Point of clustring key

Question

I have been reading articles about Apache Cassandra lately and I pretty perceive partitioning key and clustering key and their difference. But I wonder what is the point of clustering key? Does it help to retrieve data faster?

Answer 1

Clustering key provides uniqueness of the rows inside partition (by combining values of all clustering columns), and organize data in sorted order. Plus when you're retrieving multiple related values, then reading them from the same partition could be faster than retrieving multiple partition keys as you're performing that operation inside one or more replicas that are responsible for given partition.