Re: Implement waiting for wal lsn replay: reloaded

From: Xuneng Zhou <xunengzhou(at)gmail(dot)com>
To: Alexander Korotkov <aekorotkov(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de>, Álvaro Herrera <alvherre(at)kurilemu(dot)de>, Michael Paquier <michael(at)paquier(dot)xyz>, jian he <jian(dot)universality(at)gmail(dot)com>, Tomas Vondra <tomas(at)vondra(dot)me>, Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru>
Subject: Re: Implement waiting for wal lsn replay: reloaded
Date: 2025-12-19 02:49:46
Message-ID: CABPTF7V0xMVS=U-pdFADDe6WEoGJ7jWZt7pffXfnmePfLWjZjg@mail.gmail.com
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Hi,

On Thu, Dec 18, 2025 at 8:25 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
>
> On Thu, Dec 18, 2025 at 2:24 PM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
> > On Thu, Dec 18, 2025 at 6:38 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
> > >
> > > Hi, Xuneng!
> > >
> > > On Tue, Dec 16, 2025 at 6:46 AM Xuneng Zhou <xunengzhou(at)gmail(dot)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.
>

Here is the updated patch set (v7). Please check.

--
Best,
Xuneng

Attachment Content-Type Size
v7-0001-Extend-xlogwait-infrastructure-with-write-and-flu.patch application/octet-stream 10.9 KB
v7-0004-Use-WAIT-FOR-LSN-in.patch application/octet-stream 3.0 KB
v7-0003-Add-tab-completion-for-WAIT-FOR-LSN-MODE-option.patch application/octet-stream 2.3 KB
v7-0002-Add-MODE-option-to-WAIT-FOR-LSN-command.patch application/octet-stream 34.8 KB

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