Re: IRe: BUG #16792: silent corruption of GIN index resulting in SELECTs returning non-matching rows

On Thu, Jul 15, 2021 at 4:27 PM Pawel Kudzia <kudzia@gmail.com> wrote:
> > On Fri, Jun 25, 2021 at 11:48 PM Alexander Korotkov
> > <aekorotkov@gmail.com> wrote:
> > > Do you think it also worth checking whether bug persists when set
> > > fastupdate = off.  Then we could localize whether bug is related to
> > > pending lists.
> >
> > I still think this is worth checking.  Despite the pending list wasn't
> > involved in the index scan with wrong results, the bug could be
> > related to insertion to the pending list.  Or it could be related to
> > moving entries from the pending list to the posting list/tree.
> >
>
> regarding fastupdate - i'd like to clarify. do i understand correctly
> that this parameter affects what happens when rows are
> inserted/updated/deleted?

Yes, that's it.

> if yes - we no longer have such workload on the production and we
> cannot anymore and i was never able to find reproducible scenario.
> the production environment was moved away from index built "USING gin
> (attribute_name_ids public.gin__int_ops)" to index "USING gin
> (attribute_name_ids)".

Do I understand correctly that after the production environment moved
away from the usage of contrib/intarray opclass to builtin opclass,
the error has gone?

> the only thing i have right two file-level backups of postgresql data
> directory on which i know that SELECTs return rows that actually don't
> meet provided criteria.
>
> is there any point in testing fastupdate = off on those two snapshots?

OK, I see.  No point in trying fastupdate = off unless we can try to
reproduce the index corruption.