Doesn't this assume that both writers want their value for the column to win, instead of one of them possibly deciding that it shouldn't write it's value if one already exists for the field?
Correct. But, in that case vector clocks does not help you either [unless you are okay with both writers thinking they have "won" for an unbounded period of time]; what you really need is true linearizability: http://www.datastax.com/dev/blog/lightweight-transactions-in...
