Databases for Sutra and Medusa

I spent the past few days reviewing my opportunities to switch Medusa's backend DB and get the indexer handling more content types. The Sutra metadata idea requires a real DB, and while Medusa can use it, to work well, Medusa would really become the filesystem indexer. Another VFS search is needed to provide the features needed for both file and meta data queries. Seth's ideas look good, and they look so close to RDF semantics, that I think RDF should be the default means for both meta and file data to be indexed/imported. I think we need a query object/language suitable for applications and users. I've continued playing with complex search layouts, and I think I've got one for files. Because of the flexibility needed for meta queries, I leaning toward some means of query command line completion. I don't think Seth will agree, but users do need some search now. I'm still not 100% on how to fit My ideas of a meta db into Seth's. I've been reading some code to see how it could work. I don't want to create new tables, rather, I want a set a attributes and relations that fit comfortably within Seth's plans.