Re: Unexpected query plan results

From: Anne Rosset
Subject: Re: Unexpected query plan results
Date: ,
Msg-id: 4A205A4A.5050406@collab.net
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In response to: Re: Unexpected query plan results  (Robert Haas)
Responses: Re: Unexpected query plan results  (Robert Haas)
List: pgsql-performance

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Unexpected query plan results  (Anne Rosset, )
 Re: Unexpected query plan results  ("Dave Dutcher", )
  Re: Unexpected query plan results  (Anne Rosset, )
   Re: Unexpected query plan results  ("Dave Dutcher", )
    Re: Unexpected query plan results  (Scott Mead, )
    Re: Unexpected query plan results  (Anne Rosset, )
     Re: Unexpected query plan results  (Robert Haas, )
 Re: Unexpected query plan results  (Robert Haas, )
  Re: Unexpected query plan results  (Anne Rosset, )
   Re: Unexpected query plan results  (Robert Haas, )
    Re: Unexpected query plan results  (Anne Rosset, )
     Re: Unexpected query plan results  (Robert Haas, )
      Re: Unexpected query plan results  (Anne Rosset, )
       Re: Unexpected query plan results  ("Dave Dutcher", )
        Re: Unexpected query plan results  (Anne Rosset, )
       Re: Unexpected query plan results  (Robert Haas, )
        Re: Unexpected query plan results  (Віталій Тимчишин, )
         Re: Unexpected query plan results  (Robert Haas, )
        Re: Unexpected query plan results  (Anne Rosset, )
         Re: Unexpected query plan results  (Robert Haas, )

Robert Haas wrote:

>On Thu, May 28, 2009 at 6:46 PM, Anne Rosset <> wrote:
>
>
>>                                                 ->  Index Scan using
>>item_pk on item  (cost=0.00..176865.31 rows=97498 width=88) (actual
>>time=117.304..2405.060 rows=71 loops=1)
>>                                                       Filter: ((NOT
>>is_deleted) AND ((folder_id)::text = 'tracker3641'::text))
>>
>>
>
>The fact that the estimated row count differs from the actual row
>count by a factor of more than 1000 is likely the root cause of your
>problem here.  You probably want to figure out why that's happening.
>How many rows are in that table and what value are you using for
>default_statistics_target?
>
>...Robert
>
>

The table has 468173 rows and the value for default_statistics_target is
750.
Anne


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