Re: Replication slot stats misgivings

On Sun, Apr 18, 2021 at 9:02 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> On Sun, Apr 18, 2021 at 8:43 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Sun, Apr 18, 2021 at 7:36 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> > >
> > > On Sun, Apr 18, 2021 at 3:51 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > > >
> > > > I wrote:
> > > > > The buildfarm suggests that this isn't entirely stable:
> > > > > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=anole&dt=2021-04-17%2011%3A14%3A49
> > > > > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=bichir&dt=2021-04-17%2016%3A30%3A15
> > > >
> > > > Oh, I missed that hyrax is showing the identical symptom:
> > > >
> > > > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=hyrax&dt=2021-04-16%2007%3A05%3A44
> > > >
> > > > So you might try CLOBBER_CACHE_ALWAYS to see if you can reproduce it
> > > > that way.
> > > >
> > >
> > > I will try to check and identify why it is failing.
> > >
> >
> > I think the failure is due to the reason that in the new tests after
> > reset, we are not waiting for the stats message to be delivered as we
> > were doing in other cases. Also, for the new test (non-spilled case),
> > we need to decode changes as we are doing for other tests, otherwise,
> > it will show the old stats.
>
> I also felt that is the reason for the failure, I will fix and post a
> patch for this.

Attached a patch which includes the changes for the fix. I have moved
the non-spilled transaction test to reduce the steps which reduces
calling pg_logical_slot_get_changes before this test.

Regards,
Vignesh