> I can't think of any columnar DBs that are FOSS aside from Cloudera's Impala Cassandra isn't strictly a columnar store, but it has much the same properties.

> I can't think of any columnar DBs that are FOSS aside from Cloudera's Impala Cassandra isn't strictly a columnar store, but it has much the same properties. MonetDB. (O)RCFile. InfiniDB (which actually did go out of business, and is still available as open source). Druid. I'm sure I missed a bunch of others.