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From: Amit Kapila <amit.kapila16@gmail.com>
Date: Wed, 18 Mar 2026 19:26:10 +0530
Message-ID: 
 <CAA4eK1KoSi60dtakJzn0MxNnHF1Yf4indSAffTjJxQG_31jsgQ@mail.gmail.com>
Subject: Re: Initial COPY of Logical Replication is too slow
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>,
 Marcos Pegoraro <marcos@f10.com.br>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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On Tue, Mar 10, 2026 at 3:40=E2=80=AFAM Masahiko Sawada <sawada.mshk@gmail.=
com> wrote:
>
> On Tue, Mar 3, 2026 at 2:22=E2=80=AFAM Zhijie Hou (Fujitsu)
> <houzj.fnst@fujitsu.com> wrote:
> >
> > On Saturday, February 28, 2026 7:48 AM Masahiko Sawada <sawada.mshk@gma=
il.com> wrote:
> > > To: Marcos Pegoraro <marcos@f10.com.br>
> > > Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
> > > Subject: Re: Initial COPY of Logical Replication is too slow
> > >
> > > Another variant of this approach is to extend
> > > pg_get_publication_table() so that it can accept a relid to get the p=
ublication
> > > information of the specific table. I've attached the patch for this i=
dea. I'm
> > > going to add regression test cases.
> > >
> > > pg_get_publication_table() is a VARIACID array function so the patch =
changes
> > > its signature to {text[] [, oid]}, breaking the tool compatibility. G=
iven this
> > > function is mostly an internal-use function (we don't have the docume=
ntation
> > > for it), it would probably be okay with it. I find it's clearer than =
the other
> > > approach of introducing pg_get_publication_table_info(). Feedback is =
very
> > > welcome.
> >
> > Thanks for updating the patch.
> >
> > I have few comments for the function change:
> >
> > 1.
> >
> > If we change the function signature, will it affect use cases where the
> > publisher version is newer and the subscriber version is older ? E.g., =
when
> > publisher is passing text style publication name to pg_get_publication_=
tables().
>
> Good point.
>
> I noticed that changing the function signature of
> pg_get_publication_tables() breaks logical replication setups where
> the subscriber is 18 or older.
>

Why adding a new function with additional parameters (Oid relid)
couldn't help with such a case? I am asking because your previous
version code looks simpler as compared to the new patch version.

--=20
With Regards,
Amit Kapila.