Re: Replication slot stats misgivings

On Wed, Apr 21, 2021 at 6:36 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Wed, Apr 21, 2021 at 2:46 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > On Wed, Apr 21, 2021 at 3:09 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > > On Tue, Apr 20, 2021 at 7:54 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > > >
> > > >
> > > > I've attached the patch. In addition to the test Vignesh prepared, I
> > > > added one test for the message for creating a slot that checks if the
> > > > statistics are initialized after re-creating the same name slot.
> > > >
> > >
> > > I am not sure how much useful your new test is because you are testing
> > > it for slot name for which we have removed the slot file. It is not
> > > related to stat messages this patch is sending. I think we can leave
> > > that for now.
> >
> > I might be missing something but I think the test is related to the
> > message for creating a slot that initializes all counters. No? If
> > there is no that message, we will end up getting old stats if a
> > message for dropping slot gets lost (simulated by dropping slot file)
> > and the same name slot is created.
> >
>
> The test is not waiting for a new slot creation message to reach the
> stats collector. So, if the old slot data still exists in the file and
> now when we read stats via backend, then won't there exists a chance
> that old slot stats data still exists?

You're right. We should wait for the message to reach the collector.
Or should we remove that test case?

Regards,

--
Masahiko Sawada
EDB: https://www.enterprisedb.com/