Quick Answer
Redis is a fast in-memory database used to speed up apps by storing frequently accessed data. It's great for caching, handling sessions, and managing queues, but requires careful memory management since it runs in RAM.
Key Takeaways
- Always set a TTL on cache keys unless you're actively managing expiration
- Monitor memory usage regularly with INFO command
- Use descriptive key names like 'user:123:profile' for clarity
- Speeding up website logins by caching user sessions
- Reducing database load during Black Friday sales
Troubleshooting & Solutions
Common Problems & Solutions
Why this happens
Redis stores everything in memory, so if you don’t limit its size or set eviction policies, it will fill up and crash when full.
How to fix it
- 1Check current memory usage with INFO memory
- 2Set maxmemory directive in redis.conf
- 3Configure an eviction policy like allkeys-lru
Mistakes to avoid
- Running Redis without maxmemory limits
- Using volatile keys for critical data
When to seek help: If memory keeps growing despite eviction rules, consult a DevOps engineer to analyze key access patterns.
Frequently Asked Questions
Yes, but optionally. You can configure RDB snapshots or AOF logging to save data to disk, but it's often used as ephemeral cache where speed outweighs durability.
Sources & References
- [1]Redis — Wikipedia
Wikipedia, 2026