08/11/2025
How Redis works
Getting a bit technical — here’s a simplified breakdown of the internal mechanics of Redis.
• In-memory store – Redis keeps data in RAM, so reads/writes bypass slower disk access.
• Single-threaded core (for commands) – Many operations run in a single thread but are extremely efficient; non-blocking I/O and event loop handle concurrency.
• Persistence options:
RDB (snapshotting): takes snapshots of dataset at intervals.
AOF (Append-Only File): logs each write operation; can be configured for fsync frequency.
• Data Structures: Strings, Lists, Sets, Sorted Sets, Hashes (and with modules even Streams, Graphs, JSON).
• Replication & high availability: primary/replica setups, clustering, sharding.
• Eviction/expiry policies: When memory hits max, Redis can evict keys based on policy (LRU, LFU etc).
🔍 What this means for you as a developer:
• Choose your persistence mode based on durability vs performance trade-off.
• Monitor memory usage and set appropriate maxmemory/eviction settings.
• Leverage the right data structure for your use-case: e.g., Sorted Sets for a leaderboard, Lists for a queue.
Stay tuned: next post I’ll cover common use-cases & best practices with Redis in production.
