Database / Apache Cassandra Intermediate and Advanced interview questions
What is the difference between hinted handoff and read repair?
Both mechanisms help replicas converge, but they trigger under different circumstances and fix different kinds of inconsistency.
| Hinted Handoff | Read Repair |
| Triggered when a replica is unreachable during a write. | Triggered when replicas disagree during a read. |
| Coordinator stores a hint and replays it once the node is back. | Coordinator compares responses and pushes the newest value to stale replicas. |
| Fixes missed writes proactively, without needing a read first. | Only fixes rows that are actually queried. |
They complement each other well: hinted handoff catches most short outages quickly, while read repair mops up any divergence hinted handoff missed (for example, if the hint window expired or the coordinator crashed before replaying it). Neither one is a substitute for scheduled anti-entropy repair, which is the only mechanism that guarantees full convergence across all data, read or not.
Hinted handoff activates in response to what event?
What is a shared limitation of both hinted handoff and read repair?
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