Horton

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

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Melanie Plageman <melanieplageman@gmail.com>, Peter Geoghegan <pg@bowt.ie>, Pg Hackers <pgsql-hackers@postgresql.org>, Noah Misch <noah@leadboat.com>
Date: 2024-06-25T20:41:36Z
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 2024-06-25 14:35:00 -0400, Robert Haas wrote:
> Is there any way that we could instead tweak things so that we adjust
> the visibility test object itself? Like can have a GlobalVisTest API
> where we can supply the OldestXmin from the VacuumCutoffs and have it
> ... do something useful with that?

I doubt that's doable in the back branches. And even on HEAD, I don't think
it's a particularly attractive option - there's just a global vistest for each
of the types of objects with a specific horizon (they need to be updated
occasionally, e.g. when taking snapshots). So there's not really a spot to put
an associated OldestXmin. We could put it there and remove it at the end of
vacuum / in an exception handler, but that seems substantially worse.