System Thinking Applied

Now that you understand the framing, let's apply it. The key is to make your thinking visible: state constraints, estimate numbers, and name alternatives before committing.

Constraint-First in Action

When given "Design a URL shortener," don't jump to hashing. First:

• Scale: 100M redirects/day? 10B? Affects storage and cache strategy.
• Latency: p99 < 100ms? Impacts DB choice.
• Character set: Alphanumeric only? Affects short code length.

Inline Check 1

For a news feed with 50M DAU, what order-of-magnitude reads per second should you plan for?

<!-- quiz-candidate: true -->

Inline Check 2

Name one trade-off between consistency and availability in a distributed system.