Re: Slot's restart_lsn may point to removed WAL segment after hard restart unexpectedly

Hi, Alexander!

On Sun, Jun 15, 2025 at 12:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:
>
> Hello Alexander,
>
> 10.06.2025 23:14, Alexander Korotkov wrote:
>
> So, my proposal is to commit the attached patchset to the HEAD, and
> commit [1] to the back branches.  Any objections?
>
>
> As the buildfarm animal prion shows [1], the 046_checkpoint_logical_slot
> test fails with "-DRELCACHE_FORCE_RELEASE -DCATCACHE_FORCE_RELEASE":
> # poll_query_until timed out executing this query:
> #
> #         SELECT count(*) > 0 FROM pg_stat_activity
> #         WHERE backend_type = 'client backend' AND wait_event = 'logical-replication-slot-advance-segment'
> #
> # expecting this output:
> # t
> # last actual query output:
> # f
> # with stderr:
> [04:16:27] t/046_checkpoint_logical_slot.pl ......
> Dubious, test returned 29 (wstat 7424, 0x1d00)
> No subtests run
> [04:20:58] t/047_checkpoint_physical_slot.pl ..... ok   271294 ms ( 0.00 usr  0.00 sys +  0.37 cusr  0.26 csys =
0.63CPU) 
>
> I'm able to reproduce this locally as well. Though the test passes for me
> with the increased timeout, that is it's not stuck:
> PG_TEST_TIMEOUT_DEFAULT=360 PROVE_TESTS="t/046*" make -s check -C src/test/recovery/
> # +++ tap check in src/test/recovery +++
> t/046_checkpoint_logical_slot.pl .. ok
> All tests successful.
> Files=1, Tests=1, 533 wallclock secs ( 0.01 usr  0.00 sys +  4.70 cusr  9.61 csys = 14.32 CPU)
> Result: PASS
>
> Could you have a look?
>
> [1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=prion&dt=2025-06-14%2001%3A58%3A06

Hmm... It seems to take too long to advance the segment with these
options on.  Sure, I'll check this!

------
Regards,
Alexander Korotkov
Supabase