Re: Really dumb planner decision

От: Tom Lane
Тема: Re: Really dumb planner decision
Дата: ,
Msg-id: 16192.1239889768@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: Really dumb planner decision  (Merlin Moncure)
Ответы: Re: Really dumb planner decision  ("Kevin Grittner")
Re: Really dumb planner decision  (Robert Haas)
Список: pgsql-performance

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Really dumb planner decision  (Matthew Wakeling, )
 Re: Really dumb planner decision  (Grzegorz Jaśkiewicz, )
  Re: Really dumb planner decision  (Matthew Wakeling, )
   Re: Really dumb planner decision  (Robert Haas, )
    Re: Really dumb planner decision  (Matthew Wakeling, )
     Re: Really dumb planner decision  (Merlin Moncure, )
      Re: Really dumb planner decision  (Tom Lane, )
       Re: Really dumb planner decision  ("Kevin Grittner", )
        Re: Really dumb planner decision  (Merlin Moncure, )
       Re: Really dumb planner decision  (Robert Haas, )
        Re: Really dumb planner decision  (Matthew Wakeling, )
         Re: Really dumb planner decision  (Tom Lane, )
 Re: Really dumb planner decision  (Grzegorz Jaśkiewicz, )
  Re: Really dumb planner decision  (Matthew Wakeling, )

Merlin Moncure <> writes:
> On Thu, Apr 16, 2009 at 8:05 AM, Matthew Wakeling <> wrote:
>> That solves the problem. So, a view is treated as a subquery then?

> no...the view is simply inlined into the query (think C macro) using
> the rules.  You just bumped into an arbitrary (and probably too low)
> limit into the number of tables the planner can look at in terms of
> optimizing certain types of plans.

Bear in mind that those limits exist to keep you from running into
exponentially increasing planning time when the size of a planning
problem gets big.  "Raise 'em to the moon" isn't really a sane strategy.
It might be that we could get away with raising them by one or two given
the general improvement in hardware since the values were last looked
at; but I'd be hesitant to push the defaults further than that.

            regards, tom lane


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