CAP

Tip: Usually analysed in the context of a master with its replicas. Consider reads and writes sent to the replicas.

Theorem

Consistency

Every read returns the most recent right, or an error.

Eventual Consistency

• Low latency but stale data

Strong Consistency

• High latency but latest write

Availability

Every requests receives a non-error response, without the guarantee that it contains the most recent write.

Partition Tolerance

System operates despite aribitrary number of messages droppped by network.