Re: Introduce XID age and inactive timeout based replication slot invalidation

On Wed, Apr 3, 2024 at 8:28 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> On Wed, Apr 3, 2024 at 6:46 PM Bertrand Drouvot
> <bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
> >
> > Just one comment on v32-0001:
> >
> > +# Synced slot on the standby must get its own inactive_since.
> > +is( $standby1->safe_psql(
> > + 'postgres',
> > + "SELECT '$inactive_since_on_primary'::timestamptz <= '$inactive_since_on_standby'::timestamptz AND
> > + '$inactive_since_on_standby'::timestamptz <= '$slot_sync_time'::timestamptz;"
> > + ),
> > + "t",
> > + 'synchronized slot has got its own inactive_since');
> > +
> >
> > By using <= we are not testing that it must get its own inactive_since (as we
> > allow them to be equal in the test). I think we should just add some usleep()
> > where appropriate and deny equality during the tests on inactive_since.
>
> Thanks. It looks like we can ignore the equality in all of the
> inactive_since comparisons. IIUC, all the TAP tests do run with
> primary and standbys on the single BF animals. And, it looks like
> assigning the inactive_since timestamps to perl variables is giving
> the microseconds precision level
> (./tmp_check/log/regress_log_040_standby_failover_slots_sync:inactive_since
> 2024-04-03 14:30:09.691648+00). FWIW, we already have some TAP and SQL
> tests relying on stats_reset timestamps without equality. So, I've
> left the equality for the inactive_since tests.
>
> > Except for the above, v32-0001 LGTM.
>
> Thanks. Please see the attached v33-0001 patch after removing equality
> on inactive_since TAP tests.
>

The v33-0001 looks good to me. I have made minor changes in the
comments/commit message and removed one part of the test which was a
bit confusing and didn't seem to add much value. Let me know what you
think of the attached?

--
With Regards,
Amit Kapila.