🟥 Redis

Core → Advanced

• Data structures: strings, hashes, lists, sets, sorted sets (leaderboards, rate limits), bitmaps, HyperLogLog, geo, streams
• Single-threaded event loop (+ I/O threads); why it’s fast; big-key and hot-key problems
• TTLs and eviction policies (LRU/LFU variants)
• Caching patterns: cache-aside, read-through, write-through, write-behind; invalidation strategies
• Cache stampede prevention: locking/singleflight, probabilistic early expiry, jittered TTLs
• Transactions (MULTI/EXEC), Lua scripts / Functions for atomic ops
• Distributed locks: SET NX PX + fencing tokens; Redlock controversy
• Rate limiting: fixed window, sliding log, sliding window counter, token bucket (Lua)
• Pub/Sub vs Streams (consumer groups)
• Persistence: RDB vs AOF; replication; Sentinel vs Cluster (hash slots)
• Pipelining; client-side caching
• Vector search in Redis (awareness); semantic caching for LLMs
• Licensing landscape: Redis vs Valkey fork (know that Valkey exists and is used by AWS/Google)

🧪 Labs (🟢 warm-up → 🟡 core → 🔴 hard → ⚫ boss)

• 🟢 OBJECT ENCODING/MEMORY USAGE experiments
• 🟡 Token-bucket quotas in Lua with hash tags per tenant (cluster-safe)
• 🔴 A semantic cache index (vector search) vs an exact cache for the gateway
• ⚫ Build your own Redis (Go): replication or RDB stage

🧠 Cognitive tasks

• Predict the pipelining speedup; explain it with RTT math

🛰️ Orbit integration

• Gateway quotas + cache, orbit-stream pub/sub + resume buffers, API-key revocation

Go deeper

⚙️ Redis Internals

Resources

• redis.io docs + Redis University (free) · Redis in Action (dated but conceptually good)