Re: performance with query

От: Tom Lane
Тема: Re: performance with query
Дата: ,
Msg-id: 15037.1245353961@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: performance with query  ("Kevin Grittner")
Ответы: Re: performance with query  ("Kevin Grittner")
Список: pgsql-performance

Скрыть дерево обсуждения

performance with query  (Alberto Dalmaso, )
 Re: performance with query  (Joshua Tolley, )
 Re: performance with query  ("Kevin Grittner", )
 Re: performance with query  (Alberto Dalmaso, )
  Re: performance with query  (Matthew Wakeling, )
   Re: performance with query  (Alberto Dalmaso, )
    Re: performance with query  (Tom Lane, )
     Re: performance with query  (Alberto Dalmaso, )
      Re: performance with query  (Tom Lane, )
      Re: performance with query (OT)  ("Albe Laurenz", )
    Re: performance with query  ("Kevin Grittner", )
  Re: performance with query  ("Kevin Grittner", )
   Re: performance with query  (Alberto Dalmaso, )
    Re: performance with query  ("Kevin Grittner", )
    Re: performance with query  ("Kevin Grittner", )
     Re: performance with query  (Alberto Dalmaso, )
      Speeding up a query.  ("Hartman, Matthew", )
       Re: Speeding up a query.  (Anthony Presley, )
        Re: Speeding up a query.  ("Hartman, Matthew", )
       Re: Speeding up a query.  ("Albe Laurenz", )
        Re: Speeding up a query.  (Grzegorz Jaśkiewicz, )
       Re: Speeding up a query.  (Alberto Dalmaso, )
        Re: Speeding up a query.  ("Kevin Grittner", )
        Re: Speeding up a query.  (Tom Lane, )
       Re: Speeding up a query.  (Merlin Moncure, )
        Re: Speeding up a query.  ("Hartman, Matthew", )
       Re: Speeding up a query.  ("Hartman, Matthew", )
       Re: Speeding up a query.  (Simon Riggs, )
        Re: Speeding up a query.  ("Hartman, Matthew", )
 Re: performance with query  (Alberto Dalmaso, )
 Re: performance with query  (Alberto Dalmaso, )
  Re: performance with query  ("Kevin Grittner", )
   Re: performance with query  (Alberto Dalmaso, )
    Re: performance with query  ("Kevin Grittner", )
     Re: performance with query  (Alberto Dalmaso, )
      Re: performance with query  ("Kevin Grittner", )
       Re: performance with query  (Tom Lane, )
        Re: performance with query  ("Kevin Grittner", )

"Kevin Grittner" <> writes:
> With all the optimizer options on, and the from_collapse_limit and
> join_collapse_limit values both set to 100, run an EXPLAIN (no
> ANALYZE) on your big problem query.  Let us know how long the EXPLAIN
> runs.  If it gets any errors, copy and paste all available
> information.  (General descriptions aren't likely to get us very far.)
> Since EXPLAIN without ANALYZE only *plans* the query, but doesn't run
> it, it should not take long to do this.

One issue here is that with the collapse limits cranked up to more than
geqo_threshold, he's going to be coping with GEQO's partially-random
plan selection; so whatever he reports might or might not be especially
reflective of day-to-day results.  I'm tempted to ask that he also push
up geqo_threshold.  It's possible that that *will* send the planning
time to the moon; but it would certainly be worth trying, to find out
what plan is produced.

            regards, tom lane


В списке pgsql-performance по дате сообщения:

От: "Kevin Grittner"
Дата:
Сообщение: Re: select max() much slower than select min()
От: Kenneth Marshall
Дата:
Сообщение: Re: 8.4 COPY performance regression on Solaris