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From: Fujii Masao <masao.fujii@gmail.com>
Date: Fri, 6 Feb 2026 09:43:50 +0900
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Subject: Re: Placement of synchronized_standby_slots description in
 config.sgml
To: Shinya Kato <shinya11.kato@gmail.com>
Cc: pgsql-docs@lists.postgresql.org
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On Thu, Feb 5, 2026 at 3:47=E2=80=AFPM Shinya Kato <shinya11.kato@gmail.com=
> wrote:
>
> On Fri, Jan 23, 2026 at 7:22=E2=80=AFPM Fujii Masao <masao.fujii@gmail.co=
m> wrote:
> >
> > Hi,
> >
> > synchronized_standby_slots is defined in guc_parameter.dat as part of
> > the REPLICATION_PRIMARY group and appears under the "Primary Server"
> > section in postgresql.conf.sample. However, in the documentation
> > its description is placed under the "Sending Servers" section.
> >
> > Given this, it seems the description should also be under "Primary Serv=
er"
> > in the documentation. I've attached a patch that moves it there.
>
> Thank you for the patch! The patch LGTM.

Thanks for the review! I've pushed the patch.


> > Alternatively, if synchronized_standby_slots is intended to be set also
> > on a standby in cascading replication setups, then the current document=
ation
> > placement may be correct, and instead guc_parameter.dat and
> > postgresql.conf.sample should be updated. My understanding, though,
> > is that this parameter is normally set only on the primary. Right?
>
> You're right. PhysicalWakeupLogicalWalSnd() in walsender.c has this check=
:
>
>     /*
>      * If we are running in a standby, there is no need to wake up walsen=
ders.
>      * This is because we do not support syncing slots to cascading stand=
bys,
>      * so, there are no walsenders waiting for standbys to catch up.
>      */
>     if (RecoveryInProgress())
>         return;
>
> So this parameter is only meaningful on the primary.

Thanks for confirming this!

Regards,

--=20
Fujii Masao