Re: Initial COPY of Logical Replication is too slow

On Tue, Mar 10, 2026 at 3:40 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Tue, Mar 3, 2026 at 2:22 AM Zhijie Hou (Fujitsu)
> <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> >
> > On Saturday, February 28, 2026 7:48 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > > To: Marcos Pegoraro <marcos(at)f10(dot)com(dot)br>
> > > Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)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 publication
> > > information of the specific table. I've attached the patch for this idea. 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. Given this
> > > function is mostly an internal-use function (we don't have the documentation
> > > 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.

--
With Regards,
Amit Kapila.