Horton

Re: Logical Replication of sequences

Shlok Kyal <shlok.kyal.oss@gmail.com>

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From: Shlok Kyal <shlok.kyal.oss@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>, Chao Li <li.evan.chao@gmail.com>, shveta malik <shveta.malik@gmail.com>, Shinya Kato <shinya11.kato@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Euler Taveira <euler@eulerto.com>, Michael Paquier <michael@paquier.xyz>, "Jonathan S. Katz" <jkatz@postgresql.org>
Date: 2025-12-24T06:45:19Z
Lists: pgsql-hackers

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On Mon, 22 Dec 2025 at 11:08, Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Thu, Dec 18, 2025 at 12:37 PM Shlok Kyal <shlok.kyal.oss@gmail.com> wrote:
> >
> > While working on another thread, I noticed a bug introduced by commit
> > as part of this thread.
> > In function pg_get_publication_tables, We have code:
> > ```
> >                      if (pub_elem->alltables)
> > pub_elem_tables = GetAllPublicationRelations(RELKIND_RELATION,
> >  pub_elem->pubviaroot);
> > else
> > {
> > List     *relids,
> >    *schemarelids;
> >
> > relids = GetPublicationRelations(pub_elem->oid,
> >  pub_elem->pubviaroot ?
> >  PUBLICATION_PART_ROOT :
> >  PUBLICATION_PART_LEAF);
> > schemarelids = GetAllSchemaPublicationRelations(pub_elem->oid,
> > pub_elem->pubviaroot ?
> > PUBLICATION_PART_ROOT :
> > PUBLICATION_PART_LEAF);
> > pub_elem_tables = list_concat_unique_oid(relids, schemarelids);
> > }
> > ```
> >
> > So, when we create an 'ALL SEQUENCE publication' and we execute
> > 'SELECT * from pg_publication_tables'
> > We will enter the else condition in the above code, which does not
> > seem correct to me.
> > It will call functions which are not required to be called. It will
> > also call the function 'GetPublicationRelations' which contradicts the
> > comment above this function.
> >
>
> I see that we will needlessly call GetPublicationRelations or others
> for all_schema publication but is there any problem/bug due to that?
No, I did not encounter a problem/bug.

> AFAICS, the function will still return correct results. Yes, there is
> an argument to better performance for large numbers of all_sequence
> publications and that too in DDL like Create/Alter Subscription. I am
> not sure that it is really worth adding more checks at multiple places
> in the code though we can improve comments atop
> GetPublicationRelations. I feel if we encounter such cases in the
> field then it makes sense to add these additional optimizations at
> various places.
>
I agree with you. And attached a patch to modify the comment above
GetPublicationRelations.

Thanks,
Shlok Kyal