From: Anne Rosset <arosset@collab.net>
To: Jochen Erwied <jochen@pgsql-performance.erwied.eu>
Cc: pgsql-performance@postgresql.org
Subject: Re: Need to increase performance of a query
Date: Thu, 10 Jun 2010 12:34:07 -0700
Message-ID: <4C113E2F.6000305@collab.net> (raw)
In-Reply-To: <98414706.20100610212211@erwied.eu>
References: <4C1125F0.8090101@collab.net>
<4C112B19.6080908@krogh.cc>
<4C113098.5040105@collab.net>
<98414706.20100610212211@erwied.eu>
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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To: pgsql-performance@postgresql.org
Cc: arosset@collab.net, jochen@pgsql-performance.erwied.eu
Subject: Re: Need to increase performance of a query
In-Reply-To: <4C113E2F.6000305@collab.net>
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