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RE: XQuery -- Reinventing the Wheel?

• From: Michael Rys <mrys@m...>
• To: 'Bob Kline' <bkline@r...>, Evan Lenz <elenz@x...>
• Date: Wed, 21 Feb 2001 18:50:32 -0800

XPath 1.0 does not, XPath 2.0 or XSLT 2.0 may (or whatever the wording in
their requirement document is). The document() function is really not a
replacement since it does not scale well to 10'000s of XML
fragments/documents.

Evan, you actually left out an important result of your simplistic formula,
by elminiating the template rules and stratifying some of the semantics,
XQuery aims to become better optimizable for people that care about
performance and scalability. It also will become strongly typed if complex
and simple type is available, which XSLT 2.0 will not be.

Don't get me wrong: For data-driven transformations XSLT's rule driven
approach is great. The only problem is that have not yet seen a high
performance/highly scalable engine for rule-based engines (and projects such
as the ICSI project on a highly-parallel rule inference engine don't count,
they normally test the boundary of hardware (cost)) that can compare to a
algebra-based query engine with optimizer.

So for acceptance of a query language in the data community, a query
language a la XQuery will find larger acceptance and more efficient
implementations.

Hope this helps to clarify this at least a bit.

Best regards
Michael, member of the XML Query WG, but speaking strictly for himself.

PS: Evan, are you at DevCon London? Feel free to give me a call if you want
to discuss this F2F.


> -----Original Message-----
> From: Bob Kline [mailto:bkline@r...]
> Sent: Wednesday, February 21, 2001 3:46 PM
> To: Evan Lenz
> Cc: xml-dev@l...
> Subject: Re: XQuery -- Reinventing the Wheel?
> 
> 
> On Wed, 21 Feb 2001, Evan Lenz wrote:
> 
> > Simplistically,
> > 
> > XQuery = XSLT - templateRules - nonAbbreviatedXPathAxes
> > 
> > Apart from datatypes, which XPath currently does not support (but
> > apparently will), the areas where XQuery purportedly introduces new
> > functionality are matters of convenience.
> 
> I have been given to understand that XQuery supports searches across a
> collection of XML documents and XPath does not.  Are you saying that
> this understanding is incorrect?
> 
> -- 
> Bob Kline
> mailto:bkline@r...
> http://www.rksystems.com
> 
> 
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