Aha! Re-reading your previous comment I understood what you meant. So Cassandra has a "logical" key that is the primary key, and the actual key from HBase-like

Aha! Re-reading your previous comment I understood what you meant. So Cassandra has a "logical" key that is the primary key, and the actual key from HBase-like DBs is derrived from cluster key and the primary key. So in essence it's "metric.timestamp" as a row key but only schema defined. Nice.