This module covers how Node.js applications persist, cache, and communicate with data stores and message brokers. From CRUD operations with SQL and NoSQL databases to high-performance caching with Redis and asynchronous processing with message queues — you’ll learn the patterns used by every production Node.js backend.

Data is the heart of most applications. Choosing the right database, caching strategy, and async processing pattern directly impacts your application’s performance, scalability, and reliability. This module teaches you how to design the data layer for production workloads.

flowchart LR
    DB["4.1 Working with Databases"] --> Cache["4.2 Caching with Redis"]
    DB --> Queue["4.3 Message Queues"]
    Cache --> Prod["Production Deployments"]
    Queue --> Prod

    style DB fill:#4f46e5,color:#fff
    style Cache fill:#dc2626,color:#fff
    style Queue fill:#059669,color:#fff
    style Prod fill:#7c3aed,color:#fff

Common questions: SQL vs NoSQL, connection pooling, N+1 queries, cache invalidation, CAP theorem, message queue patterns, eventual consistency.