Re: pg_createsubscriber: allow duplicate publication names

On Tue, Jun 2, 2026 at 1:29 PM Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>
> > On Jun 2, 2026, at 15:32, Hayato Kuroda (Fujitsu) <kuroda(dot)hayato(at)fujitsu(dot)com> wrote:
> >
> > Dear Chao, Amit,
> >
> >> In theory, yes, since subscription names are also unique per database. I didn’t
> >> include that in v1 because the publication-name issue affects the new PG19
> >> feature for reusing existing publications, whereas allowing duplicate subscription
> >> names seems like an improvement that could be a material of v20.
> >>
> >> As you ask, I put the subscription-name change in 0002. Please decide how to
> >> proceed. If you decide to accept both, they can be squashed.
> >
> > For subscription side, I had a concern that name duplication error can be more likely
> > to happen if we specify the same subscription name for two databases. Because the
> > same will be reused for the slot name. Reproducer:
> >
> > ```
> > $ pg_createsubscriber -D data_sta/ -P 'user=postgres port=5432' -d postgres --subscription sub -d testdb --subscription sub -U postgres
> > ...
> > pg_createsubscriber: error: could not create replication slot "sub" in database "testdb": ERROR: replication slot "sub" already exists
> > ```
> >

Can't we use --replication-slot=name to avoid this ERROR? I mean use
different replication slot names.

> > Personally -1 to accept the idea as-is.
> >
> > Best regards,
> > Hayato Kuroda
> > FUJITSU LIMITED
> >
>
> Good point. Allowing duplicate subscription names would require additional work, so let's leave that for v20. I'm going to withdraw 0002. I also updated 0001's commit message to explain why subscription names are excluded.
>

I was not suggesting to get the subscription work for PG19. Otherwise,
your patch for publication names looks good to me.

--
With Regards,
Amit Kapila.