What is an "Index Table" in Cassandra?

An "Index Table" in Cassandra is specifically designed to enhance query performance on non-primary key columns. In this distributed database system, primary keys play a crucial role in how data is stored and accessed. However, for queries that require filtering based on non-primary key attributes, an index table becomes essential.

By creating an index on a non-primary key column, Cassandra allows for efficient searching and retrieval of records based on those columns. This is particularly beneficial in scenarios where there are complex queries looking for specific values that are not part of the primary key. Consequently, using index tables can significantly reduce the latency and improve the overall performance of read operations.

In contrast, while other choices mention aspects like faster data writes or data backup, they do not accurately describe the primary function of index tables in Cassandra. The ability to query efficiently based on non-primary keys is what fundamentally distinguishes index tables in this database environment.