It's not built-in, of course, but if you can live with the quirky API, LMDB as an embedded key-value store will be hard to beat in terms of speed. It can also d

It's not built-in, of course, but if you can live with the quirky API, LMDB as an embedded key-value store will be hard to beat in terms of speed. It can also do "one-writer, many-readers" and transactions.