Re: pg14b1 stuck in lazy_scan_prune/heap_page_prune of pg_statistic

Hi,

On 2021-06-14 11:53:47 +0200, Matthias van de Meent wrote:
> On Thu, 10 Jun 2021 at 19:43, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> >
> > On Thu, Jun 10, 2021 at 10:29 AM Matthias van de Meent
> > <boekewurm+postgres(at)gmail(dot)com> wrote:
> > > I see one exit for HEAPTUPLE_DEAD on a potentially recently committed
> > > xvac (?), and we might also check against recently committed
> > > transactions if xmin == xmax, although apparently that is not
> > > implemented right now.
> >
> > I don't follow. Perhaps you can produce a test case?
>
> If you were to delete a tuple in the same transaction that you create
> it (without checkpoints / subtransactions), I would assume that this
> would allow us to vacuum the tuple, as the only snapshot that could
> see the tuple must commit or roll back.

Right now we do not do so, but I think we talked about adding such logic
a couple times.

I think a more robust assertion than aborted-ness could be to assert
that repeated retries are not allowed to have the same "oldest xid" than
a previous retry. With oldest xid be the older of xmin/xmax?

Greetings,

Andres Freund