On Tue, Aug 23, 2011 at 7:58 PM, Kevin Burton <bur...@spinn3r.com> wrote:
> I had a thread going the other day about vector clock memory usage and that > it is a series of (clock id, clock):ts and the ability to prune old entries > … I'm specifically curious here how often old entries are pruned. > > If you're storing small columns within cassandra. Say just an integer. > The vector clock overhead could easily use up far more data than is > actually in your database. > > However, if they are pruned, then this shouldn't really be a problem. > > How much memory is this wasting? > I think there is some confusion here– cassandra doesn't use vector clocks. -ryan > Thoughts? > > > Jonathan Ellis jbel...@gmail.com to user > show details Aug 19 (4 days ago) > 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 > > > -- > > Founder/CEO Spinn3r.com > > Location: *San Francisco, CA* > Skype: *burtonator* > > Skype-in: *(415) 871-0687* > >
