Re: Handle infinite recursion in logical replication setup

On Wed, Apr 6, 2022 at 9:36 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Tue, Apr 5, 2022 at 7:06 PM Ashutosh Bapat
> <ashutosh.bapat.oss@gmail.com> wrote:
> >
> > On Tue, Apr 5, 2022 at 6:21 AM Peter Smith <smithpb2250@gmail.com> wrote:
> > >
> > > Below are some other name ideas. Maybe they are not improvements, but
> > > it might help other people to come up with something better.
> > >
> > > subscribe_publocal_only = true/false
> > > origin = pub_only/any
> > > adjacent_data_only = true/false
> > > direct_subscriptions_only = true/false
> > > ...
> >
> > FWIW, The subscriber wants "changes originated on publisher". From
> > that angle origin = publisher/any looks attractive. It also leaves
> > open the possibility that the subscriber may ask changes from a set of
> > origins or even non-publisher origins.
> >
>
> So, how are you imagining extending it for multiple origins? I think
> we can have multiple origins data on a node when there are multiple
> subscriptions pointing to the different or same node. The origin names
> are internally generated names but are present in
> pg_replication_origin. So, are we going to ask the user to check that
> table and specify it as an option? But, note, that the user may not be
> able to immediately recognize which origin data is useful for her.
>

I still don't have a very clear answer for the usability aspect but it
seems this was discussed in PGCon-Unconference [1] (Section: Origin
filter) and there also it was suggested to allow users to specify
multiple origin names. So, probably Ashutosh's idea makes sense and we
should use "origin = publisher/any or origin=local/any". Among these,
I would prefer later.

Note: I don't have email-id of Julian Markwort who has raised this
topic in Unconference. Euler, if you know, it might be better to add
him here, so that he is aware of what is going on and share his
opinion if he wishes to.

[1] - https://wiki.postgresql.org/wiki/PgCon_2022_Developer_Unconference

-- 
With Regards,
Amit Kapila.