At last we have a candidate for the DB. After the Xesam dude (Mikkel Kamstrup Erlandsen) joined the team he took my last proposal of a new DB design and did his voodoo to end up with.
Again please forgive me for using UML class diagram tools for designing the DB.
Here you can read more and get into details. I will try to finish the implementation until monday leaving the current interface unharmed.
Xesam as described by their page is:
short for eXtEnsible Search And Metadata and is an umbrella project with the purpose of providing unified APIs and specs for desktop search- and metadata services. We are collaborating with several projects such as Tracker, Strigi, Beagle, Pinot, Recoll, and Nepomuk-KDE.
This will allow us to use annotation as tags, bookmarks,and custom comments. Also its a good preparation for a optional Tracker backend as well as co-operation with other FLOSS Projects involved with RDF semantics while still being a project of our own. I am worried however how it is going to scale. But I guess nothing that some indexing and tweaking wont fix.