Horton

Re: relfrozenxid may disagree with row XIDs after 1ccc1e05ae

Bowen Shi <zxwsbg12138@gmail.com>

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From: Bowen Shi <zxwsbg12138@gmail.com>
To: Melanie Plageman <melanieplageman@gmail.com>
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>, Andres Freund <andres@anarazel.de>
Date: 2024-05-13T03:19:16Z
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.

Hi,

> Obviously we should actually fix this on back branches, but could we
> at least make the retry loop interruptible in some way so people could
> use pg_cancel/terminate_backend() on a stuck autovacuum worker or
> vacuum process?


If the problem happens in versions <= PG 16, we don't have a good solution
(vacuum process holds the exclusive lock cause checkpoint hangs).

Maybe we can make the retry loop interruptible first. However, since we are
using START_CRIT_SECTION, we cannot simply use CHECK_FOR_INTERRUPTS to
handle it.