Cassandra avoids some of the really visible issues by being AP instead of CP. Hbase hits them, but dodges a bit by only having row level consistency. They are

Cassandra avoids some of the really visible issues by being AP instead of CP. Hbase hits them, but dodges a bit by only having row level consistency. They are solving very different problems. The lack of vector clocks in Cassandra can lead to some very non-intuitive (possible wrong) behavior - check out their counter implementation for some rage on that. It's pretty well made though, and I think C*, Hbase and Postgres all have great uses (along with Redis, and a lot of others) Mongo tends to get things subtly wrong in ways that corrupt data, or that don't scale, and it gives up both A and C.