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At 03:56 AM 9/30/2003, Rick Jelliffe wrote:
>Oh dear. What about Usage Scenario 5 of the XML Schemas Requirements[1]?
> "Use schema to help query formulation and optimization.
>
> A query interface inspect XML schemas to guide a user in the
> formulation of queries.
> Any given database can emit a schema of itself to inform other
> systems what counts as
> legitimate and useful queries."
>
>And the design requirement that the datatypes must "define a type system
>that is adequate
>for import/export from database systems (e.g., relational, object,
><http://www.olapcouncil.org/>OLAP)"
Well, as you know, I agree with you. If XQuery were to design its own
optimal schema language, I doubt that it would have xsi:nil or key/keyrefs
- features specifically provided for the sake of future query systems. I
think it was unwise to try to guess what the query language might become
later on.
>Other good quote, showing the false economy of non-modularity in big specs:
>
>* XQuery's design influenced by XML Schema's provision of
> "a set of primitive types, a type-definition facility, and an
> inheritance mechanism...
> (and) the validation process... Nevertheless, members of the working group
> attempted to modularize the parts of the language that are related to type
> definition and validation, so that XQuery could potentially be used with
> an alternative schema language at some future time."
I think this is important.
Jonathan
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