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

Hi,

On November 18, 2021 6:55:08 PM PST, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
>On Thu, Nov 18, 2021 at 4:36 PM Andres Freund <andres(at)anarazel(dot)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

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