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Re: Testing by counting or positional predicate
- To: Kay Michael <Michael dot Kay at icl dot com>
- Subject: Re: [xsl] Testing by counting or positional predicate
- From: Jeni Tennison <mail at jenitennison dot com>
- Date: Thu, 11 Jan 2001 17:32:16 +0000
- CC: "'xsl-list at lists dot mulberrytech dot com'" <xsl-list at lists dot mulberrytech dot com>
- Organization: Jeni Tennison Consulting Ltd
- References: <9008AF5250E3D411AE57009027CA88E30FCE9F@WWMESSD048>
- Reply-To: xsl-list at lists dot mulberrytech dot com
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
---
Jeni Tennison
http://www.jenitennison.com/
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