[xquery-talk] Re: The State of Native XML databases

John Snelson john.snelson at oracle.com
Tue Aug 21 00:20:19 PDT 2007

Ilya Sterin wrote:
>> Some type of schema can of course be useful in different scenarios, but
>> Ilya's suggestion that "ddl=xml schema" does not suit everyone.
> Yeah, if you are not looking at XML as a persistence.  You wouldn't
> work with a relational store without a DDL, be it SQL or any other way
> to define your schema.  Yes, there are many use cases for using xml in
> its semi-structured loose format, that's just not for persisting
> application state per say, rather message snippets, configs, etc...
> Again, you could also argue that MySQL was useful before InnoDB was
> introduced.

Unlike the relational data model, XML is (can be) a self descriptive 
format. This is why it is easy to use an XML database without a schema, 
whereas it is impossible with a relational database.

With the XML data model, you have built-in schema evolution 
capabilities. If you impose a schema (XML Schema or otherwise) on your 
XML database, you loose that ability - and have to re-implement it in a 
convoluted way if you need it back again.


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