A couple of days coding around RocksDB or LMDB would allow you to write one yourself. I'm not mentioning LevelDB on purpose because it doesn't allow you to hav

A couple of days coding around RocksDB or LMDB would allow you to write one yourself. I'm not mentioning LevelDB on purpose because it doesn't allow you to have several processes writing and reading to the store at the same time, which really sucks if you want to separate ingestion and projection services, for example.