Database / ScyllaDB Interview questions
What are the types of consistency levels in ScyllaDB?
ScyllaDB, like Cassandra, offers tunable consistency, letting each read or write specify how many replicas must acknowledge before the operation succeeds.
| Level | Meaning |
| ONE / TWO / THREE | That exact number of replicas must respond. |
| QUORUM | A majority of all replicas across the cluster. |
| LOCAL_QUORUM | A majority of replicas within the local datacenter only. |
| ALL | Every replica must respond. |
| ANY (write-only) | Succeeds even if only a hinted handoff was stored. |
Choosing a consistency level is a trade-off between latency/availability and strictness: ONE is fastest but can return stale data, while ALL guarantees freshness but fails if even one replica is unreachable. LOCAL_QUORUM is a common default for multi-datacenter clusters since it gives strong consistency within a region without paying cross-datacenter round-trip latency.
Which consistency level requires a majority of replicas within the local datacenter?
Which write-only consistency level can succeed via just a hinted handoff?
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