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Re: xml schema, types and uniqueness/key constraints

• To: Christian Nentwich <christian@s...>
• Subject: Re: xml schema, types and uniqueness/key constraints
• From: "Chiusano Joseph" <chiusano_joseph@b...>
• Date: Thu, 11 Sep 2003 14:55:07 -0400
• Cc: xml-dev@l...
• Organization: Booz Allen Hamilton
• References: <61985897.20030911194428@s...>

The only way around this that comes to my mind is to add unique/key
constraints for every element that is of the pertinent datatypes (which
I'm sure you've already thought of). This is one downside of using
global datatypes.

Kind Regards,
Joe Chiusano
Booz | Allen | Hamilton

Christian Nentwich wrote:
> 
> All,
> 
> we are currently looking at where uniqueness and key constraints can
> be applied to our schema.
> 
> The problem is, the schema is semantically very rich, big on element
> reuse, and huge. As a consequence, most of the schema is expressed in
> terms of data types.
> 
> There are a few constraints that have to hold for all instances of those
> data types, for example, "elements of type A must reference existing elements
> of type B", but schema lets you express key/uniqueness only *per-element*,
> not *per-datatype*. This is probably prohibitive from a schema management
> perspective.
> 
> Is there any way around this, or a best practice approach to addressing
> this?
> 
> Christian
> 
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