A Cure for Madness 2004-08-29 - By Jonathan Gennick
Sunday, August 29, 2004, 5:29:08 PM, Wolfgang Breitling (breitliw@(protected)) wrote:
WB > That 's not what he says in the article. There he gives an "unequivocal no "
WB > to the question whether it is valid to rewrite the query.
Date does not say that optimization, including merging,
can 't happen. Optimization is fine. I 've never been opposed
even to merging, so long as it is done in a way that
preserves the "as if " results, meaning that the results
still must be "as if " the subquery had been materialized,
even though, in fact, it has not been. This is a reachable
goal.
What Date says in his article is that the results of the
optimization do not match the results that you get by
following the conceptual process described in the language
standard, and thus the optimization is flawed.
Best regards,
Jonathan Gennick --- Brighten the corner where you are
http://Gennick.com * 906.387.1698 * mailto:jonathan@(protected)
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