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From: Amit Kapila <amit.kapila16@gmail.com>
Date: Sat, 2 Mar 2024 16:44:28 +0530
Message-ID: <CAA4eK1+LO+x6RREH434TGw4E_TK1UnrDK8nTL0xLQb4uFEdVMg@mail.gmail.com>
Subject: Re: Regardign RecentFlushPtr in WalSndWaitForWal()
To: Matthias van de Meent <boekewurm+postgres@gmail.com>
Cc: shveta malik <shveta.malik@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, 
	Robert Haas <robertmhaas@gmail.com>
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On Fri, Mar 1, 2024 at 4:40=E2=80=AFPM Matthias van de Meent
<boekewurm+postgres@gmail.com> wrote:
>
> On Mon, 26 Feb 2024 at 12:46, shveta malik <shveta.malik@gmail.com> wrote=
:
> >
> > Hi hackers,
> >
> > I would like to understand why we have code [1] that retrieves
> > RecentFlushPtr in WalSndWaitForWal() outside of the loop. We utilize
> > RecentFlushPtr later within the loop, but prior to that, we already
> > have [2]. Wouldn't [2] alone be sufficient?
> >
> > Just to check the impact, I ran 'make check-world' after removing [1],
> > and did not see any issue exposed by the test at-least.
>
> Yeah, that seems accurate.
>
> > Any thoughts?
> [...]
> > [2]:
> >                 /* Update our idea of the currently flushed position. *=
/
> >                 else if (!RecoveryInProgress())
>
> I can't find where this "else" of this "else if" clause came from, as
> this piece of code hasn't changed in years.
>

Right, I think the quoted code has check "if (!RecoveryInProgress())".

>
 But apart from that, your
> observation seems accurate, yes.
>

I also find the observation correct and the code has been like that
since commit 5a991ef8 [1]. So, let's wait to see if Robert or Andres
remembers the reason, otherwise, we should probably nuke this code.


[1]
commit 5a991ef8692ed0d170b44958a81a6bd70e90585c
Author: Robert Haas <rhaas@postgresql.org>
Date:   Mon Mar 10 13:50:28 2014 -0400

    Allow logical decoding via the walsender interface.
--=20
With Regards,
Amit Kapila.