Re: Functionscan estimates

From: Michael Fuhr
Subject: Re: Functionscan estimates
Date: ,
Msg-id: 20050408223820.GA17450@winnie.fuhr.org
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In response to: Functionscan estimates  (Josh Berkus)
Responses: Re: Functionscan estimates  (Alvaro Herrera)
List: pgsql-performance

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Functionscan estimates  (Josh Berkus, )
 Re: Functionscan estimates  (Michael Fuhr, )
  Re: Functionscan estimates  (Alvaro Herrera, )
   Re: Functionscan estimates  (Josh Berkus, )
    Re: Functionscan estimates  (Alvaro Herrera, )
     Re: Functionscan estimates  (Tom Lane, )
      Re: Functionscan estimates  (PFC, )
      Re: Functionscan estimates  ("Jim C. Nasby", )
       Re: Functionscan estimates  (Tom Lane, )
        Re: Functionscan estimates  (Neil Conway, )
         Re: Functionscan estimates  (Josh Berkus, )
      Re: Functionscan estimates  (Neil Conway, )
    Re: Functionscan estimates  (PFC, )

On Fri, Apr 08, 2005 at 03:15:50PM -0700, Josh Berkus wrote:
>
> I'm wondering if it might be useful to be able to add estimated selectivity to
> a function definition for purposes of query estimation.  Currently function
> scans automatically return a flat default 1000 estimated rows.   It seems
> like the DBA ought to be able to ALTER FUNCTION and give it a row estimate
> for planning purposes.

About a month ago I mentioned that I'd find that useful.  In a
followup, Christopher Kings-Lynne brought up the idea of a GUC
variable that could give hints about the expected row count.

http://archives.postgresql.org/pgsql-hackers/2005-03/msg00146.php
http://archives.postgresql.org/pgsql-hackers/2005-03/msg00153.php

--
Michael Fuhr
http://www.fuhr.org/~mfuhr/


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