname = 'testdb'
> # expecting this output:
> # t
> # last actual query output:
> # f
>
> although it's notable that two different tests are involved
> (vacuum vs. vacuum full).
>
> I am not real sure what is happening there, but I see that c161ab74f
> changed some details of how that test works, so I wonder if it's
> responsible for these failures.  The timing isn't a perfect match,
> since this commit went in two weeks ago, but I don't see any
> more-recent commits that seem like plausible explanations.

Reproduced here.
As I can see in the failure logs you referenced, the first problem is:
#   Failed test 'inactiveslot slot invalidation is logged with vacuum on pg_authid'
#   at t/035_standby_logical_decoding.pl line 224.

It reminded me of:
https://www.postgresql.org/message-id/b2a1f7d0-7629-72c0-2da7-e9c4e336b010%40gmail.com

It seems that it's not something new, and maybe that my analysis is still
valid. If so, VACUUM FREEZE/autovacuum = off should fix the issue.

Best regards,
Alexander