The problem with naive last write wins is that writes don't always arrive at each replica in the same order. So no, that's a non-starter.
Vector clocks are a series of (client id, clock) entries, and usually a timestamp so you can prune old entries. Obviously implementations can vary, but to pick a specific example, Voldemort [1] uses 2 bytes per client id, a variable number (at least one) of bytes for the clock, and 8 bytes for the timestamp. [1] https://github.com/voldemort/voldemort/blob/master/src/java/voldemort/versioning/VectorClock.java On Fri, Aug 19, 2011 at 7:41 PM, Kevin Burton <bur...@spinn3r.com> wrote: > I have a few questions which I can't seem to find answers to... > I know that the memory overhead of timestamps is 8 bytes per row/column. > What is the memory overhead of vector clocks? > Is it possible (at least in theory) to run without timestamps on your > values? I'm fine with last writer wins semantics and the memory overhead > here seems very high. > I understand that the timestamps might also be for repartitioning which adds > complexity. > Thanks! > > -- > > Founder/CEO Spinn3r.com > > Location: San Francisco, CA > Skype: burtonator > > Skype-in: (415) 871-0687 > -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of DataStax, the source for professional Cassandra support http://www.datastax.com
