Re: slow count in window query - Mailing list pgsql-hackers

Hello

look on:
postgres=# explain select count(*) over () from x;                        QUERY PLAN
-------------------------------------------------------------WindowAgg  (cost=0.00..265.00 rows=10000 width=0)  ->  Seq
Scanon 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

regards
Pavel Stehule