Re: Need to increase performance of a query - Mailing list pgsql-performance

From Anne Rosset
Subject Re: Need to increase performance of a query
Date
Msg-id 4C113E2F.6000305@collab.net
Whole thread Raw
In response to Need to increase performance of a query  (Anne Rosset <arosset@collab.net>)
Responses Re: Need to increase performance of a query  (Kenneth Marshall <ktm@rice.edu>)
Re: Need to increase performance of a query  (Jochen Erwied <jochen@pgsql-performance.erwied.eu>)
Re: Need to increase performance of a query  (Craig James <craig_james@emolecules.com>)
List pgsql-performance
Jochen Erwied wrote:
> Thursday, June 10, 2010, 8:36:08 PM you wrote:
>
>
>> psrdb=# (SELECT
>> psrdb(#        MAX(item_rank.rank) AS maxRank
>> psrdb(# FROM
>> psrdb(#        item_rank item_rank
>> psrdb(# WHERE
>> psrdb(#        item_rank.project_id='proj2783'
>> psrdb(#         AND item_rank.pf_id IS NULL
>> psrdb(#
>> psrdb(# )
>> psrdb-# ORDER BY
>> psrdb-# maxRank DESC;
>>
>
> Don't think it does really matter, but why do you sort a resultset
> consisting of only one row?
>
>
Sorry, I should have removed the ORDER by (the full query has a union).
So without the ORDER by, here are the results:
psrdb=# SELECT
psrdb-#        MAX(item_rank.rank) AS maxRank
psrdb-# FROM
psrdb-#        item_rank item_rank
psrdb-# WHERE
psrdb-#        item_rank.pf_id='plan1408';
   maxrank
-------------
 20504000000
(1 row)

Time: 1.516 ms
psrdb=# SELECT
psrdb-#        MAX(item_rank.rank) AS maxRank
psrdb-# FROM
psrdb-#        item_rank item_rank
psrdb-# WHERE
psrdb-#        item_rank.project_id='proj2783'
psrdb-#         AND item_rank.pf_id IS NULL;
   maxrank
-------------
 20200000000
(1 row)

Time: 13.177 ms

Is there anything that can be done for the second one?

Thanks,
Anne

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