>-Original Message-
>From: vegiv...@gmail.com [mailto:vegiv...@gmail.com] On Behalf Of Johan De
>Meersman
>Sent: Thursday, June 03, 2010 6:52 AM
>To: je...@gii.co.jp
>Cc: mysql@lists.mysql.com
>Subject: Re: Slow when using sub-query
>
>The short answer is that
The short answer is that the optimizer is amazingly stupid about subqueries,
and it assumes that they are dependent even when they're not - that subquery
gets executed for every row in your main query.
The fastest way to do this, would probably be to run your subquery, have
your code assemble the
I've heard that sub-queries aren't well-optimized, but this case seems
ridiculous.
First, a little setup:
SELECT pub_id FROM pub WHERE pub_code = 'GD' INTO @P;
=== Inner Query by Itself ===
us-gii >SELECT prod_pub_prod_id FROM prod
-> WHERE pub_id = @P
-> AND prod_discont = 0
-> GR
