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From: Alexander Korotkov <aekorotkov@gmail.com>
Date: Mon, 20 Apr 2026 13:21:36 +0300
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Subject: Re: test: avoid redundant standby catchup in 049_wait_for_lsn
To: Xuneng Zhou <xunengzhou@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>,
 pgsql-hackers <pgsql-hackers@lists.postgresql.org>
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On Sat, Apr 18, 2026 at 10:58=E2=80=AFAM Alexander Korotkov
<aekorotkov@gmail.com> wrote:
> On Sat, Apr 18, 2026 at 7:20=E2=80=AFAM Xuneng Zhou <xunengzhou@gmail.com=
> wrote:
> >> On Fri, Apr 17, 2026 at 08:25:35PM +0800, Xuneng Zhou wrote:
> >> > The change preserves the same coverage while removing one redundant
> >> > replay catch-up on the delayed standby. It appears to reduce the tes=
t
> >> > runtime by about 7 seconds, though I have looked into why much of th=
e
> >> > improvement comes from this change alone.
> >>
> >> Alexander may think differently and remove that, but I disagree.  The
> >> test is clearly written so as we want two wait checks to happen, for
> >> for CREATE FUNCTION, and one for CREATE PROCEDURE.  Removing the first
> >> check to keep only the second one removes its meaning.  In short, I
> >> see nothing wrong to deal with here.
> >
> >
> > Thank you for the review. I agree that the two wait checks serve distin=
ct purposes and are not redundant. The main motivation for this patch was e=
fficiency. In my testing, the new test added approximately 7 seconds to the=
 runtime, while the creation of the procedure and function completed quickl=
y. I suspect the latency stems from the wait-for-catch-up step. When I remo=
ved it, the test runtime dropped by about 7 seconds.I haven't yet investiga=
ted why the wait is so costly in this case. I should probably look into tha=
t before proposing this change.
>
> On my laptop the time needed to run t/049_wait_for_lsn.pl also drops
> from 20 secs to 12 secs.  The influence to the runtime of the whole
> test suite in parallel would be not that big as CPU time only drops
> from 2.16 sec to 2.07 sec.  But anyway that's pretty significant.
> I've revised comment message a bit and surrounding comments.  I'm
> going to push this if no objections.

Pushed.

------
Regards,
Alexander Korotkov
Supabase