Cassandra uses two kinds of keys:
- the Partition Keys is responsible for data distribution across nodes
- the Clustering Key is responsible for data sorting within a partition
A primary key is a combination of those to types. The vocabulary depends on the combination:
- simple primary key: only the partition key, composed of one column
- composite partition key: only the partition key, composed of multiple columns
- compound primary key: one partition key with one or more clustering keys.
- composite and compound primary key: a partition key composed of multiple columns and multiple clustering keys.