to_number question 2004-07-15 - By Jonathan Gennick
Thursday, July 15, 2004, 8:08:04 AM, Stephen.Lee@(protected) (Stephen.Lee@(protected)) 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@(protected)
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