Re: Testing by counting or positional predicate

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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