System Design Interview Alex Hu Pdf |verified| Page

Here’s a useful, practical review of the resource commonly referred to as the System Design Interview by Alex Xu (often searched for as a PDF).

Step 2 – Propose High‑Level Design (5–10 min)

• Draw a block diagram: client → load balancer → web servers → services → databases.
• Mention core components:
  • API gateway / reverse proxy
  • Application servers
  • Caching layer (Redis, Memcached)
  • Database (SQL vs NoSQL)
  • CDN for static assets
  • Asynchronous processing (message queues)

5. Festivals: When the Country Shuts Down (And Lights Up)

You cannot understand Indian lifestyle without surviving a festival season. Unlike the West where holidays are a few days, India has a festival almost every week. system design interview alex hu pdf

• Diwali (Oct/Nov): The Super Bowl of festivals. Fireworks, oil lamps, and enough sweets to give you a sugar high for a month. Offices close, and the skies look like a war zone (be careful with your ears!).
• Holi (March): The color festival. If you go outside, expect to be drenched in colored water. Don't wear nice clothes.
• The key: During major festivals like Diwali and Durga Puja, get your groceries and errands done early. The delivery apps will be slow, and the streets will be euphoric gridlock.

5. Common Calculation Formulas (Back‑of‑the‑envelope)

• QPS = (daily active users × average actions per user) / (86,400 seconds)
• Storage = (data per object × number of objects) × replication factor
• Bandwidth = QPS × average object size (for read‑heavy APIs)
• Memory needed for cache = (QPS × cache TTL) × average object size

Example for URL shortener with 100M writes/month, 10B reads/month: Here’s a useful, practical review of the resource

• Reads QPS = 10B / 2.6M sec ≈ 4k QPS
• Cache size: assume 20% of URLs are hot (2B unique URLs) × 100 bytes = 200GB