The Redis Roadmap

What Redis really is, why it is fast, how a command travels through it, and how to name keys so the rest of the course has solid ground.

Strings, hashes, lists, sets and sorted sets: the commands, the complexity, how each is stored, and the classic problem each one solves.

How keys die: TTLs, lazy and active expiry, maxmemory and eviction policies, and what Redis memory is actually made of.

What's atomic in Redis and what's merely batched: MULTI/EXEC with WATCH, Lua scripts, Redis Functions, and pipelines, with the problem each one solves.

Bitmaps, HyperLogLog, geospatial indexes, Bloom and friends, JSON with secondary indexes, and vector search: the structures that turn a hard problem into one command.

Fire-and-forget Pub/Sub, durable Streams with consumer groups, how they compare to lists, Kafka and RabbitMQ, and the notification features behind client-side caching.

Cache-aside, read-through, write-through and write-behind; invalidation races; penetration, stampede and avalanche; warming and multi-level caches.

Fixed windows, sliding logs and counters, token and leaky buckets, a production-grade distributed limiter, and counters that survive viral traffic.

Client libraries, connection pools and timeouts, Spring Boot and Spring Cache, serialization, distributed sessions, WebSocket fan-out, and how Redis fits next to PostgreSQL and Kafka.

RDB snapshots, the append-only file, fsync policies, fork and copy-on-write, recovery, backups, and exactly how much data a restart can lose.

Asynchronous replication, partial and full resync, replica lag and stale reads, Sentinel failover, split brain, and how to reason about CAP for a real Redis deployment.

16,384 hash slots, CRC16, hash tags and CROSSSLOT, MOVED vs ASK, resharding without downtime, replica elections, and running clusters in production.

Locks with SET NX PX and safe unlock, the lock-expiry race and fencing tokens, Redlock and its critiques, idempotency keys, deduplication, and delayed-job scheduling.

Hot keys, big keys, command complexity, connection and network costs, the metrics that matter, SLOWLOG and LATENCY, and a debugging tree for when Redis goes from 2 ms to 2 s.

Security with ACLs, TLS and network isolation; failure injection for every Redis role; multi-region designs; managed services and Kubernetes; upgrades, backups and disaster recovery.

The pattern catalogue and the anti-patterns, then staff-level designs: analytics, feeds and timelines, driver location, recommendation caches, API gateways, notifications, schedulers, and a full e-commerce capstone.

The full Redis question bank from beginner to staff, with model answers, plus the 25 hands-on builds, study plans by experience level, and the final readiness checklist.