What function does the Commit Log serve in Cassandra?

The Commit Log in Cassandra serves the crucial function of recording all write operations to ensure data durability. When a write operation is executed, it is first logged in the Commit Log before being sent to the database's memory structure. This logging guarantees that even in the event of a system failure or crash, the data can be recovered and no write operations are lost. The Commit Log acts as a persistent record, allowing Cassandra to maintain data integrity and reliability.

In the context of the other options, managing user permissions and access involves the authentication and authorization functions of Cassandra, which are separate from the Commit Log's responsibilities. Indexing data for faster retrieval is primarily handled by Cassandra's indexing mechanisms, such as secondary indexes and partitioning strategies, rather than through the Commit Log. Lastly, while schema storage is part of Cassandra's configuration and metadata management, it is distinct from the function of the Commit Log, which focuses solely on recording write operations.