Presto is a fully distributed (MPP) SQL query engine that supports Cassandra: http://prestodb.io/docs/current/connector/cassandra.html

You can even join together data from Hive, Cassandra, MySQL, PostgreSQL, Kafka, etc., all in one query. We don't have a connector for Mongo yet, but contributions are welcome!

The Cassandra connector was actually an external contribution. We don't use it at Facebook.