Subject: Re: Testing by counting or positional predicate
From: Jeni Tennison <mail@xxxxxxxxxxxxxxxx>
Date: Thu, 11 Jan 2001 17:32:16 +0000
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Hi Mike,
Thanks very much again for the discussion/explanation!
> I'm reminded of something I used to teach in relational database
> courses: leave it to the optimizer, unless you're desperate. If
> you're desperate, make changes empirically, making one change at a
> time and measuring and recording the results; if a change makes no
> difference, undo it. Don't try to understand the query execution
> plan unless you're REALLY desperate!
I take your point and your example illustrates it very nicely. If
nothing else, though, discussing various ways of doing the same thing
hopefully keeps you optimiser implementers on your toes :)
Jeni
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Jeni Tennison
http://www.jenitennison.com/
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