On 2017/03/14 6:31, Corey Huinker wrote: > On Mon, Mar 13, 2017 at 1:06 AM, Corey Huinker <corey.huin...@gmail.com> > wrote: > >> >>> I think it will, because Append itself has been made async-capable by one >>> of the patches and UNION ALL uses Append. But as mentioned above, only >>> the postgres_fdw foreign tables will be able to utilize this for now. >>> >>> >> Ok, I'll re-run my test from a few weeks back and see if anything has >> changed. >> > > > I'm not able to discern any difference in plan between a 9.6 instance and > this patch. > > The basic outline of my test is: > > EXPLAIN ANALYZE > SELECT c1, c2, ..., cN FROM tab1 WHERE date = '1 day ago' > UNION ALL > SELECT c1, c2, ..., cN FROM tab2 WHERE date = '2 days ago' > UNION ALL > SELECT c1, c2, ..., cN FROM tab3 WHERE date = '3 days ago' > UNION ALL > SELECT c1, c2, ..., cN FROM tab4 WHERE date = '4 days ago' > > > I've tried this test where tab1 through tab4 all are the same postgres_fdw > foreign table. > I've tried this test where tab1 through tab4 all are different foreign > tables pointing to the same remote table sharing a the same server > definition. > I've tried this test where tab1 through tab4 all are different foreign > tables pointing each with it's own foreign server definition, all of which > happen to point to the same remote cluster. > > Are there some postgresql.conf settings I should set to get a decent test?
I don't think the plan itself will change as a result of applying this patch. You might however be able to observe some performance improvement. Thanks, Amit -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers