Horton

RE: pg_logical_slot_get_changes waits continously for a partial WAL record spanning across 2 pages

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Michael Paquier' <michael@paquier.xyz>, vignesh C <vignesh21@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Alexander Korotkov <aekorotkov@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Amit Kapila <amit.kapila16@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>
Date: 2025-07-15T09:14:27Z
Lists: pgsql-hackers 
Dear Michael,

> I like the addition of an extra pg_logical_emit_message() in test 046
> anyway, down to v17, in the test 046 for all the branches.  Even if
> the reproduction is sporadic, we have seen it pretty quickly in the CI
> and in the buildfarm so it would not go unnoticed for a long time if
> we mess up with this stuff again.

I put pg_logical_emit_message() after injection_points_wakeup(), but your patch
puts it before. I verified even your patch can reproduce the issue, but is there
a reason?
(This is not a comment which must be fixed, I just want to know the reason to study)

> With all that said, I'll move on with this stuff once the embargo for
> v18 beta2 is lifted and the tag is pushed.  That should happen in 24h
> or so, I guess.

The provided patches looks good to me.

Best regards,
Hayato Kuroda
FUJITSU LIMITED

Commits

  1. Fix infinite wait when reading a partially written WAL record

  2. Improve the stability of the recovery test 047_checkpoint_physical_slot

  3. Improve recovery test 046_checkpoint_logical_slot