> First, i have no knowledge of anyone that have implemented full
> disjunctions(ever) aside
> from the theoretical works of my colleagues.
> With the exception of a corner case of it, that I believe was a simulation in
> 96.
> (A. Rajaman and J.D. Ullman Integrating information by outerjoins and
> full-disjunctions).
> I'd love to hear about any implementation out there (aside from my colleagues
> work, which
> is mine also: cohen,sagiv, kimelfeld,kanza)
I didn't mean to imply there was. It was the Rajaraman & Ullman paper
that got me interested in FD's and then I've looked at the "Computing
Full Disjunctions" paper by Kanza & Sagiv which gives a general
solution.
Obviously from the second paper it's clear that implementing full
disjunction (efficiently) is a non-trivial exercise.
> It can never be a binary operation since at the heart of the matter is that
> you need to take
> each subset of the relations and join them. i.e.:
...
> Usually binary operations allow for a bottom up computation approach, but FD
> is a TOP down approach
> (Galindo-Legaria, C. outerjoins as disjunctions).
Right, thanks for clarifying.
>From a data analysis perspective I would like to be able to look at
various subsets, eg. FD(A,B,C), FD(B,C,D), FD(A,B,C,D) etc and so this
just means that each subset has too be computed independantly. I can
live with that but wasn't sure if I had missed something.
In any case, the difficulty of implementing FD precludes me from
experimenting with it just yet.
Regards
Lee
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