Subject Re: [Firebird-devel] Re: [IB-Architect] Re: triggers + plans
Author Helen Borrie
At 11:36 AM 22-05-02 +0200, Mirza wrote:
>Is it really possible for any optimizer to make (at least almost) perfect
>plan for every query?

Probably not; but at least you can influence the IB optimizer's "good hit"
rate by providing a well-designed, well-coordinated collection of indexes
for it to choose from. From observations over several years in support
lists, bad optimizer plans are the outcome of poor database design and lack
of consideration of contradictory indexing - typically, where a database
has been ported from Access or Paradox with its indexes simply replicated.

You've seen the comments: "If you're lucky, you'll get a good plan out of
the optimizer." Yep, it's true: and the better your design, the luckier
you get.


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