Re: Logical Replication - behavior of ALTER PUBLICATION .. DROP TABLE and ALTER SUBSCRIPTION .. REFRESH PUBLICATION

On Tue, 12 Jan 2021 at 19:32, Bharath Rupireddy wrote:
> On Tue, Jan 12, 2021 at 4:47 PM Li Japin <japinli(at)hotmail(dot)com> wrote:
>> IIUC the logical replication only replicate the tables in publication, I think
>> when the tables that aren't in publication should not be replicated.
>>
>> Attached the patch that fixes it. Thought?
>
> With that change, we don't get the behaviour that's stated in the
> document - "The ADD TABLE and DROP TABLE clauses will add and remove
> one or more tables from the publication. Note that adding tables to a
> publication that is already subscribed to will require a ALTER
> SUBSCRIPTION ... REFRESH PUBLICATION action on the subscribing side in
> order to become effective" -
> https://www.postgresql.org/docs/devel/sql-alterpublication.html.
>

The documentation only emphasize adding tables to a publication, not
include dropping tables from a publication.

> The publisher stops sending the tuples whenever the relation gets
> dropped from the publication, not waiting until alter subscription ...
> refresh publication on the subscriber.
>

If we want to wait the subscriber executing alter subscription ... refresh publication,
maybe we should send some feedback to walsender. How can we send this feedback to
walsender in non-walreceiver process?

> With Regards,
> Bharath Rupireddy.
> EnterpriseDB: http://www.enterprisedb.com

--
Regrads,
Japin Li.
ChengDu WenWu Information Technology Co.,Ltd.