Cassandra's timestamps can be specified by the client: it's possible to use any integer as your timestamp, such as Lamport timestamps, or even atomic distributed counters (possibly using Cassandra's own counters).
Vector clocks are still out, though.
Edit: Actually, you can't do Lamport timestamps because you can't query the current value of a timestamp.
Re-edit: That's wrong. I shouldn't believe any old blog I find. (I'm leaving it in the comment because it was quoted in a reply.)
Vector clocks are still out, though.
Edit: Actually, you can't do Lamport timestamps because you can't query the current value of a timestamp.
Re-edit: That's wrong. I shouldn't believe any old blog I find. (I'm leaving it in the comment because it was quoted in a reply.)