On Wed, Apr 8, 2009 at 11:59 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Wed, Apr 8, 2009 at 10:33 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> The main point is that the planner will prefer a bitmap scan for any >>> query that's estimated to return more than quite a small number of rows. > >> That makes sense, but what about the nestloop-over-inner-indexscan case? > > What about it? The provided patch made no attempt to optimize that > case. > > Doing so might well be interesting, but it's not getting done for 8.4. > I think it would be quite an invasive patch --- it's hard to see how to > do it without explicit support at the nestloop join level, so that you > could pipeline the processing of multiple key values coming from the outer > side of the join.
OK, I think I'm now understanding your line of thinking. Thanks for the explanation. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
