Re: row filtering for logical replication

On Tue, Nov 23, 2021 at 1:29 PM houzj(dot)fnst(at)fujitsu(dot)com
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> On Tues, Nov 23, 2021 2:27 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> > On Thu, Nov 18, 2021 at 7:04 AM Peter Smith <smithpb2250(at)gmail(dot)com>
> > wrote:
> > >
> > > PSA new set of v40* patches.
> >
> > Few comments:
> > 1) When a table is added to the publication, replica identity is checked. But
> > while modifying the publish action to include delete/update, replica identity is
> > not checked for the existing tables. I felt it should be checked for the existing
> > tables too.
>
> In addition to this, I think we might also need some check to prevent user from
> changing the REPLICA IDENTITY index which is used in the filter expression.
>
> I was thinking is it possible do the check related to REPLICA IDENTITY in
> function CheckCmdReplicaIdentity() or In GetRelationPublicationActions(). If we
> move the REPLICA IDENTITY check to this function, it would be consistent with
> the existing behavior about the check related to REPLICA IDENTITY(see the
> comments in CheckCmdReplicaIdentity) and seems can cover all the cases
> mentioned above.
>

Yeah, adding the replica identity check in CheckCmdReplicaIdentity()
would cover all the above cases but I think that would put a premium
on each update/delete operation. I think traversing the expression
tree (it could be multiple traversals if the relation is part of
multiple publications) during each update/delete would be costly.
Don't you think so?

--
With Regards,
Amit Kapila.