On Fri, Jan 14, 2022 at 7:08 PM Alvaro Herrera <alvhe...@alvh.no-ip.org> wrote: > > On 2022-Jan-14, Amit Kapila wrote: > > > 1. Replica Identity handling: Currently the column filter patch gives > > an error during create/alter subscription if the specified column list > > is invalid (Replica Identity columns are missing). It also gives an > > error if the user tries to change the replica identity. However, it > > doesn't deal with cases where the user drops and adds a different > > primary key that has a different set of columns which can lead to > > failure during apply on the subscriber. > > Hmm, yeah, I suppose we should check that the primary key is compatible > with the column list in all publications. (I wonder what happens in the > interim, that is, what happens to tuples modified after the initial PK > is dropped and before the new PK is installed. Are these considered to > have "replica identiy nothing"?) >
I think so. > > I think another issue w.r.t column filter patch is that even while > > creating publication (even for 'insert' publications) it should check > > that all primary key columns must be part of published columns, > > otherwise, it can fail while applying on subscriber as it will try to > > insert NULL for the primary key column. > > I'm not so sure about the primary key aspects, actually; keep in mind > that the replica can have a different table definition, and it might > have even a completely different primary key. I think this part is up > to the user to set up correctly; we have enough with just trying to make > the replica identity correct. > But OTOH, the primary key is also considered default replica identity, so I think users will expect it to work. You are right this problem can also happen if the user defined a different primary key on a replica but that is even a problem in HEAD (simple inserts will fail) but I am worried about the case where both the publisher and subscriber have the same primary key as that works in HEAD. -- With Regards, Amit Kapila.
