Re: Sort
От | Mitch Vincent |
---|---|
Тема | Re: Sort |
Дата | |
Msg-id | 00aa01bff344$41016780$4100000a@doot обсуждение исходный текст |
Ответ на | Sort ("Nathan Barnett" <nbarnett@cellularphones.com>) |
Список | pgsql-general |
Show the query and maybe someone could help :-) ----- Original Message ----- From: "Nathan Barnett" <nbarnett@cellularphones.com> To: <pgsql-general@postgresql.org> Sent: Friday, July 21, 2000 2:33 PM Subject: [GENERAL] Sort > I'm currently using v7.0.2 of PostgreSQL. > > I have a query that performs a group by on three columns. The EXPLAIN of > the query is as follows: > > Aggregate (cost=4116.05..4125.47 rows=94 width=24) > -> Group (cost=4116.05..4123.12 rows=942 width=24) > -> Sort (cost=4116.05..4116.05 rows=942 width=24) > -> Nested Loop (cost=0.00..4069.52 rows=942 width=24) > -> Seq Scan on click (cost=0.00..15.42 rows=942 > width=8) > -> Index Scan using impression_pkey on impression > (cost=0.00..4.29 rows=1 width=16) > > I need to speed up this query. I have already created an index on the three > columns query_idx(columna, columnb,columnc). Is there some other index that > I could add which would speed up the query. There is a high frequency in > the table of each group. Each group probably makes up 10% of the table. > Does this force a sequence scan when sorting and grouping? Basically just > looking for suggestions. > > > ---------------- > Nathan Barnett > >
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