[Versa] Issue 3

[Uche Ogbuji]

On Fri, 2005-08-12 at 09:25 -0600, Michael Olson wrote:
> >>> So, 1 and 2 we have already.  3 would require promoting statements to
> >>> first class Versa datatypes (which I think would have benefits - but
> >>> how would statement data types work with the other data types for
> >>> conversion to and from, etc..).  4 would just be an extension of the
> >>> traversal syntax and would solve the original problem.
> >>>
> >>
> >> What if statement datatypes were the results of a traversal?  Then
> >> different functions to convert to the different pieces of the
> >> statements.
> >>
> >> subject(* - rdf:type -> rdf:Property)   would be the set of all
> >> resources in the system that are properties.
> >
> > I thought of this, but I'm vexed by the question of whether those
> > subexpressions should all be match lists, or whether object should  
> > still
> > be a functional predicate.  You take the former approach in your
> > example.
> >
> > Either way, again, it's a backward incompatible change, and calls for
> > 2.0.
> >
> 
> What I don't like about this approach is that if all you want is the  
> objects, conceptually, and until we get a good optimizer, you get the  
> statements (lots of data) just to trim it back to objects.....

Well, there is a lot in Versa which needs a decent optimizer, which is
why I wrote one for 4RDF.  I could fairly easily extend the optimizer to
this case.

The requires-good-optimizer characteristic is pretty standard in query
language.  The more expressive the language, the more work needs to be
done in an optimizer.


-- 
Uche Ogbuji                               Fourthought, Inc.
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