Cassandra easy
When reading data, choosing `Consistency Level: ONE` (or `LOCAL_ONE`) provides the lowest latency. What is the technical trade-off of this choice?
- A The database will automatically delete the data after it is read to save space.
- B The query returns data as soon as any *single* replica responds, which may result in 'Stale' (outdated) data if the most recent write hasn't reached that node yet.
- C It requires the cluster to have at least 100 nodes to be valid.
- D The client must provide a valid cryptographic certificate for every single data read.
Answer: B. The query returns data as soon as any *single* replica responds, which may result in 'Stale' (outdated) data if the most recent write hasn't reached that node yet.
This is 'Weak Consistency'. It is ideal for non-critical data (like 'Like' counts or logs). By not waiting for a majority (Quorum), you get sub-millisecond responses, but you sacrifice the guarantee that you are seeing the absolute latest version of reality.
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