Re: Disallow UPDATE/DELETE on table with unpublished generated column as REPLICA IDENTITY

On Fri, Nov 8, 2024 at 5:17 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2024-Nov-07, Amit Kapila wrote:
>
> > BTW, I was thinking as to how to fix it on back branches and it seems
> > we should restrict to define REPLICA IDENTITY on stored generated
> > columns in the first place in back branches as those can't be
> > replicated. So, the following should fail:
> >
> > CREATE TABLE testpub_gencol (a INT, b INT GENERATED ALWAYS AS (a + 1)
> > STORED NOT NULL);
> > CREATE UNIQUE INDEX testpub_gencol_idx ON testpub_gencol (b);
> > ALTER TABLE testpub_gencol REPLICA IDENTITY USING index testpub_gencol_idx;
> >
> > Peter, do you have an opinion on this?
>
> I think a blanket restriction of this sort is not a good idea (at least
> in back branches), because there might be people using replica
> identities with stacks other than pgoutput.
>

Do you mean to say that people using plugins other than pgoutput may
already be sending generated columns, so defining replica identity
should be okay for them?

>
>  Would it work to enforce
> the restriction when such a table is added to a publication?
>

But what if somebody defines REPLICA IDENTITY on the generated column
after adding the table to the publication?

--
With Regards,
Amit Kapila.