Re: Performance problems with 9.2.15

От: Tom Lane
Тема: Re: Performance problems with 9.2.15
Дата: ,
Msg-id: 32524.1464356784@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Performance problems with 9.2.15  (Johan Fredriksson)
Ответы: Re: Performance problems with 9.2.15  (Johan Fredriksson)
Re: Performance problems with 9.2.15  (Johan Fredriksson)
Список: pgsql-performance

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Performance problems with 9.2.15  (Johan Fredriksson, )
 Re: Performance problems with 9.2.15  (Tom Lane, )
  Re: Performance problems with 9.2.15  (Johan Fredriksson, )
   Re: Performance problems with 9.2.15  (Steve Crawford, )
  Re: Performance problems with 9.2.15  (Johan Fredriksson, )
   Re: Performance problems with 9.2.15  (Johan Fredriksson, )
    Re: Performance problems with 9.2.15  (Johan Fredriksson, )
     Re: Performance problems with 9.2.15  (Claudio Freire, )
      Re: Performance problems with 9.2.15  ("David G. Johnston", )
       Re: Performance problems with 9.2.15  (Claudio Freire, )
        Re: Performance problems with 9.2.15  (Johan Fredriksson, )
         Re: Performance problems with 9.2.15  (Johan Fredriksson, )
          Re: Performance problems with 9.2.15  (Mark Kirkwood, )
           Re: Performance problems with 9.2.15  (Johan Fredriksson, )

Johan Fredriksson <> writes:
> I am just about to upgrade from PostgreSQL 8.4.20 to 9.2.15, but I'v run
> into some huge performance issues.

The rowcount estimates from 9.2 seem greatly different from the 8.4 plan.
Did you remember to ANALYZE all the tables after migrating?  Maybe there
were some table-specific statistics targets that you forgot to transfer
over?  In any case, the 9.2 plan looks like garbage-in-garbage-out to
me :-( ... without estimates at least a little closer to reality, the
planner is unlikely to do anything very sane.

(BTW, I wonder why you are moving only to 9.2 and not something more
recent.)

            regards, tom lane



В списке pgsql-performance по дате сообщения:

От: Jake Magner
Дата:
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От: Tom Lane
Дата:
Сообщение: Re: Planner chooses slow index heap scan despite accurate row estimates