Re: Reproducible GIST index corruption under concurrent updates

On 19/01/2021 19:12, Andrey Borodin wrote:
>> 19 янв. 2021 г., в 16:15, Duncan Sands <duncan(dot)sands(at)deepbluecap(dot)com> написал(а):
>>
>> Enjoy!
>
> Thanks!
> It reproduces on my machine. Seems like all tuples are indexed, but some root downlinks are not adjusted properly. Probably, after concurrent split.

This is reproducable down to v12. I bisected it to this commit:

commit e2e992c93145cfc0e3563fb84efd25b390a84bb9 (refs/bisect/bad)
Author: Heikki Linnakangas <heikki(dot)linnakangas(at)iki(dot)fi>
Date: Wed Jul 24 20:24:05 2019 +0300

Refactor checks for deleted GiST pages.

The explicit check in gistScanPage() isn't currently really
necessary, as
a deleted page is always empty, so the loop would fall through without
doing anything, anyway. But it's a marginal optimization, and it
gives a
nice place to attach a comment to explain how it works.

Backpatch to v12, where GiST page deletion was introduced.

Reviewed-by: Andrey Borodin
Discussion:
https://www.postgresql.org/message-id/835A15A5-F1B4-4446-A711-BF48357EB602%40yandex-team.ru

I'll dig deeper tomorrow.

- Heikki