Re: Unexpected query plan results

From: Anne Rosset <arosset(at)collab(dot)net>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Unexpected query plan results
Date: 2009-05-29 21:57:30
Message-ID: 4A205A4A.5050406@collab.net
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Robert Haas wrote:

>On Thu, May 28, 2009 at 6:46 PM, Anne Rosset <arosset(at)collab(dot)net> 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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