Composite Partition Key

The primary key is a crucial component of the Apache Cassandra data model, serving two essential functions:

1. It ensures the uniqueness of each record.

2. It determines the record’s placement within the cluster.

In Cassandra, a table’s primary key consists of one or more partition keys and zero or more clustering columns, with the partition key(s) always listed first in the primary key definition.

In Apache Cassandra, a table’s primary key cannot be altered. Modifying the primary key is not allowed as it determines how table data is distributed across the cluster and how it is stored on disk.