Build the mental model
Redis is a networked, in-memory data-structure server used for low-latency caching, sessions, rate limits, leaderboards, event streams, and messaging. This course references Redis Open Source 8.10, while most core commands also work on recent Redis 7 and 8 installations. Redis is not presented as a PostgreSQL replacement; each system owns the workload it handles best.
Connect it to a real scenario
PostgreSQL remains the durable source of truth for tutorials, users, enrollments, and progress. Redis handles the catalog cache, sessions, request counters, leaderboards, notifications, and background jobs. Every feature is evaluated for cache correctness, expiry, memory, durability, and failure behavior.
Try the working example
PostgreSQL (source of truth)
↕
Node.js API ── Redis 8.10
├─ catalog cache
├─ sessions & rate limits
├─ leaderboard
└─ streams & notificationsYou can explain the Redis/PostgreSQL responsibility split and the course project.5-minute try-it
For one application, list three durable facts and three temporary or derived values that could live in Redis.
One important caution
Do not place all critical data only in Redis just because it is fast; durability and recovery requirements come first.