BUG #18644: ALTER PUBLICATION ... SET (publish_via_partition_root) wrong/undocumented behavior.

The following bug has been logged on the website:

Bug reference: 18644
Logged by: Maxim Boguk
Email address: maxim(dot)boguk(at)gmail(dot)com
PostgreSQL version: 15.8
Operating system: Ubuntu
Description:

Hi,

When ALTER PUBLICATION ... SET (publish_via_partition_root) executed on the
existing logical replication with data
(following ALTER SUBSCRIPTION ... REFRESH PUBLICATION), the database start
copy whole partitioned table from start (thus breaking existing logical
replication).
What's worse - I didn't found any way get out of such situation less than
redo all multi-TB logical replication from blank db.

Also ALTER SUBSCRIPTION ... REFRESH PUBLICATION (copy_data=false) - cannot
be used as workaround because it lead to loose any changes in partitioned
table between run ALTER PUBLICATION and ALTER SUBSCRIPTION.

Afterthought this behavior not surprising at all but I think better to
document it somewhere (or even better disable ALTER PUBLICATION ... SET
(publish_via_partition_root) for any publication with existing subscriptions
because it will break things for sure).

After I look into pub/sub code - I feel it will be very complicated task to
make it work correctly.

--
Maxim