creationix’s nstore at master – GitHub
A simple in-process key/value document store for node.js. nStore uses a safe append-only data format for quick inserts, updates, and deletes. Also a index of all documents and their exact location on the disk is stored in in memory for fast reads of any document. This append-only file format means that you can do online backups of the datastore using simple tools like rsync. The file is always in a consistent state.