How to store XDI as key/value pairs

I spent some time trying to figure out how one would store an XDI graph in a key/value pair based datastore (e.g. Berkely DB), which is probably much more efficient than anything else.

The main requirement is that all basic operations on the XDI graph be possible without any trouble.

Here is how I would do it, feel free to comment if you have time:
http://wiki.oasis-open.org/xdi/XdiAsKeyValuePairs

Markus