Horton

Re: Vacuum ERRORs out considering freezing dead tuples from before OldestXmin

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Peter Geoghegan <pg@bowt.ie>, Pg Hackers <pgsql-hackers@postgresql.org>, Andres Freund <andres@anarazel.de>, Noah Misch <noah@leadboat.com>
Date: 2025-06-13T14:12:03Z
Lists: pgsql-hackers

Commits

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  1. Test that vacuum removes tuples older than OldestXmin

  2. Lower minimum maintenance_work_mem to 64kB

  3. Add accidentally omitted test to meson build file

  4. Use DELETE instead of UPDATE to speed up vacuum test

  5. Revert "Test that vacuum removes tuples older than OldestXmin"

  6. Ensure vacuum removes all visibly dead tuples older than OldestXmin

On Fri, Jun 13, 2025 at 5:23 AM Melanie Plageman
<melanieplageman@gmail.com> wrote:
> Yep. I have been procrastinating on swapping all this back into my
> brain. I'll start working on it today. I think I just take the
> reverted test and make the UPDATE a DELETE, set mwm 64 kB, make the
> table have 9000 rows and maybe consider using your:
>
> delete from test where ctid::text like '%,2__)';

(Swapping this part back in my brain as well...) I actually don't
think we need that where clause anymore since mwm can be super low
now, and it's a bit mysterious what it was trying to accomplish. Maybe
we can just use the lowest fill factor to reduce WAL -- having a few
dozen pages should push it over the memory limit, regardless of how
many dead tuples are on each pages.

--
John Naylor
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