On Tue, Nov 3, 2015 at 06:05:11PM +0000, Robert Haas wrote: > postgres_fdw: Add ORDER BY to some remote SQL queries. > > If the join problem's entire ORDER BY clause can be pushed to the > remote server, consider a path that adds this ORDER BY clause. If > use_remote_estimate is on, we cost this path using an additional > remote EXPLAIN. If not, we just estimate that the path costs 20% > more, which is intended to be large enough that we won't request a > remote sort when it's not helpful, but small enough that we'll have > the remote side do the sort when in doubt. In some cases, the remote > sort might actually be free, because the remote query plan might > happen to produce output that is ordered the way we need, but without > remote estimates we have no way of knowing that. > > It might also be useful to request sorted output from the remote side > if it enables an efficient merge join, but this patch doesn't attempt > to handle that case.
Does this complete FDW join pushdown? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Roman grave inscription + -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
