Horton

Re: BUG #17255: Server crashes in index_delete_sort_cmp() due to race condition with vacuum

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: pgsql-bugs@lists.postgresql.org, Peter Geoghegan <pg@bowt.ie>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>, Alexander Lakhin <exclusion@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>, Mark Dilger <mark.dilger@enterprisedb.com>
Date: 2021-11-19T18:55:41Z
Lists: pgsql-bugs 
Hi, 

On November 18, 2021 6:55:08 PM PST, Peter Geoghegan <pg@bowt.ie> wrote:
>On Thu, Nov 18, 2021 at 4:36 PM Andres Freund <andres@anarazel.de> wrote:
>> Attached is such an isolationtest. In an unmodified HEAD it ends up with
>
>> without amcheck detecting corruption at that point:(.
>
>The best way to teach amcheck to detect this kind of thing is bound to
>be verification of HOT chains themselves:
>
>https://www.postgresql.org/message-id/flat/CAH2-Wznphpd490o%2Bur_bi6-YmC47hRu3Qyxod72RLqC-Uvuhcg%40mail.gmail.com

That'd not reliably catch this kind of thing, because the hot chains easily can end up correct enough looking.


>It would also be nice to teach verify_nbtree.c to look out for the
>presence of index tuples that shouldn't be there during heapallindexed
>verification, but that's significantly harder.

I think what we really need is a pass that verifies that heap tuples reached via the index actually match the index key. There's just too many things that can break that. It'll not be blazingly fast, but there's just way too many things that other approaches just won't find.

Andres

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Commits

  1. vacuumlazy.c: Standardize rel_pages terminology.

  2. vacuumlazy.c: document vistest and OldestXmin.

  3. heap pruning: Only call BufferGetBlockNumber() once.

  4. Fix possible HOT corruption when RECENTLY_DEAD changes to DEAD while pruning.

  5. Assert redirect pointers are sensible after heap_page_prune().

  6. Remove tupgone special case from vacuumlazy.c.

  7. Recycle nbtree pages deleted during same VACUUM.

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

  9. Refactor heap_page_prune so that instead of changing item states on-the-fly,