Re: relfrozenxid may disagree with row XIDs after 1ccc1e05ae

Peter Geoghegan <pg@bowt.ie>

From: Peter Geoghegan <pg@bowt.ie>

To: Andres Freund <andres@anarazel.de>

Cc: Bowen Shi <zxwsbg12138@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Noah Misch <noah@leadboat.com>, Alexander Lakhin <exclusion@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>

Date: 2024-05-16T16:49:00Z

Lists: pgsql-bugs

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Ensure vacuum removes all visibly dead tuples older than OldestXmin
- 06bf404cd07b 16.4 landed
- 45ce054c02b8 14.13 landed
- dc6354c67017 15.8 landed
Combine freezing and pruning steps in VACUUM
- 6dbb490261a6 17.0 cited
Handle non-chain tuples outside of heap_prune_chain()
- 6f47f6883151 17.0 cited
Fix false reports in pg_visibility
- e85662df44ff 17.0 cited
Remove retry loop in heap_page_prune().
- 1ccc1e05ae8f 17.0 cited
vacuumlazy.c: document vistest and OldestXmin.
- 73f6ec3d3c8d 15.0 cited
Deduplicate choice of horizon for a relation procarray.c.
- d9d8aa9bb9aa 15.0 cited
Remove tupgone special case from vacuumlazy.c.
- 8523492d4e34 14.0 cited
Simplify state managed by VACUUM.
- b4af70cb2103 14.0 cited
Recycle nbtree pages deleted during same VACUUM.
- 9dd963ae2534 14.0 cited
snapshot scalability: Don't compute global horizons while building snapshots.
- dc7420c2c927 14.0 cited
Raise error when affecting tuple moved into different partition.
- f16241bef7cc 11.0 cited

On Thu, May 16, 2024 at 12:38 PM Andres Freund <andres@anarazel.de> wrote:
> I'm wondering if there was index processing, due to the number of tuples. And
> if so, what type of indexes. There'd need to be something that could lead to
> new snapshots being acquired...

Did you ever see this theory of mine, about B-Tree page deletion +
recycling? See:

https://www.postgresql.org/message-id/flat/CAH2-Wz%3DzLcnZO8MqPXQLqOLY%3DCAwQhdvs5Ncg6qMb5nMAam0EA%40mail.gmail.com#d058a6d4b8c8fa7d1ff14349b3a50c3c

(And related nearby emails from me.)

It looked very much like index vacuuming was involved in some way when
I actually had the opportunity to use gdb against an affected
production instance that ran into the problem.

--
Peter Geoghegan