Wht the SEQ Scan ?
От | Glen Eustace |
---|---|
Тема | Wht the SEQ Scan ? |
Дата | |
Msg-id | 1032045701.22254.3.camel@agree-6 обсуждение исходный текст |
Ответы |
Re: Wht the SEQ Scan ?
|
Список | pgsql-general |
I know this is an FAQ, but each case seems to be different. I can not understand why the primary index on this table is not used. It was specifically created to make this query run quickly. admin=# \d client_usage Table "client_usage" Column | Type | Modifiers ----------+----------------------+----------- client | smallint | userid | character varying(8) | period | character(6) | resource | smallint | tstamp | date | zone | smallint | cnt | integer | vol | integer | Indexes: client_usage_indx1 admin=# \d client_usage_indx1 Index "client_usage_indx1" Column | Type --------+---------------------- client | smallint userid | character varying(8) tstamp | date btree admin=# vacuum verbose analyze client_usage; NOTICE: --Relation client_usage-- NOTICE: Pages 23101: Changed 0, Empty 0; Tup 2365648: Vac 0, Keep 0, UnUsed 0. Total CPU 0.57s/0.08u sec elapsed 30.01 sec. NOTICE: Analyzing client_usage VACUUM admin=# explain SELECT zone, tstamp, sum( vol ) admin-# FROM client_usage admin-# WHERE userid='events' and client=10143 and admin-# tstamp >= '1-1-2002' and tstamp < '1-1-2003' admin-# group by zone, tstamp; NOTICE: QUERY PLAN: Aggregate (cost=70418.33..70419.27 rows=13 width=10) -> Group (cost=70418.33..70418.96 rows=125 width=10) -> Sort (cost=70418.33..70418.33 rows=125 width=10) -> Seq Scan on client_usage (cost=0.00..70413.96 rows=125 width=10) EXPLAIN -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Glen and Rosanne Eustace, GodZone Internet Services, a division of AGRE Enterprises Ltd., P.O. Box 8020, Palmerston North, New Zealand 5301 Ph/Fax: +64 6 357 8168, Mob: +64 21 424 015
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