On Thu, Jun 10, 2010 at 12:34:07PM -0700, Anne Rosset wrote: > Jochen Erwied wrote: >> Thursday, June 10, 2010, 8:36:08 PM you wrote: >> >> >>> psrdb=# (SELECT >>> psrdb(# MAX(item_rank.rank) AS maxRank >>> psrdb(# FROM >>> psrdb(# item_rank item_rank >>> psrdb(# WHERE >>> psrdb(# item_rank.project_id='proj2783' >>> psrdb(# AND item_rank.pf_id IS NULL >>> psrdb(# >>> psrdb(# ) >>> psrdb-# ORDER BY >>> psrdb-# maxRank DESC; >>> >> >> Don't think it does really matter, but why do you sort a resultset >> consisting of only one row? >> >> > Sorry, I should have removed the ORDER by (the full query has a union). > So without the ORDER by, here are the results: > psrdb=# SELECT > psrdb-# MAX(item_rank.rank) AS maxRank > psrdb-# FROM > psrdb-# item_rank item_rank > psrdb-# WHERE > psrdb-# item_rank.pf_id='plan1408'; > maxrank > ------------- > 20504000000 > (1 row) > > Time: 1.516 ms > psrdb=# SELECT > psrdb-# MAX(item_rank.rank) AS maxRank > psrdb-# FROM > psrdb-# item_rank item_rank > psrdb-# WHERE > psrdb-# item_rank.project_id='proj2783' > psrdb-# AND item_rank.pf_id IS NULL; > maxrank > ------------- > 20200000000 > (1 row) > > Time: 13.177 ms > > Is there anything that can be done for the second one? > > Thanks, > Anne > What about an IS NULL index on pf_id? Regards, Ken -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
