Re: What happens between end of explain analyze and end of query execution ?
От | Tom Lane |
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Тема | Re: What happens between end of explain analyze and end of query execution ? |
Дата | |
Msg-id | 5541.1365265641@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: What happens between end of explain analyze and end of query execution ? (Franck Routier <franck.routier@axege.com>) |
Ответы |
Re: What happens between end of explain analyze and end
of query execution ?
Re: What happens between end of explain analyze and end of query execution ? |
Список | pgsql-performance |
Franck Routier <franck.routier@axege.com> writes: > Le 05/04/2013 16:17, Tom Lane a �crit : >> What have you got the statistics targets set to in this database? > Ok, the problem definitely comes from the default_statistics_target > which is obviously too high on the database. Yeah, eqjoinsel() is O(N^2) in the lengths of the MCV lists, in the worst case where there's little overlap in the list memberships. The actual cost would depend a lot on the specific column datatypes. Not sure about your report that re-analyzing with the same stats target made a significant difference. It might have been a matter of chance variation in the sampled MCV list leading to more or fewer matches. regards, tom lane
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