Re: ERROR: found multixact from before relminmxid

On 2018-06-08 12:38:03 -0500, Jeremy Finzel wrote:
> On Tue, Jun 5, 2018 at 8:42 PM, Alexandre Arruda <adaldeia(at)gmail(dot)com> wrote:
>
> > Em seg, 28 de mai de 2018 às 16:44, Andres Freund <andres(at)anarazel(dot)de>
> > escreveu:
> > >
> > > Hi,
> > >
> > > I think I found the bug, and am about to post a fix for it belo
> > > https://postgr.es/m/20180525203736.crkbg36muzxrjj5e@alap3.anarazel.de.
> > >
> > > Greetings,
> > >
> > > Andres Freund
> >
> > Hi Andres,
> >
> > In end of April we did a complete dump/reload in database to version 10.3.
> > Today, the problem returns:
> >
> > production=# vacuum verbose co27t;
> > INFO: vacuuming "public.co27t"
> > ERROR: found multixact 81704071 from before relminmxid 107665371
> > production=# vacuum full verbose co27t;
> > INFO: vacuuming "public.co27t"
> > ERROR: found multixact 105476076 from before relminmxid 107665371
> > production=# cluster co27t;
> > ERROR: found multixact 105476076 from before relminmxid 107665371
> >
> > But this time, regular vacuum versus full/cluster are different in
> > multixact number.
> > Your patch is applicable to this issue and is in 10.4 ?
> >
> > Best regards,
> >
> > Alexandre
> >
> >
> We encountered this issue ourselves for the first time on a busy OLTP
> system. It is at 9.6.8. We found that patching to 9.6.9 on a snapshot of
> this system did not fix the problem, but I assume that is because the patch
> in 9.6.9 only prevents the problem moving forward. Is that accurate?

Which patch in 9.6.9 are you referring to? The patch I linked to above
hasn't yet been merged, much less been released.

Unfortunately, on second thought, I don't quite see how it applies to
the cases here (rather than other reports about pg_authid and such). So
there might be a separate issue. Is there any chance I could get access
to a copy of the data? It's very hard to debug something like this
without something that can reproduce the issue...

Greetings,

Andres Freund