Re: Wake up backends immediately when sync standbys decrease

Xuneng Zhou <xunengzhou@gmail.com>

From: Xuneng Zhou <xunengzhou@gmail.com>
To: Shinya Kato <shinya11.kato@gmail.com>
Cc: Fujii Masao <masao.fujii@gmail.com>, Chao Li <li.evan.chao@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-02-02T02:28:05Z
Lists: pgsql-hackers
Hi Kato-san,

Thanks for working on this.

On Sun, Feb 1, 2026 at 2:25 PM Shinya Kato <shinya11.kato@gmail.com> wrote:
>
> Thank you for the reviews!
>
> On Sat, Jan 31, 2026 at 12:28 AM Fujii Masao <masao.fujii@gmail.com> wrote:
> > This issue can occur not only when the number of sync standbys is reduced,
> > but also when the configured standby names change. For example, if the config
> > changes from "FIRST 2 (sby1, sby2)" to "FIRST 2 (sby1, sby3)",
> > waiters on sby2 should be released immediately. But, currently, there can
> > a delay before that happens. Right?
>
> Yes, you're right, so I revised the comments and commit message.
>
> > > My main concern is code duplication. The same block is added in three places. While the existing reload handling is already duplicated there, adding more logic on top makes the situation a bit worse from a maintenance perspective.
> > >
> > > Would it make sense to factor the reload handling into a small helper, for example:
> >
> > +1
>
> I've updated it in the v2 patch.
>
>
> --
> Best regards,
> Shinya Kato
> NTT OSS Center

v2 LGTM.

-- 
Best,
Xuneng



Commits

  1. Release synchronous replication waiters immediately on configuration changes.