I also use cassandra heavily. From what I read (so not confirmed) one problem is that it uses space inefficiently. Since I predefine the columns anyway, they m

I also use cassandra heavily. From what I read (so not confirmed) one problem is that it uses space inefficiently. Since I predefine the columns anyway, they might as well use an efficient storage instead of mongodb style kv-pairs. I am also not convinced of the partition key necessity (although it doesn't hurt either once you got it). Finally, since my application runs on the JVM, I'd actually like to see a direct integration / an API that allows me to skip the socket overhead and launch cassandra directly on start-up. The advantage is mainly memory (just need half of it) and latency although I agree this is more difficult to maintain in a distributed scenario.