Horton

Re: Unexpected Standby Shutdown on sync_replication_slots change

Xuneng Zhou <xunengzhou@gmail.com>

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From: Xuneng Zhou <xunengzhou@gmail.com>
To: shveta malik <shveta.malik@gmail.com>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>, Fujii Masao <masao.fujii@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Hugo DUBOIS <hdubois@scaleway.com>, pgsql-bugs@lists.postgresql.org
Date: 2025-08-02T04:28:05Z
Lists: pgsql-bugs

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  1. Disallow server start with sync_replication_slots = on and wal_level < logical.

  2. Avoid unexpected shutdown when sync_replication_slots is enabled.

Hi,

On Wed, Jul 30, 2025 at 11:15 AM shveta malik <shveta.malik@gmail.com> wrote:
>
> On Tue, Jul 29, 2025 at 12:04 PM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
> >
> > On Tue, 2025-07-29 at 13:40 +0900, Fujii Masao wrote:
> > > I think it's basically not acceptable for a server to start up
> > > successfully before a minor version update, but then fail to start with
> > > the same configuration after the update. If that's absolutely necessary
> > > to fix a bug, it might be justifiable. But in this case, I don't think
> > > it's required.
> > >
> > > Blocking startup when sync_replication_slots is enabled and wal_level
> > > is not logical could be helpful. But that feels more like an improvement
> > > than a bug fix. I'm fine adding that to master, but I don't think we should
> > > apply it to old branches.
> > >
> > > That said, both Shveta and Amit support backpatching this change,
> > > so I'd like to hear more opinions before we decide.
> >
> > I side with you on that one.
> >
> > I think it would be fine to backpatch the breaking change to v18,
> > if we mention the behavior change in the release notes.
> >
>
> I am fine with the suggestion.

+ 1

This fix does feel more like an enhancement to user feedback and
safety nets, not a correction of a broken or unsafe code path. Unable
to start up with the same settings for it might cause
more-than-necessary surprise.

Best,
Xuneng