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RE: Query decomposition [was: What niche is XQuery targeting?]

• To: "'Michael Kay'" <mike@s...>,"'XML Developers List'" <xml-dev@l...>
• Subject: RE: Query decomposition [was: What niche is XQuery targeting?]
• From: "Peter Coppens" <pgp.coppens@p...>
• Date: Wed, 15 Dec 2004 11:04:36 +0100
• In-reply-to: <E1CeVMP-0005r9-00@u...>
• Thread-index: AcTia1BPxPxNLyjjQZiWVI73DUa2KwAGQvhQAAHU7TA=

> Decomposing relational queries to address multiple relational 
> data sources
> is by now a well-understood problem, but it only works if 
> each data source
> can be modelled in terms of a relational view. If the actual 
> data is the
> archive of an email mailing list, modelling it as a collection of XML
> documents is probably going to be much easier. I see no 
> reason why the same
> query decomposition techniques shouldn't work with XQuery as 
> with SQL, but
> the technique will be far more powerful simply because XML is a richer
> model.
At least one extra problem comes from the fact that XML is a much richer
data model than what is potentially offered by the underlying (relational)
data store - that is why it is so interesting as a conceptual platform for
integration of course . Because of this richer model, any XML processing
environment defines operations on its data model that might not be obvious
to translate to whatever processing alternative you have on the underlying
data store. I am afraid there is no magic to be expected here - somewhere
somehow the nuts and bolds will always stick out - either the user has to
manually code around the 'mismatch' or the integration 'system' will show
awkward inconsistencies, either in features or performance characteristics.

Or at least...that is what I think today.

Peter

• References:
  • RE: Query decomposition [was: What niche is XQuery targeting?]
    • From: "Michael Kay" <mike@s...>

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