Re: Need to increase performance of a query

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