Re: row filtering for logical replication

On Tue, Jul 20, 2021 at 5:13 PM Greg Nancarrow <gregn4422(at)gmail(dot)com> wrote:
>
> On Tue, Jul 20, 2021 at 6:29 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > I think in terms of referring to old and new rows, we already have
> > terminology which we used at various other similar places. See Create
> > Rule docs [1]. For where clause, it says "Within condition and
> > command, the special table names NEW and OLD can be used to refer to
> > values in the referenced table. NEW is valid in ON INSERT and ON
> > UPDATE rules to refer to the new row being inserted or updated. OLD is
> > valid in ON UPDATE and ON DELETE rules to refer to the existing row
> > being updated or deleted.". We need similar things for the WHERE
> > clause in publication if we want special syntax to refer to old and
> > new rows.
> >
>
> I have no doubt we COULD allow references to OLD and NEW in the WHERE
> clause, but do we actually want to?
> This is what I thought could cause confusion, when mixed with the
> model that I previously described.
> It's not entirely clear to me exactly how it works, when the WHERE
> clause is applied to the OLD and NEW rows, when the WHERE condition
> itself can refer to OLD and/or NEW (coupled with the fact that NEW
> doesn't make sense for DELETE and OLD doesn't make sense for INSERT).
>

It is not new, the same is true when they are used in RULES and
probably in other places where we use them.

--
With Regards,
Amit Kapila.