From: Andreas Joseph Krogh <andreak@officenet.no>
To: pgsql-sql@postgresql.org
Subject: Re: Help with UNION query
Date: Sun, 4 Sep 2005 20:54:00 +0200
Message-ID: <200509042054.02993.andreak@officenet.no> (raw)
In-Reply-To: <200509042008.21080.andreak@officenet.no>
References: <200509041914.33245.andreak@officenet.no>
<200509042008.21080.andreak@officenet.no>
On Sunday 04 September 2005 20:08, Andreas Joseph Krogh wrote:
> Replying to my self...
Again...
I managed to "reduse" my query to the following:
SELECT gr.groupname FROM onp_group gr, onp_user u
WHERE gr.id IN
(
SELECT g.id FROM
onp_group g, onp_user_group ug
WHERE g.groupname = ug.groupname AND ug.username = u.username
UNION
SELECT gc.child_id FROM
onp_group_children gc, onp_group g, onp_user_group ug
WHERE gc.group_id = g.id AND g.groupname = ug.groupname AND ug.username =
u.username
)
AND u.username = 'andreak';
But "EXPLAIN ANALYZE" tells me it's about 8x slower than this one:
SELECT gr.groupname FROM onp_group gr WHERE gr.id IN(
SELECT g.id
from onp_group g, onp_user_group ug
where g.groupname = ug.groupname AND ug.username = 'andreak'
UNION
SELECT gc.child_id
FROM onp_group_children gc, onp_group g, onp_user_group ug
WHERE gc.group_id = g.id AND g.groupname = ug.groupname AND ug.username =
'andreak'
);
So, the question stands: any idea on how to rewrite the lower wuery to only
specify "ug.username='andreak'" once?
--
Andreas Joseph Krogh <andreak@officenet.no>
Senior Software Developer / Manager
gpg public_key: http://dev.officenet.no/~andreak/public_key.asc
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To: pgsql-sql@postgresql.org
Cc: andreak@officenet.no
Subject: Re: Help with UNION query
In-Reply-To: <200509042054.02993.andreak@officenet.no>
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