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

On Wed, Jan 13, 2021 at 2:53 PM Dilip Kumar <dilipbalaut(at)gmail(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?
> >
>
> Instead of doing this, I would expect that the RelationSyncCache entry
> should be removed when the relation is dropped from the publication.
> So if that is done then it will reload the publication and then it
> will not find that that relation as published and it will ignore the
> changes. But the patch doesn't seem to be exactly on that line. Am I
> missing something here?

IIUC, it's not possible to remove the cache entry inside
rel_sync_cache_publication_cb, because we don't receive the relid of
the alter publication .. dropped relation in the invalidation
callback. See the below comment,

/*
* There is no way to find which entry in our cache the hash belongs to so
* mark the whole cache as invalid.
*/
hash_seq_init(&status, RelationSyncCache);
while ((entry = (RelationSyncEntry *) hash_seq_search(&status)) != NULL)
entry->replicate_valid = false;

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