[eschwartz]

If you directly manipulate the db, then it is up to you to make sure you don't break anything... I strongly encourage you to use the `calibredb` CLI backend, or if you need a lot of flexibility, using the calibre apis via `calibre-debug` python scripts. e.g.

def init_cache(library_path=None):
    if not library_path:
        from calibre.utils.config import prefs
        library_path=prefs['library_path']
    from calibre.db.backend import DB
    from calibre.db.cache import Cache
    backend = DB(library_path)
    cache = Cache(backend)
    cache.init()
    return cache

This grants you access to the functions described in API Documentation for the database interface