Mr Stassen
The point I am making is that any query employing EXISTS/NOT EXISTS will try to use an Index on the referenced column
IF you decide to use a subquery at a later point in time the Index on the column would
STILL be employed when EXISTS/NOT EXISTS is used to reference a column which is Indexed-
Martin Gainty
From: Michael Stassen <[EMAIL PROTECTED]>
To: Martin Gainty <[EMAIL PROTECTED]>
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Subject: Re: In Statement Help
Date: Tue, 03 Aug 2004 10:26:29 -0400
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Martin Gainty wrote:
Andrew et al-
Keep in mind that when you use LIKE you will NOT use an index but you will use a full table scan instead.
Agreed.
Also instead of using IN EXISTS uses Indexes on the master table query..if you have master-heavy or parent-heavy query use EXISTS/NOT EXISTS vs IN/NOT IN
http://archives.postgresql.org/pgsql-performance/2002-12/msg00185.php
It's not clear to me how that post is relevant. First, I'm uncertain of its accuracy. (The author clearly does not understand LEFT JOINs.) Second, I'm not sure it applies to mysql. Third, it's about subqueries, but there were no subqueries in this thread.
HTH, Martin Gainty
Michael
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