Cap Theorem medium
Why is Cassandra classified as an AP system?
- A It utilizes a centralized Leader-Follower architecture designed for strict transactional consistency.
- B It provides native, built-in support for distributed ACID transactions across all regional data centers.
- C It is a strictly single-threaded engine that prevents concurrent write operations at the hardware level.
- D It uses a Peer-to-Peer (Masterless) architecture where any node in the cluster can independently accept writes.
Answer: D. It uses a Peer-to-Peer (Masterless) architecture where any node in the cluster can independently accept writes.
Cassandra is modeled after Amazon's Dynamo. Because it has no single 'Leader' for the entire cluster, there is no 'Leader Election' phase that stops writes during a failure. Any node can accept a write and later propagate it to others. This 'Masterless' design is the definition of a High Availability (AP) system. However, it requires a robust conflict resolution strategy (like LWW) because multiple nodes might accept different values for the same key.
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