Re[2]: to_number question

From: Jonathan Gennick <jonathan_at_gennick.com>
Date: Thu, 15 Jul 2004 08:50:50 -0400
Message-ID: <84981230715.20040715085050@gennick.com>

Thursday, July 15, 2004, 8:08:04 AM, Stephen.Lee_at_DTAG.Com (Stephen.Lee_at_DTAG.Com) wrote:

SLDC> I believe the purpose of the subquery was to "request
SLDC> it". The function was being applied to data that was
SLDC> not in the subquery. If this is part of the laws of
SLDC> SQL processing, "then the law is an ass". I'm more
SLDC> inclined to say that this is a bug.

Stephen's original problem and Tanel's solution are fascinating. I can see where the optimizer might try and combine Stephen's main query and subquery into just one query. However, it seems to me that an optimization should *never* return different results from the original operation that is being optimized.

This begs the question of how the optimizer should decide whether it's safe to merge a subquery and main query. Clearly, the optimizer seems to have made the wrong call in the case of the query we've been talking about.

I wish I had more time to spend thinking about all this, but I've got to get to work for the day.

Best regards,

Jonathan Gennick --- Brighten the corner where you are http://Gennick.com * 906.387.1698 * mailto:jonathan@gennick.com

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Received on Thu Jul 15 2004 - 07:47:35 CDT