Horton

Re: relfrozenxid may disagree with row XIDs after 1ccc1e05ae

Melanie Plageman <melanieplageman@gmail.com>

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From: Melanie Plageman <melanieplageman@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Noah Misch <noah@leadboat.com>, Peter Geoghegan <pg@bowt.ie>, Alexander Lakhin <exclusion@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Date: 2024-05-16T23:57:27Z
Lists: pgsql-bugs

Commits

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

  2. Combine freezing and pruning steps in VACUUM

  3. Handle non-chain tuples outside of heap_prune_chain()

  4. Fix false reports in pg_visibility

  5. Remove retry loop in heap_page_prune().

  6. vacuumlazy.c: document vistest and OldestXmin.

  7. Deduplicate choice of horizon for a relation procarray.c.

  8. Remove tupgone special case from vacuumlazy.c.

  9. Simplify state managed by VACUUM.

  10. Recycle nbtree pages deleted during same VACUUM.

  11. snapshot scalability: Don't compute global horizons while building snapshots.

  12. Raise error when affecting tuple moved into different partition.

Attachments

On Thu, May 9, 2024 at 5:56 PM Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> I can repro the hang on 14 and 15 with the following:

-- snip --

I finally managed to write a TAP test which does the same thing as my
repro. The attached patch contains a test that is meant purely for
demonstration and reproduction by others -- not as a suggestion to add
to the recovery test suite on an ongoing basis.

I also attached the fix (targeting REL_15_STABLE) so that you can try
the repro TAP test with and without the fix.

The test is a bit fragile, so I won't be surprised if it doesn't work
for everyone.

Thank you so much to Andres, Thomas, and Daniel, all of whom helped me
debug various issues I was having with trying to make background_psql
work reliably for this test on 15. This was truly painful, but I never
would have gotten through it without my IPC::Run support group.

I'll probably add more robust comments to the test next week in
preparation for writing a detailed commit message for the fix
explaining the scenario.

- Melanie