2009/7/17 Pavel Stehule <pavel.steh...@gmail.com>: > Hello > > look on: > postgres=# explain select count(*) over () from x; > QUERY PLAN > ------------------------------------------------------------- > WindowAgg (cost=0.00..265.00 rows=10000 width=0) > -> Seq Scan on x (cost=0.00..140.00 rows=10000 width=0) > (2 rows) > > Time: 1,473 ms > postgres=# explain select count(*) over (order by a) from x; > QUERY PLAN > ------------------------------------------------------------------------ > WindowAgg (cost=0.00..556.25 rows=10000 width=4) > -> Index Scan using gg on x (cost=0.00..406.25 rows=10000 width=4) > (2 rows) > > but > query1: 160ms > query2: 72ms
Well, how about "select a from x order by a"? I wonder if index scan affects more than windowagg. -- Hitoshi Harada -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
