My latest home project (yet to be announced) is using MongoDB for storage, which led me to write a couple of libraries you may be interested in if you use that kind of database. Keep reading for the details. MongoDB directory for Lucene MongoDB.Lucene is what you would expected given the name: a MongoDB backend for Lucene indexes. It’s a simple port of the standard FSDirectory using Mongo’s GridFS storage. I’m sure there’s a lot of room for improvement (performance, storage efficiency, lock reliability), but it’s working well enough for small applications.