For awhile, all the buzz about the future of databases was NoSQL systems. I recall hearing for awhile about how great Cassandra was and that Cassandra was basically an open-source equivalent to Google's BigTable. Everything I've read seems to indicate that Cassandra may be more trouble than its worth ( http://en.wikipedia.org/wiki/Apache_Cassandra#Prominent_users ).Who here has actually used Cassandra DB? Are you happy with it? Is there a better alternative if I'm concerning moving away from MySQL?