[xquery-talk] SPARQL to XQuery transformation

Rob Gonzalez rob.gonzalez at gmail.com
Wed Apr 29 04:07:08 PDT 2009

It's Turing-complete, so no, there is no inherent disadvantage to
being purely functional, but it does have the advantage that
computation over large amounts of data can be more easily
parallelized, which is a huge advantage for XQuery in database

To your other point: inferencing isn't done as part of SPARQL
syntactically; that's part of the underlying data model and query
resolution.  I see no obvious reason, though maybe one exists, why
inferencing can't be done on an XML infoset (which is a directed
graph) in the same way that it's done on RDF data (which is a directed
graph).  I think it would be interesting to try to use OWL to describe
XML (OWL isn't specifically about RDF; it's just about things) to
prove this out (indeed, the fact that RDF can be serialized as XML
makes me think this wouldn't even be that challenging an exercise).


On Tue, Apr 28, 2009 at 8:32 PM, David A. Lee <dlee at calldei.com> wrote:
> I don't believe its impossible either, but I was thinking, as a purely
> functional language (if that makes a difference?)
> Is there any set of computations that xquery couldn't theoretically execute,
> that say a procedural language could ?
> Michael Kay wrote:
> It might be *possible* to do in XQuery but its not a simple
> "translation" of one query language to another, it would take
> writing an inference engine in xquery.  quite a project.
> If you can write an interpreter for a query language then you can write a
> compiler for it. And compiling into XQuery is probably easier than compiling
> into machine code. So as far as I can see, it doesn't look intrinsically
> impossible at all.
> Michael Kay
> http://www.saxonica.com/
> _______________________________________________
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> --
> -----------------------------------------------------------
> David A. Lee
> dlee at calldei.com
> http://www.calldei.com
> _______________________________________________
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> http://x-query.com/mailman/listinfo/talk

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