Re: Order by (for 15 rows) adds 30 seconds to query time

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От Matthew Wakeling
Тема Re: Order by (for 15 rows) adds 30 seconds to query time
Дата
Msg-id alpine.DEB.2.00.0912021104380.25000@aragorn.flymine.org
обсуждение исходный текст
Ответ на Re: Order by (for 15 rows) adds 30 seconds to query time  (Jean-Michel Pouré <jmpoure@free.fr>)
Ответы Re: Order by (for 15 rows) adds 30 seconds to query time  (Craig Ringer <craig@postnewspapers.com.au>)
Список pgsql-performance
Дерево обсуждения 
On Tue, 1 Dec 2009, Jean-Michel Pouré wrote:
> PostgreSQL query analyzer needs to run a couple of times before it can
> rewrite and optimize the query. Make sure demand_id, id and join IDs
> carry indexes.

Huh? At what point does the planner carry over previous plans and use them
to further optimise the query?

But perhaps the biggest factor here is calling a five table join a "pretty
simple query".

Matthew

--
 Prolog doesn't have enough parentheses. -- Computer Science Lecturer

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