Re: Add two missing tests in 035_standby_logical_decoding.pl - Mailing list pgsql-hackers

On Mon, Apr 24, 2023 at 5:38 PM Drouvot, Bertrand
<bertranddrouvot.pg@gmail.com> wrote:
>
> On 4/24/23 11:45 AM, Amit Kapila wrote:
> > On Mon, Apr 24, 2023 at 11:54 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >>
> >> On Mon, Apr 24, 2023 at 11:24 AM Drouvot, Bertrand
> >> <bertranddrouvot.pg@gmail.com> wrote:
> >>>
> >>
> >> Few comments:
> >> ============
> >>
> >
> > +# We can not test if the WAL file still exists immediately.
> > +# We need to let some time to the standby to actually "remove" it.
> > +my $i = 0;
> > +while (1)
> > +{
> > + last if !-f $standby_walfile;
> > + if ($i++ == 10 * $default_timeout)
> > + {
> > + die
> > +   "could not determine if WAL file has been retained or not, can't continue";
> > + }
> > + usleep(100_000);
> > +}
> >
> > Is this adhoc wait required because we can't guarantee that the
> > checkpoint is complete on standby even after using wait_for_catchup?
>
> Yes, the restart point on the standby is not necessary completed even after wait_for_catchup is done.
>
> > Is there a guarantee that it can never fail on some slower machines?
> >
>
> We are waiting here at a maximum for 10 * $default_timeout (means 3 minutes) before
> we time out. Would you prefer to wait more than 3 minutes at a maximum?
>

No, because I don't know what would be a suitable timeout here. At
this stage, I don't have a good idea on how to implement this test in
a better way. Can we split this into a separate patch as the first
test is a bit straightforward, we can push that one and then
brainstorm on if there is a better way to test this functionality.

--
With Regards,
Amit Kapila.