Horton

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

Melanie Plageman <melanieplageman@gmail.com>

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From: Melanie Plageman <melanieplageman@gmail.com>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>, Andres Freund <andres@anarazel.de>, Noah Misch <noah@leadboat.com>, Peter Geoghegan <pg@bowt.ie>
Date: 2024-07-08T18:25:16Z
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

Attachments

On Tue, Jul 2, 2024 at 7:07 PM Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> On Mon, Jun 24, 2024 at 4:27 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:
> >
> > Would it be possible to make it robust so that we could always run it
> > with "make check"? This seems like an important corner case to
> > regression test.
>
> Okay, I've attached a new version of the patch and a new version of
> the repro that may be fast and stable enough to commit. It is more
> minimal than the previous version. I made the table as small as I
> could to still trigger two rounds of index vacuuming. I tried to make
> it as stable as possible. I also removed the cursor on the standby
> that could trigger recovery conflicts. It would be super helpful if
> someone could take a look at the test and point out any ways I could
> make it even more likely to be stable.

Attached v3 has one important additional component in the test -- I
use pg_stat_progress_vacuum to confirm that we actually do more than
one pass of index vacuuming. Otherwise, it would have been trivial for
the test to incorrectly pass.

I could still use another pair of eyes on the test (looking out for
stability enhancing measures I could take). I also would be happy if
someone looked at the commit message and/or comments to let me know if
they make sense.

I'll finish with versions of the patch and test targeted at v14-16 and
propose those before committing this.

- Melanie