Cassandra Practice Test

Are partition key columns optional if clustering columns are present?

1. Yes, they are optional

2. No, they are mandatory

3. It depends on the use case

4. No, they can be substituted

The correct answer is: No, they are mandatory

In a Cassandra database, the architecture relies on a specified data model that uses partition keys and clustering columns to organize and access data efficiently. The partition key is a fundamental component of Cassandra's data model, as it determines how data is distributed across different nodes in the cluster. Partition keys are mandatory because they are responsible for defining how data is partitioned and stored; without a partition key, the database would not effectively know where to store or retrieve your data. The clustering columns are used to define the order of rows within each partition in a table, but they do not change the necessity of having a partition key. While clustering columns can influence how data is ordered and organized within a partition, the creation of a partition is essential to ensure that data is accessed quickly and efficiently across the distributed architecture of Cassandra. Therefore, omitting the partition key leads to undefined behavior and poor performance, confirming that having a partition key is not optional, even if clustering columns are included.