Scaling Backend Systems

Introduction

Scaling isn't more servers — it's removing the bottleneck. The order is almost always: fix the DB, then add caching, then horizontally scale stateless services.

Understanding the topic

The scaling playbook:

• 🐢 Vertical first — bigger box / faster DB. Cheapest win.
• 🔄 Horizontal — N stateless replicas behind a load balancer.
• 🧊 Cache — Redis between API and DB.
• 📚 Read replicas — offload analytics & dashboards.
• ✂️ Sharding — partition data when one DB can't keep up.
• 📨 Async — push slow work to queues; respond to user fast.
• 🌍 CDN — cache static + cacheable API responses at the edge.