Cassandra Practice Test

What is a characteristic of SSTables in Cassandra?

1. SSTables can be modified at any time

2. SSTables are immutable once written

3. SSTables can only store one datatype

4. SSTables automatically delete old data without configuration

The correct answer is: SSTables are immutable once written

SSTables, or Sorted String Tables, are a fundamental component of Cassandra’s storage architecture. One key characteristic of SSTables is that they are immutable once they have been written to disk. This immutability means that after data is written to an SSTable, it cannot be changed; any updates to the data result in new SSTables being created. This design choice enhances performance and simplifies data management because it eliminates concerns related to concurrent writes and allows for easier implementation of compaction and read optimization processes. The immutable nature of SSTables also supports Cassandra's eventual consistency model, as it can efficiently manage how data is stored and retrieved, enabling operations such as merging and cleaning up old data without locking mechanisms. This characteristic is vital for maintaining high write and read throughput in distributed systems like Cassandra.