On Sun, Mar 05, 2017 at 08:23:08PM -0800, Jeff Janes wrote: > On Fri, Mar 3, 2017 at 4:44 AM, Dinesh Chandra 12108 <Dinesh.Chandra@xxxxxxxxxx> wrote: > > The below is the output for psql=> EXPLAIN ANALYZE SELECT DISTINCT > > feature_id FROM evidence.point p INNER JOIN evidence.observation_evidence > > oe ON p.feature_id = oe.evd_feature_id WHERE p.domain_class_id IN (11) AND > > (p.modification_time > '2015-05-10 00:06:56.056 IST' OR > > oe.modification_time > '2015-05-10 00:06:56.056 IST') ORDER BY feature_id > ... > > > -> Index Scan using point_domain_class_id_index on point p (cost=0.00..1483472.70 rows=1454751 width=16) (actual time=27.265..142101.1 59 rows=1607491 loops=1) > > Index Cond: (domain_class_id = 11) > > Why wouldn't this be using a bitmap scan rather than a regular index scan? > It seems like it should prefer the bitmap scan, unless the table is well > clustered on domain_class_id. In which case, why isn't it just faster? Could you send: SELECT * FROM pg_stats WHERE tablename='point' AND attname='domain_class_id' ; .. or if that's too verbose or you don't want to share the histogram or MCV list: SELECT correlation FROM pg_stats WHERE tablename='point' AND attname='domain_class_id' ; Justin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
