Cassandra Practice Test 2025 – Comprehensive All-in-One Guide to Exam Success!

In the context of SSTables, the term 'immutable' refers to the property that data cannot be changed once it has been written to the storage. This means that when data is stored in an SSTable, it is fixed and cannot be modified or deleted in place. If a change is necessary, a new entry is created with the updated data, and the old entry can be invalidated during the compaction process.

This design choice contributes to the overall efficiency, reliability, and performance of the Cassandra database. Immutable data structures help in achieving high write throughput because they eliminate the need for locking mechanisms that are generally required in mutable structures. Additionally, immutability simplifies the management of data snapshots, backup, and recovery operations, since the data remains unchanged once written.

The other options address different concepts not relevant to the definition of immutability in SSTables. Data being randomly accessed pertains to how data is retrieved, storage being temporary refers to volatile memory, and encryption is a security measure rather than a characteristic of data immutability.