System Design Interview Fundamentals Rylan Liu Pdf May 2026

System Design Interview Fundamentals — Detailed Guide

Overview

This guide summarizes core topics usually covered in system design interview prep (inspired by common resources like Rylan Liu’s materials). It outlines frameworks, common components, design patterns, trade-offs, and practice problems with step-by-step approaches you can apply in interviews.

Part 4: Why the "PDF" Format is Perfect for Interview Prep

You might ask: "Why a PDF? Why not a video course?" System Design Interview Fundamentals Rylan Liu Pdf

• Functional Requirements: What exactly are we building? (Upload image? Post tweet? Book seat?)
• Non-Functional Requirements (The "ilities"):

  7. Common System Design Questions (How to Apply)

  • Design URL shortener – Focus on 6‑7 character keys, base‑62 encoding, async write‑back to analytics DB.
  • Design chat system – WebSocket for real‑time, message queue for offline users, NoSQL for history.
  • Design social media feed – Pull (fan‑out on read) vs. push (fan‑out on write) models. Often hybrid.
  • Design video streaming platform – CDN + blob storage + adaptive bitrate streaming.

  Scale Estimation: Calculating QPS, storage, and bandwidth needs. Functional Requirements: What exactly are we building

  • Token bucket implemented in Redis with Lua scripts for atomicity, distributed across regions; per-user and per-IP keys with TTL.

  Example: Storage sizing

  • Use SQL (Postgres/MySQL) when: