Redis Best Practices

Priority: P0 (CRITICAL)

• Security:
• Access Control: Use Redis 6.0+ ACLs (ACL SETUSER) to restrict commands by user/role.
• Encryption: Always enable TLS for data-in-transit (standard in managed Redis like Azure/AWS).
• Dangerous Commands: Disable or rename FLUSHALL, KEYS, CONFIG, and SHUTDOWN in production.
• Connection Resilience:
• Pooling: Use connection pooling with tuned high/low watermarks to avoid connection churn.
• Timeouts: Set strict read_timeout and connect_retries to handle transient network saturation.

Guidelines

• Key Design:
• Namespacing: Use colons to namespace keys (e.g., app:user:123, rate:limit:ip:1.1.1.1).
• Readability vs Size: Keep keys descriptive but compact; avoid keys > 512 bytes.
• Commands & Performance:
• O(N) Avoidance: Use SCAN instead of KEYS. Use UNLINK instead of DEL for background reclamation of large keys.
• Lua Scripting: Prioritize EVALSHA for atomic logic; ensure scripts pre-loaded to save bandwidth.
• Massive Range: Limit ZRANGE, HGETALL, and LRANGE results with offsets/limits.
• Memory Management:
• Eviction Strategy: Use allkeys-lru for general caches and volatile-lru for mixed persistent/ephemeral data.
• Lazy Freeing: Enable lazyfree-lazy-eviction and lazyfree-lazy-expire (Redis 4.0+) to offload cleanup from main thread.
• Monitoring: Watch Used Memory RSS vs Used Memory Dataset. Large fragmentation suggests need for MEMORY PURGE or scaling.

Anti-Patterns

• No sole truth in Redis: Always persist critical data to durable primary database.
• No large blobs: Split values > 100KB into smaller keys or use Hashes for field access.
• No JSON for objects: Use HSET for object fields to enable O(1) access without full decode.
• No TTL-less keys: Set TTL or eviction policy on all non-permanent keys to prevent unbounded growth.

References

• Best Practices Guide
• Checklist