Probably you heard about Apache Cassanda or Cassandra DB, the noSQL database management system created by Facebook and used by Twitter.
Maybe is the distributed database with high performance and scalability that you were looking for. Are you afraid of use it? The choice would be easier if you know how to monitor it.
With the plugin available in the modules library, monitor Apache Cassandra with Pandora FMS is a child's play..
In the following article you have all the usefull information to use it.ARTICLEPLUGIN