What Is Cluster Key

A clustering key is a subset of columns in a table (or expressions on a table) that are explicitly designated to co-locate the data in the table in the same micro-partitions.

What is cluster key in Cassandra?

Clustering keys are responsible for sorting data within a partition. Each primary key column after the partition key is considered a clustering key. In the crossfit_gyms_by_location example, country_code is the partition key; state_province, city, and gym_name are the clustering keys.

Is clustering key required in Cassandra?

So each query needs to have them specified. Without which Cassandra won’t know which node to search for. The clustering keys (columns, which are optional) help in further narrowing your query search after Cassandra finds out the specific node(and it’s replicas) responsible for that specific Partition key.