Re: Unexpected query plan results - Mailing list pgsql-performance

From Robert Haas
Subject Re: Unexpected query plan results
Date
Msg-id 603c8f070906011324xf8ed743rfaf89ff21ddbf164@mail.gmail.com
Whole thread Raw
In response to Re: Unexpected query plan results  (Anne Rosset <arosset@collab.net>)
Responses Re: Unexpected query plan results  (Anne Rosset <arosset@collab.net>)
List pgsql-performance
On Mon, Jun 1, 2009 at 2:14 PM, Anne Rosset <arosset@collab.net> wrote:
>>> The table has 468173 rows and the value for default_statistics_target is
>>> 750.
>>> Anne
> Hi Robert,
> we did a vacuum analyze and the results are the same.
> Here are the results of the queries :
>
> SELECT SUM(1) FROM item WHERE is_deleted = 'f'; sum --------- 1824592 (1
> row)
> SELECT SUM(1) FROM item WHERE folder_id = 'tracker3641
> </sf/sfmain/do/go/tracker3641?returnUrlKey=1243878161701>'; sum --------
> 122412 (1 row)
> SELECT SUM(1) FROM item WHERE folder_id = 'tracker3641
> </sf/sfmain/do/go/tracker3641?returnUrlKey=1243878161701>' AND is_deleted =
> 'f'; sum ----- 71 (1 row)
> SELECT SUM(1) FROM item WHERE folder_id = 'tracker3641
> </sf/sfmain/do/go/tracker3641?returnUrlKey=1243878161701>' AND is_deleted =
> 't'; sum -------- 122341 (1 row)

Something's not right here.  If the whole table has only 468173 rows,
you can't have 1.8 million deleted rows where is_deleted = false.

...Robert

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