Re: pg_get_publication_tables() output duplicate relid

On Thu, Nov 18, 2021 at 9:33 houzj(dot)fnst(at)fujitsu(dot)com <houzj(dot)fnst(at)fujitsu(dot)com>
wrote:

> On Wed, Nov 17, 2021 2:18 PM Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> > On Wed, Nov 17, 2021 at 12:15 PM houzj(dot)fnst(at)fujitsu(dot)com
> > <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> > > On Wed, Nov 17, 2021 10:47 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
> > wrote:
> > > > On Tue, Nov 16, 2021 at 7:21 AM houzj(dot)fnst(at)fujitsu(dot)com wrote:
> > > > > If we decide to disallow this case, we seem need to handle some
> other
> > > > > cases as well, for example: We might also need additional check
> when
> > > > > ATTACH a partition, because the partition's parent table could
> already
> > > > > be published in the same publication as the partition.
> > > > >
> > > >
> > > > What kind of additional checks you are envisioning and why?
> > >
> > > For example:
> > >
> > > create table tbl1 (a int) partition by range (a);
> > > create table tbl1_part1 (like tbl1);
> > > create table tbl1_part2 partition of tbl1 for values from (10) to (20);
> > > create publication pub for table
> > > tbl1, tbl1_part1 with (publish_via_partition_root=false);
> > >
> > > --- We might need addition check here
> > > Alter table tbl1 ATTACH partition tbl1_part1 for values from (1) to
> (10);
> > >
> > > In the above cases, 'tbl1_part1' is not a partition of 'tb1' when
> creating a
> > > publication. After the ATTACH, 'tbl1_part1' would become a partition
> of 'tbl1'
> > > which seems the case we want to disallow(both parent and child table in
> > > publication). So, When ATTACH, I thought we might need to check all
> the parent
> > > tables to see if any parent table is in the same publication which the
> table to
> > > be attached is also belongs to. Does it make sense ?
> >
> > I don't think creating or attaching a partition of a table that is
> > present in a publish_via_partition_root=false actually adds the
> > partition to pg_publication_rel, the base catalog. A partition's
> > membership in the publication is implicit, unless of course you add it
> > to the publication explicitly, like all the examples we have been
> > discussing. I guess we're only arguing about the problems with the
> > pg_publication_tables view, which does expand the partitioned table to
> > show the partitions that are not otherwise not present in the base
> > catalog.
>
> Maybe I didn't make it clear, I was trying to explain that it would be
> complicated if we want to completely disallow specifying both child and
> parent
> table in the publication because of the ATTACH case I gave. In other
> words, I
> think it's fine to specify both child and parent table in the publication.

Ah okay. I see your point. A table that was not once a partition would be
in the catalog along with the unrelated parent table and if we were to
enforce the rule that a parent and a partition cannot be in the catalog at
the same time, we’d need to delete that table’s catalog record on ATTACHing
it as a partition.

Thanks.
--
Amit Langote
EDB: http://www.enterprisedb.com