Re: clarifying trigger/rule behavior on logical replication subscribers

On Wed, Jun 7, 2023 at 4:09 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> On Wed, 7 Jun 2023 at 10:17, Jonathan S. Katz <jkatz(at)postgresql(dot)org> wrote:
> >
> > Hi,
> >
> > While answering a question on "do triggers fire on a logical replication
> > subscriber by default?" I tried to look up a reference to this behavior
> > in the docs. There wasn't a clear reference point, but on the
> > architecture page[1], I found this line that was closest to the answer:
> >
> > "The apply process on the subscriber database always runs with
> > session_replication_role set to replica, which produces the usual
> > effects on triggers and constraints."
> >
> > which assumes that the reader knows what the "usual effects" are.
> >
> > Attached is a patch that disambiguates this.
> >

I agree that it is a good idea to be explicit about this behavior. As
mentioned by you, it would be better to backpatch this. Also, I
thought about moving this to some other section like [1] but I think
we need to explain a bit about apply worker before providing this
specific information. So, the current place seems to be the best bet
considering the way current logical replication is documented.

[1] - https://www.postgresql.org/docs/devel/logical-replication-subscription.html

--
With Regards,
Amit Kapila.