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Re: magic-sets
"magic-sets" is a way of transforming
queries into more efficient forms. It is
a key optimization technology. It is rather
new.
I have only very abstracted algorithm
descriptions of it at the moment: too abstracted
for me to figure out how to implement it, at present.
By far the easiest way to do the transformation is in
Prolog. Why: because the transformation
is pure logic and because XPath is based
on Datalog. A magic set transformation
will eliminate unproductive sub-queries
(mostly).
I have a very nice prolog<->
java compiler that can do the transformations
automatically, once I get a useable
prolog re-write program.
I program in Prolog just fine:
I just don't understand
the notation these technical papers
are using.
If you want to take a hack
at it I will send you the best document I
have on the subject. It should
be a relatively self-contained project
to implement. You don't have to do
it in Prolog: it would be even better if
you could figure out how to implement
"magic" in Java.
As slow as Java processing is, every
CPU cycle counts.
Best Wishes,
Ann Tecklenburg