If something sounds too-good-to-be-true, it probably is. I don't love Cassandra, but it's not because it's written on the JVM (full disclosure, we roll our own

If something sounds too-good-to-be-true, it probably is. I don't love Cassandra, but it's not because it's written on the JVM (full disclosure, we roll our own JVM key-value datastore https://github.com/liveramp/hank https://github.com/liveramp/hank). If your random-access keystore is limited by anything except network and disk latency, you have bigger problems.