Horton

Re: Implement waiting for wal lsn replay: reloaded

Alexander Korotkov <aekorotkov@gmail.com>

View thread
From: Alexander Korotkov <aekorotkov@gmail.com>
To: Xuneng Zhou <xunengzhou@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>, Álvaro Herrera <alvherre@kurilemu.de>, Michael Paquier <michael@paquier.xyz>, jian he <jian.universality@gmail.com>, Tomas Vondra <tomas@vondra.me>, Yura Sokolov <y.sokolov@postgrespro.ru>
Date: 2025-12-18T12:25:43Z
Lists: pgsql-hackers 
On Thu, Dec 18, 2025 at 2:24 PM Xuneng Zhou <xunengzhou@gmail.com> wrote:
> On Thu, Dec 18, 2025 at 6:38 PM Alexander Korotkov <aekorotkov@gmail.com> wrote:
> >
> > Hi, Xuneng!
> >
> > On Tue, Dec 16, 2025 at 6:46 AM Xuneng Zhou <xunengzhou@gmail.com> wrote:
> > > Remove the erroneous WAIT_LSN_TYPE_COUNT case from the switch
> > > statement in v5 patch 1.
> >
> > Thank you for your work on this patchset.  Generally, it looks like
> > good and quite straightforward extension of the current functionality.
> > But this patch adds 4 new unreserved keywords to our grammar.  Do you
> > think we can put mode into with options clause?
> >
>
> Thanks for pointing this out. Yeah, 4 unreserved keywords add
> complexity to the parser and it may not be worthwhile since replay is
> expected to be the common use scenario. Maybe we can do something like
> this:
>
> -- Default (REPLAY mode)
> WAIT FOR LSN '0/306EE20' WITH (TIMEOUT '1s');
>
> -- Explicit REPLAY mode
> WAIT FOR LSN '0/306EE20' WITH (MODE 'replay', TIMEOUT '1s');
>
> -- WRITE mode
> WAIT FOR LSN '0/306EE20' WITH (MODE 'write', TIMEOUT '1s');
>
> If no mode is set explicitly in the options clause, it defaults to
> replay. I'll update the patch per your suggestion.

This is exactly what I meant.  Please, go ahead.

------
Regards,
Alexander Korotkov
Supabase