Cassandra hard
How does a 'Token-Aware' client driver reduce latency in a Cassandra cluster with 100 nodes?
- A It automatically compresses every request into a single byte.
- B It maintain a local copy of the cluster's token map (metadata) and calculates the hash of the Partition Key locally, sending the query directly to the 'Home' replica.
- C It predicts which node is the least busy by listening to the fan noise of the server.
- D It uses a centralized Load Balancer (like F5 or Nginx) to handle all traffic.
Answer: B. It maintain a local copy of the cluster's token map (metadata) and calculates the hash of the Partition Key locally, sending the query directly to the 'Home' replica.
Without token awareness, a driver might send a query for 'User 123' to Node A. Node A realizes it doesn't own 'User 123' and forwards it to Node B (The 'Extra Hop'). Token-aware drivers calculate that 'User 123' belongs on Node B and talk to Node B directly, reducing latency and cluster-wide 'Chattiness'.
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