ScyllaDB
ScyllaDB is an open-source distributed NoSQL column-oriented data store, designed to be compatible with Apache Cassandra. It supports the same CQL query language but is written in C++ instead of Java to increase raw performance and leverage modern multi-code servers self-tuning.
ScyllaDB is also a hybrid between a key-value and a column-oriented database. Rows are organized into tables. The first component of a primary key is a partition key, and rows clustered by the remaining columns of the key. Other columns may be indexed separately from the primary key.