RE: pg_get_publication_tables() output duplicate relid

On Thursday, December 2, 2021 9:48 PM Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> On Thu, Dec 2, 2021 at 2:27 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > On Thu, Dec 2, 2021 at 8:42 AM Amit Langote <amitlangote09(at)gmail(dot)com>
> wrote:
> > > Reading Alvaro's email at the top again gave me a pause to
> > > reconsider what I had said in reply. It might indeed have been nice
> > > if the publication DDL itself had prevented the cases where a
> > > partition and its ancestor are added to a publication, though as
> > > Hou-san mentioned, partition ATTACHes make that a bit tricky to
> > > enforce at all times, though of course not impossible. Maybe it's
> > > okay to just de-duplicate pg_publication_tables output as the patch
> > > does, even though it may appear to be a band-aid solution if we one
> > > considers Alvaro's point about consistency.
> >
> > True, I think even if we consider that idea it will be a much bigger
> > change, and also as it will be a behavioral change so we might want to
> > keep it just for HEAD and some of these fixes need to be backpatched.
> > Having said that, if you or someone want to pursue that idea and come
> > up with a better solution than what we have currently it is certainly
> > welcome.
>
> Okay, I did write a PoC patch this morning after sending out my earlier email. I
> polished it a bit, which is attached.

After thinking more on this. I find there might be some usage about adding both
child and parent to the publication.

For the future feature publication row filter(and maybe column filter), It
could be useful for user to adding child and parent with different filter
expression. If pubviaroot=true, user can expect the parent's filter take
effect, If pubviaroot=false, they can expect the child's filter take effect.

If we disallow adding both child and parent to publication, it could be harder
for these features to implement.

So, personally, I am not sure disallow adding both child and parent to the
publication is a good idea.

Best regards,
Hou zj