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What is Valkey, and why did the community fork it from Redis?
Databases & Caching · Intermediate level
Answer
Valkey is an open-source Redis-compatible datastore forked after Redis changed its license. It preserves a community-governed open-source path while aiming to keep Redis protocol and command compatibility.
Technical explanation
Wire compatibility does not guarantee every feature, module, metric, or managed-service setting behaves identically.
If the workload is pure cache, cutover can tolerate misses; if Redis holds authoritative data, migration must be much stricter.
Validation should compare hit ratio, latency, evictions, memory, CPU, connection count, app errors, and failover behavior.
Hands-on example
Migration runbook:
1. Inventory Redis version, commands, clients, Lua scripts, modules, ACLs, cluster mode, and parameters.
2. Create equivalent Valkey cluster.
3. Restore backup or use online migration if supported.
4. Test staging app and replay synthetic traffic.
5. Lower TTLs and warm hot keys.
6. Switch endpoint/secret.
7. Monitor p95 latency, hit ratio, evictions, CPU, memory, and errors.
8. Keep old cluster for rollback window.
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