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At 10:12 AM 5/4/2002 -0700, Dare Obasanjo wrote:
>The bottom line is that any XML database product that
>supports XQuery and W3C XML schema plus an update
>capability will have to support post-update validation
>because the XQuery and W3C XML Schema "type" systems
>leave the door open for too many things to be dynamic.
>
>
>By the way here are some quotes from the Formal
>Semantics document which point out what I mean by
>validation vs. type system
[ !!! SNIP !!!]
>Especially with regards to restriction facets, there
>simply is no way for this to be implemented without
>something akin to post-update validation. Identity
>constraints as well. In fact, when I think about even
>making sure that the results of an update do not
>result in an invalid content model for an element in
>the document is pretty much another validation issue
>not a type one.
Static analysis is not an all-or-nothing thing. Relational databases do not
use static analysis for constraints on values, but static analysis is
important for relational databases.
Restriction facets are generally constraints on values.
Jonathan
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