Database / ScyllaDB Interview questions
What is the difference between ScyllaDB and Apache Cassandra?
| ScyllaDB | Apache Cassandra |
| Written in C++ on the Seastar framework. | Written in Java, runs on the JVM. |
| Shard-per-core, no GC pauses. | Thread-pool based, subject to GC pauses. |
| Wire-compatible with CQL and Cassandra drivers. | Native CQL implementation. |
| Adopted Raft for strongly consistent schema/topology changes. | Uses gossip-based eventually consistent schema propagation. |
| Includes Alternator (DynamoDB-compatible API). | No built-in DynamoDB compatibility. |
Because ScyllaDB re-implements Cassandra's data model and wire protocol, most existing CQL schemas, queries, and drivers work against either system with little to no change, which is why migrations are typically described as a drop-in replacement rather than a rewrite. The practical difference teams notice is throughput per node and tail latency consistency, particularly under high load or with large heaps, rather than a difference in the CQL data model itself.
Which database uses the Seastar framework?
Why is migrating from Cassandra to ScyllaDB often described as a drop-in replacement?
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