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   XQuery updates and unnormalized data (RE: [xml-dev] A standard approach

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At 11:19 AM 8/25/2003, Dare Obasanjo wrote:
>Ah, yes. The main problems with the hierarchical model are that it 
>encourages data redundancy which leads to problems during updates and 
>deletions. XQuery has dodged the bullet with solving this problem for now 
>since the DML work is slated for v-next. Of course, XQuery has bigger 
>problems to solve than that whenever DML gets around to being specced 
>given its dependency on W3C XML Schema as a type system.

You can have data redundancy with either XML or relational databases. If 
you do, there are problems with updates. Persistent stores of XML will need 
to normalize data to make consistent updates easy, or else people will have 
to maintain a lot more error-prone code for updates. Data modeling 
techniques for XML will become much more important with XQuery updates.

But this is not XML vs. relational, this is normalized vs. non-normalized. 
XQuery updates will not magically normalize non-normalized data. SQL 
updates don't either. Data modeling is a good thing, and normalized 
representations of data are the best for persistent stores that need to be 



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