Features
Durability
Key Maps can be buffered or unbuffered. Buffered Key Maps (default) flushes writes every second by default.
Unbuffered key maps writes to disc before a put callsback.
Atomicity
You can perform atomic operations on one record.
Multiple stores
A database can have zero or more key-value stores, which Alfred calls key maps.
Streams
You can create javascript-function-based activity filter streams.
Append-only files
Underneath, key maps store data on append-only files, so you can safely rsync it.
Integrity check
Every record is checked for integrity on retrieval. An CRC is stored on the trailer of each record.
Replication
Can do master-slave replication.
Indexes. in memory
Indexes are stored in memory for fast search and sorting.