Re: Bad Plan for Questionnaire-Type Query

From: Tom Lane
Subject: Re: Bad Plan for Questionnaire-Type Query
Date: ,
Msg-id: 18966.1241827710@sss.pgh.pa.us
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In response to: Re: Bad Plan for Questionnaire-Type Query  (David Blewett)
List: pgsql-performance

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Bad Plan for Questionnaire-Type Query  (David Blewett, )
 Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
  Re: Bad Plan for Questionnaire-Type Query  (Tom Lane, )
   Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
    Re: Bad Plan for Questionnaire-Type Query  (Tom Lane, )
     Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
      Re: Bad Plan for Questionnaire-Type Query  (Tom Lane, )
 Re: Bad Plan for Questionnaire-Type Query  (Tom Lane, )
  Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
   Re: Bad Plan for Questionnaire-Type Query  (Tom Lane, )
    Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
    Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
     Re: Bad Plan for Questionnaire-Type Query  (Tom Lane, )
      Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
       Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
        Re: Bad Plan for Questionnaire-Type Query  (Josh Berkus, )
         Re: Bad Plan for Questionnaire-Type Query  (David Blewett, )
          Re: Bad Plan for Questionnaire-Type Query  (Robert Haas, )

David Blewett <> writes:
> On Thu, May 7, 2009 at 6:44 PM, Tom Lane <> wrote:
>> Look into pg_stats for the rows concerning the columns used in the
>> query's WHERE and JOIN/ON clauses.

> Okay, here you go:
> http://rafb.net/p/20y8Oh72.html

I got some time to poke into this, but didn't get very far --- the
joins that seem to be the main problem involve
canvas_textresponse.submission_id which you didn't include stats for.

            regards, tom lane


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From: Tom Lane
Date:
Subject: Re: Bad Plan for Questionnaire-Type Query
From: Laurent Wandrebeck
Date:
Subject: Re: Slow select performance despite seemingly reasonable query plan