Re: How to optimize monstrous query, sorts instead of using index - Mailing list pgsql-performance

Is this 7.3.x?  Can we see explain analyze output for the query?

On Wed, 2003-06-25 at 07:46, Michael Mattox wrote:
> I've used indexes to speed up my queries but this query escapes me.  I'm
> curious if someone can suggest an index or a way to modify the query to use
> the index.  The query is:
>
> select ms.averageconnecttimex as ms_averageconnecttime, ms.averagedurationx
> as ms_averageduration, ms.datex as ms_date, ms.idx as ms_id,
> ms.statusstringx as ms_statusstring, ms.statusx as ms_status,
> msi.actualcontentx as msi_actualcontent, msi.connecttimex as
> msi_connecttime, msi.correctcontentx as msi_correctcontent, msi.datex as
> msi_date, msi.descriptionx as msi_description, msi.durationx as
> msi_duration, msi.errorcontentx as msi_errorcontent, msi.idx as msi_id,
> msi.monitorlocationx as msi_monitorlocation, msi.statusstringx as
> msi_statusstring, msi.statusx as msi_status from monitorstatusx ms,
> monitorstatusitemx msi where monitorx.idx =
> 'M-TEST_1444-TEST_00_10560561260561463219352' AND monitorx.jdoidx =
> ms.monitorx AND ms.datex >= '2003-06-20 08:57:21.36' AND ms.datex <=
> '2003-06-29 08:57:21.36' AND ms.jdoidx = monitorstatus_statusitemsx.jdoidx
> AND monitorstatus_statusitemsx.statusitemsx =
> monitorstatusitemlistd8ea58a5x.jdoidx AND
> monitorstatusitemlistd8ea58a5x.statusitemlistx = msi.jdoidx ORDER BY ms_date
> DESC;
>
> Here is the result of explain:
>
>  Sort  (cost=9498.85..9500.16 rows=525 width=788)
>    Sort Key: ms.datex
>    ->  Nested Loop  (cost=0.00..9475.15 rows=525 width=788)
>          ->  Nested Loop  (cost=0.00..7887.59 rows=525 width=123)
>                ->  Nested Loop  (cost=0.00..6300.03 rows=525 width=107)
>                      ->  Nested Loop  (cost=0.00..4712.02 rows=525 width=91)
>                            ->  Index Scan using monitorx_id_index on
> monitorx  (cost=0.00..5.37 rows=1 width=8)
>                                  Index Cond: (idx =
> 'M-TEST_1444-TEST_00_10560561260561463219352'::character varying)
>                            ->  Index Scan using monitorstatusxmonitori on
> monitorstatusx ms  (cost=0.00..4695.65 rows=880 width=83)
>                                  Index Cond: ("outer".jdoidx = ms.monitorx)
>                                  Filter: ((datex >= '2003-06-20
> 08:57:21.36'::timestamp without time zone) AND (datex <= '2003-06-29
> 08:57:21.36'::timestamp without time zone))
>                      ->  Index Scan using monitorstatus_stjdoidb742c9b3i on
> monitorstatus_statusitemsx  (cost=0.00..3.01 rows=1 width=16)
>                            Index Cond: ("outer".jdoidx =
> monitorstatus_statusitemsx.jdoidx)
>                ->  Index Scan using monitorstatusitejdoid7db0befci on
> monitorstatusitemlistd8ea58a5x  (cost=0.00..3.01 rows=1 width=16)
>                      Index Cond: ("outer".statusitemsx =
> monitorstatusitemlistd8ea58a5x.jdoidx)
>          ->  Index Scan using monitorstatusitemx_pkey on monitorstatusitemx
> msi  (cost=0.00..3.01 rows=1 width=665)
>                Index Cond: ("outer".statusitemlistx = msi.jdoidx)
> (17 rows)
>
> As you can see, it's doing a sort on ms.datex.  I created an index on the
> monitorstatusx (ms) table for the datex, but it doesn't use it.  Is it
> possible to create an index to prevent this sort?
>
> Thanks,
> Michael
>
>
> Michael Mattox
> cunparis@yahoo.fr / http://www.advweb.com/michael
>
>
>
>
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--
Rod Taylor <rbt@rbt.ca>

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