On Mon, Jul 10, 2023 at 7:26 PM Sergei Kornilov <s...@zsrv.org> wrote: > > >> Is this restriction only for the subscriber? > >> > >> If we have not changed the replica identity and there is no primary key, > >> then we forbid update and delete on the publication side (a fairly common > >> usage error at the beginning of using publications). > >> If we have replica identity FULL (the table has such a column), then on > >> the subscription side, update and delete will be performed. > > > > In the above sentence, do you mean the publisher side? > > Yep, sorry. > > > But we will not be able to apply them on a subscription. Right? > > > > If your previous sentence talks about the publisher and this sentence > > about the subscriber then what you are saying is correct. You can see > > the example in the email [1]. > > Thank you > > >> This is an important difference for real use, when the subscriber is not > >> necessarily postgresql - for example, debezium. > > > > Can you explain the difference and problem you are seeing? As per my > > understanding, this is the behavior from the time logical replication > > has been introduced. > > The difference is that if it's a subscriber-only restriction, then it won't > automatically apply to anyone with a non-postgresql subscriber. > But if suddenly this would be a limitation of the publisher - then it will > automatically apply to everyone, regardless of which subscriber is used. > (and it's a completely different problem if the restriction affects the > update/delete themselves, not only their replication. Like as default replica > identity on table without primary key, not in this case) > > So, I suggest to mention subscriber explicitly: > > + class of Btree, then <literal>UPDATE</literal> and > <literal>DELETE</literal> > - operations cannot be replicated. > + operations cannot be applied on subscriber. > > Another example of difference: > Debezium users sometimes ask to set identity to FULL to get access to old > values: https://stackoverflow.com/a/59820210/10983392 > However, identity FULL is described in the documentation as: > https://www.postgresql.org/docs/current/logical-replication-publication.html >
After seeing this, I am thinking about whether we add this restriction on the Subscription page [1] or Restrictions page [2] as proposed. Do you others have any preference? [1] - https://www.postgresql.org/docs/devel/logical-replication-subscription.html [2] - https://www.postgresql.org/docs/devel/logical-replication-restrictions.html -- With Regards, Amit Kapila.
