System Design

Scale, cache, shard — and know what each choice costs you.

1. 1What Is System DesignChoosing which constraint you refuse to break.5m
2. 2Vertical vs Horizontal ScalingBuy a bigger machine, or buy more of them.5m
3. 3Load BalancingOne front door, many rooms behind it.5m
4. 4CachingKeep the answer near whoever keeps asking.5m
5. 5Invalidation and EvictionWrong answers age; small caches forget.6m
6. 6Content Delivery NetworksDistance is latency you cannot optimise away.5m
7. 7Database ReplicationOne writer, many readers, a small delay.6m
8. 8Database ShardingSplit the data itself when one box is full.6m
9. 9SQL vs NoSQLFixed columns and joins, or flexible documents.6m
10. 10Consistency and CAPWhen the network splits, you must pick a side.6m
11. 11Message QueuesHand off the work instead of waiting for it.5m
12. 12Rate LimitingCap the flow before it caps your service.5m
13. 13Designing a REST APIAddress the thing; let the method be the verb.6m
14. 14WebSockets and RealtimeKeep the line open instead of redialling.5m
15. 15Observability BasicsMetrics say something broke; traces say where.5m