On Thu, Nov 12, 2015 at 12:54 AM, Etsuro Fujita <fujita.ets...@lab.ntt.co.jp> wrote: > Really? I think there would be not a little burden on an FDW author; when > postgres_fdw delegates to the subplan to the remote server, for example, it > would need to create a remote join query by looking at tuples possibly > fetched and stored in estate->es_epqTuple[], send the query and receive the > result during the callback routine. Furthermore, what I'm most concerned > about is that wouldn't be efficient. So, my question about that approach is > whether FDWs really do some thing like that during the callback routine, > instead of performing a secondary join plan locally. As I said before, I > know that KaiGai-san considers that that approach would be useful for custom > joins. But I see zero evidence that there is a good use-case for an FDW.
It could do that. But it could also just invoke a subplan as you are proposing. Or at least, I think we should set it up so that such a thing is possible. In which case I don't see the problem. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
