Practical System Design
Design at scale - and defend your trade-offs.
The capstone: designing systems that scale, and reasoning about the trade-offs out loud - the skill tested in every senior interview and every real design review. A repeatable approach to any design problem, back-of-envelope capacity estimation, caching, databases at scale, queues for decoupling and load-leveling, and a full worked design that ties it all together.
Lessons in this stage
- 01
A Repeatable Approach
IntermediateA framework for any design problem or interview: clarify functional and non-functional requirements, estimate scale, sketch a high-level design, deep-dive the hard parts, then find the bottlenecks.
14 min - 02
Capacity Estimation
AdvancedBack-of-the-envelope math: requests per second, storage and bandwidth, read/write ratios, and the latency numbers every engineer should carry in their head.
15 min - 03
Caching
AdvancedThe first tool you reach for at scale: cache-aside vs. write-through vs. write-behind, eviction and TTLs, the hard problem of invalidation, and where a CDN fits.
16 min - 04
Databases at Scale
AdvancedWhen one database isn't enough: read replicas, sharding and partitioning, SQL vs. NoSQL, and the CAP theorem's forced choice between consistency and availability under a partition.
16 min - 05
Queues & Load-Leveling
AdvancedMessage queues as the shock absorber of a system: decoupling producers from consumers, leveling spiky load, back-pressure, and at-least-once delivery with idempotent consumers.
14 min - 06
A Worked Design
AdvancedEverything together on one problem - designing a scalable URL shortener - from requirements and estimation through the data model, caching, sharding, and the trade-offs you'd defend.
16 min