Shouldn't Cassandra be using Lamport timestamps or even vector clocks there? Relying on timer and its resolution sounds strange for a database, especially a distributed one.
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.)
you can get the timestamp of each column back as part of a SELECT.
is that not enough?
They are wrong though. As HN submission illustrates, people want some order and eventual consistency, not a rule to select a single field during concurrent changes. And this is where a Lamport timestamp could help.