AYASU Satoshi
--元のメッセージ--
送信者 : Michal Politowski
送信者: pgsql-general-ow...@postgresql.org
To: pgsql-general@postgresql.org
件名: [GENERAL] Why would a scan take so long?
送信: 2010/10/2 12:13 AM
EXPLAIN SELECT count(DISTINCT catalog.id) FROM catalog WHERE flag=
On Fri, Oct 1, 2010 at 9:13 AM, Michal Politowski wrote:
> EXPLAIN SELECT count(DISTINCT catalog.id) FROM catalog WHERE flag=false;
1: Try running explain analyze select ... here. It's far more informative.
2: select distinct is generally slower than using group by.
>
EXPLAIN SELECT count(DISTINCT catalog.id) FROM catalog WHERE flag=false;
QUERY PLAN
-
Aggregate (cost=1615927.27..1615927.28 rows=1 width=8)
-> Seq Scan on catalog (
