Cassandra Practice Test

Which statement best describes an SSTable?

1. It is a temporary data structure in RAM

2. It is mutable and can be changed

3. It is a formatted data structure stored in disk

4. It directly handles write operations

The correct answer is: It is a formatted data structure stored in disk

An SSTable, or Sorted String Table, is indeed best described as a formatted data structure stored on disk. In the architecture of Cassandra, SSTables are the fundamental unit of storage that contain a sequence of key-value pairs that are sorted by their keys. This sorted order allows for efficient read operations, as binary search can be utilized to quickly locate data. SSTables are immutable, meaning that once written, they cannot be changed. Instead, new entries or updates are handled by creating new SSTables. This design choice significantly enhances Cassandra's ability to handle write operations quickly and efficiently, as it allows data to be written directly to disk without the need to modify existing files. After a certain point, older SSTables may be consolidated through a compaction process, but the original records remain intact in the SSTables until this occurs. Understanding that SSTables are the result of writes to disk helps clarify their role in the overall data management strategy of Cassandra, as they enable efficient reads while maintaining data consistency amidst high-velocity write operations.