xml-dev - RE: Storage of XML documents & Learning from history

[Kay Michael <Michael.Kay@icl.com>]

> I problem I am looking at is how best to store XML documents, 
> an area I'm sure a lot of developers are hitting right now.

The principal decision is between fine-grained storage (in which the
document structure is known to the DBMS) and coarse-grained storage (in
which it isn't).

Fine-grained storage is necessary if you want to use DBMS queries to process
the information, but it is incredibly expensive, regardless of whether you
use a relational or an object DB. Our experience is that fine-grained
storage is very rarely necessary or cost-effective: just extract the few
pieces of information needed to do queries, store these in separate columns,
and hold the rest of the XML document as a blob.

If you do need fine-grained storage, use an object database; relational
storage of these structures will in general be grotesque. Even with an
object DB, consider storing both the fine-grained and the coarse-grained
views, so that you never have to reassemble the full document by finding all
its bits.

The old analogy here is that of taking your car to pieces every time you
want to park it overnight...

Mike Kay

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