There's a hypothetical question on the Apache Cassandra mailing list about potentially expanding Cassandra's storage to be pluggable, specifically using RocksDB.
RocksDB has a 3 clause BSD license (
https://github.com/facebook/rocksdb/blob/master/LICENSE ), and a patent
grant ( https://github.com/facebook/rocksdb/blob/master/PATENTS )
I know the 3 clause BSD license is fine, but is the wording of the patent grant problematic?