From: "Koen Antonissen" <koen@v3.com>
To: <pgsql-sql@postgresql.org>
Subject: Join performance
Date: Tue, 5 Dec 2000 10:42:09 +0100
Message-ID: <BBEPKLBOJENIHNEGNKLFGEMMCBAA.koen@v3.com>
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Hi there,

I'm having some problems with the performance on queries including a join.

for example:
SELECT members_data.pwd FROM emails,members_data WHERE emails.email =
'koen@v3.com' AND emails.uin = members_data.uin;

is a lot slower then extracting the join into 2 seperate queries like:

SELECT emails.uin FROM emails WHERE lower(emails.email) = 'koen@v3.com';

--and use the result in the next query ($db_result)

SELECT members_data.pwd FROM members_data WHERE members_data.uin =
$db_result;

Now the login routine is MUCH faster ;-) , but performance problems remain
when the the result is more than 1 record (Unlike a unique emailaddress...)

Is there anyone out there who has ideas how to write faster queries
including tablejoins?

I already tried Inner Join, Natural Join and Join On, wich didn't seem
affect the performance in any way...

Kind regards,
Koen Antonissen
koen@trilab.com
www.trilab.com