CouchDB Implements a Fundamental Algorithm : Daytime Running Lights

CouchDB Implements a Fundamental Algorithm : Daytime Running Lights: "To get to the core of how CouchDB provides these properties in a lockless way requires understanding the append-only file format, but I'll give you the basic picture: Each db file has a single writer process and multiple reader processes. Readers can proceed independently of the writer, getting a consistent snapshot of the data, even as changes are being made."