Re: [HACKERS] Hints proposal

От: Robert Treat
Тема: Re: [HACKERS] Hints proposal
Дата: ,
Msg-id: 200610172218.53194.xzilla@users.sourceforge.net
(см: обсуждение, исходный текст)
Ответ на: Hints proposal  ("Jim C. Nasby")
Список: pgsql-performance

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Hints proposal  ("Jim C. Nasby", )
 Re: Hints proposal  (Bruce Momjian, )
  Re: Hints proposal  (Heikki Linnakangas, )
   Re: Hints proposal  (Tom Lane, )
   Re: Hints proposal  ("Jim C. Nasby", )
 Re: Hints proposal  ("Joshua Marsh", )
  Re: Hints proposal  ("Bucky Jordan", )
   Re: Hints proposal  (Robert Treat, )
    Re: Hints proposal  (Tom Lane, )
     Re: Hints proposal  (Robert Treat, )
  Re: Hints proposal  ("Jim C. Nasby", )
 Re: Hints proposal  (Tom Lane, )
  Re: Hints proposal  ("Merlin Moncure", )
  Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
   Re: [HACKERS] Hints proposal  (Josh Berkus, )
    Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
     Re: [HACKERS] Hints proposal  (Josh Berkus, )
      Re: [HACKERS] Hints proposal  ("Bucky Jordan", )
       Re: [HACKERS] Hints proposal  (Alvaro Herrera, )
      Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
       Re: [HACKERS] Hints proposal  (Tom Lane, )
       Re: [HACKERS] Hints proposal  ("Bucky Jordan", )
        Re: Hints proposal  ("Craig A. James", )
         Re: Hints proposal  (, )
         Re: Hints proposal  (Mark Kirkwood, )
          Re: Hints proposal  (Csaba Nagy, )
           Re: Hints proposal  (Brian Hurt, )
            Re: Hints proposal  (Bruce Momjian, )
            Re: Hints proposal  (Shaun Thomas, )
           Re: Hints proposal  (Mark Kirkwood, )
       Re: [HACKERS] Hints proposal  (Josh Berkus, )
        Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
         Re: [HACKERS] Hints proposal  (Alvaro Herrera, )
         Re: [HACKERS] Hints proposal  (Tom Lane, )
      Re: [HACKERS] Hints proposal  (Gregory Stark, )
    Re: Hints proposal  ("Craig A. James", )
    Re: [HACKERS] Hints proposal  ("Zeugswetter Andreas ADI SD", )
  Re: Hints proposal  (Csaba Nagy, )
   Re: [HACKERS] Hints proposal  (Josh Berkus, )
    Re: [HACKERS] Hints proposal  (Csaba Nagy, )
   Re: [HACKERS] Hints proposal  (Tom Lane, )
 Re: Hints proposal  (Jeff Davis, )
  Re: Hints proposal  (Csaba Nagy, )
   Re: Hints proposal  (Jeff Davis, )
    Re: Hints proposal  (Arjen van der Meijden, )
     Re: Hints proposal  (Tom Lane, )
      Re: Hints proposal  (Jeff Davis, )
     Re: Hints proposal  (Richard Broersma Jr, )
     Re: Hints proposal  (Christopher Browne, )
  Re: Hints proposal  ("Jim C. Nasby", )
   Re: Hints proposal  (Jeff Davis, )
 Re: [HACKERS] Hints proposal  (Andrew Sullivan, )
 Re: [HACKERS] Hints proposal  (Robert Treat, )

On Friday 13 October 2006 12:46, Gregory Stark wrote:
> Josh Berkus <> writes:
> >> > I actually think the way to attack this issue is to discuss the kinds
> >> > of errors the planner makes, and what tweaks we could do to correct
> >> > them. Here's the ones I'm aware of:
> >> >
> >> > -- Incorrect selectivity of WHERE clause
> >> > -- Incorrect selectivity of JOIN
> >> > -- Wrong estimate of rows returned from SRF
> >> > -- Incorrect cost estimate for index use
> >> >
> >> > Can you think of any others?
>
>  -- Incorrect estimate for result of DISTINCT or GROUP BY.

Yeah, that one is bad.  I also ran into one the other day where the planner
did not seem to understand the distinctness of a columns values across table
partitions...

--
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL


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