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

Michael Kay mike at saxonica.com
Mon Aug 20 20:21:24 PDT 2007

> What do you guys use?  Again, I'm not saying that XML Schema 
> should be used, I was more looking into schema as a general 
> term, we need something to define the storage and constraints, right?

Actually, you don't. I happen to think that it's often very beneficial to
have a schema (or several...), but there's absolutely no inherent
requirement to do so. It's quite possible to store a random collection of
well-formed XML documents and query them.

Moreover, the notion of a schema is orthogonal to the notion of a collection
of documents. A product may associate one with the other, but it is by no
means essential.

> Our biggest issue with Oracle and XMLDB were the fact that 
> there is absolutely no transactional integrity outside of a 
> collection entry.
> Each write to a particular collection entry requires a lock 
> of the document stored.  

That's nothing to do with transactional integrity. The granularity of
locking doesn't affect integrity, it only affects throughput. 

It's true of course that a system that doesn't offer locking at a finer
granularity than the document level is unsuitable for the kind of "one big
document" database design you have chosen. So you either have to change your
design, or choose a different product. The fact that the product was
designed for a different usage scenario from yours doesn't make the product
bad, it just makes it unsuitable for your chosen approach.

Michael Kay

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