So from the Lucene perspective, the idea of a filesystem is pretty baked into the format. However, there's also the idea of a Codec which takes the logical dat

So from the Lucene perspective, the idea of a filesystem is pretty baked into the format. However, there's also the idea of a Codec which takes the logical data structures and translates to/from the filesystem. If you made a Codec that ignored the filesystem and just interacted with FDB, then that could work. You can already tune segment sizes (a segment is a self-contained index over a subset of documents). I'd assume that the right thing to do for a first attempt is to use a Codec to write each term's entire posting list for that one segment to a single FDB key (doing similar things for the many auxiliary data structures). If it gets too big, then you should have tuned max segment size to be smaller. Do some sort of caching on the hot spots. If anyone has any serious interest in trying this, my email is in my profile to discuss further.