Re: Regardign RecentFlushPtr in WalSndWaitForWal()

On Fri, Mar 1, 2024 at 4:40 PM Matthias van de Meent
<boekewurm+postgres(at)gmail(dot)com> wrote:
>
> On Mon, 26 Feb 2024 at 12:46, shveta malik <shveta(dot)malik(at)gmail(dot)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(at)postgresql(dot)org>
Date: Mon Mar 10 13:50:28 2014 -0400

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