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

Hi,

On 2021-11-17 23:19:41 -0800, Andres Freund wrote:
> Not sure if it's worth it, but I think this can be made into a reliably
> isolationtest by causing a tables index to locked exclusively, blocking
> vac_open_indexes(), which can then reliably schedule a new relcache inval,
> which in turn can compute a new RecentXmin. Might be too fragile to be worth
> it.

Attached is such an isolationtest. In an unmodified HEAD it ends up with

step s1_select_1:
  SET LOCAL enable_seqscan = false;
  SELECT ctid, /*xmin, xmax, */ id FROM many_updates WHERE id = 1;
  RESET enable_seqscan;

ctid |id
-----+--
(0,3)|17
(1 row)

without amcheck detecting corruption at that point:(.


It's clearly not yet something we could consider committable, but I think it
might be a useful basis for such a test.

Greetings,

Andres Freund