Re: benchmarking the query planner

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От Alvaro Herrera
Тема Re: benchmarking the query planner
Дата
Msg-id 20081212170023.GE3806@alvh.no-ip.org
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Ответ на Re: benchmarking the query planner  ("Robert Haas" <robertmhaas@gmail.com>)
Ответы Re: benchmarking the query planner  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: benchmarking the query planner  (Bruce Momjian <bruce@momjian.us>)
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Robert Haas escribió:
> > Which raises the issue, if we could get better statistics by passing
> > the whole table, why not do that when VACUUM ANALYZE is run?
> 
> I think the reason is "because the next autovacuum would undo it".

Is there any way to "merge" the statistics?  i.e. if a full table scan
is done to compute precise statistics, and later a regular analyze scan
is done, then perhaps instead of clobbering the previous stats, you
merge them with the new ones, thus not completely losing those previous
ones.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support


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