System Design Interview Fundamentals Rylan Liu Pdf High Quality 【Certified】

Report: System Design Interview Fundamentals

Based on common principles from Rylan Liu, Alex Xu, and industry best practices

Pattern C: The Storage Intensive System (e.g., Google Photos, Dropbox)

• The Problem: You can't store a 4K video in a relational database.
• The Solution:
  • Content Delivery: Use a CDN for hot files, Blob Storage (S3) for cold files.
  • Metadata DB: Keep file paths and user permissions in a SQL/NoSQL DB.
  • Async Processing: Upload to blob -> Fire message queue -> Generate thumbnails -> Update DB.

Worked capacity planning examples (quick templates)

Example: Web read path capacity

• Users: 1M daily active; peak concurrent: 100k; average RPS per user during peak 0.1 => RPS = 10k.
• Server capacity: assume one app server handles 200 RPS => need 50 servers + spare capacity => 60 servers.
• Database: read-heavy with read replica handling 80% reads. If baseline DB handles 2000 RPS, need 5 replicas for reads.

Example: Storage sizing

• Average object size: 2 MB, total objects: 50M => raw size = 100 TB.
• Replication (3x) => 300 TB. Add 30% overhead => 390 TB.

Problem B: Design Twitter / X

• Fundamental used: Fan-out on write vs. Fan-out on read.
• The Mistake: Trying to query the global tweet table for every user (read explosion).
• Liu Solution: Timeline service. When a celebrity tweets (high fan-out), write to all followers' timeline tables (slow for celebrity, fast for followers). For normal users, query on read. Trade-off.

2. Load Balancing (L4 vs. L7)

The PDF famously dedicates a full page to the "Load Balancer Decision Tree." System Design Interview Fundamentals Rylan Liu Pdf

• Layer 4 (Transport): Fast, simple, IP-based routing. Good for TCP traffic.
• Layer 7 (Application): Smart routing (by header, cookie, URL path). Essential for microservices.
• The "Liu" Insight: Do not put a load balancer directly in front of a database unless you are managing read replicas. For write-heavy systems, the LB is useless; you need client-side sharding.

9. Common Interview Questions & Short Approaches

1. Design URL shortener
   • Clarify: custom aliases, expiry, analytics.
   • Components: API, DB (key-value), hashing or base62, collision handling, cache, redirect service, analytics pipeline.
   • Scale: QPS, map short->long lookups with caching and CDN where possible.
2. Design scalable chat system
   • Real-time: WebSockets, presence servers, message queue, durable storage, fan-out strategies (direct vs fan-out-on-write), rate limits, offline message sync.
3. Design Twitter-like feed
   • Push vs pull models, fan-out write vs fan-out read, timeline caching, personalization, ranking, write amplification trade-offs.
4. Design file storage (e.g., Dropbox)
   • Object store (S3), metadata DB, chunking, deduplication, consistency, sync client conflict resolution, CDN for downloads.
5. Design search engine for documents
   • Crawler, indexer, inverted index, shards/replicas, query parsing, ranking signals, freshness vs throughput.

11. Practice Tips

• Time-box: practice finishing high-level design in 10–15 minutes and deep dives in remaining time.
• Speak clearly through trade-offs; explicitly state assumptions and numbers.
• Draw diagrams and label components.
• Practice common patterns (caching, sharding, replication, queues).
• Implement mock designs on a whiteboard or collaborative tool; get feedback.

3. Data & Storage Choices

• SQL – Use when ACID transactions, complex queries, or strong consistency are needed.
• NoSQL – Use for massive scale, flexible schemas, or high velocity writes (e.g., Cassandra, DynamoDB).
• Caching – Put a cache (Redis/Memcached) in front of the database to reduce latency & load.
  Common patterns: Cache‑aside, Write‑through, Write‑behind.
• CDN – Cache static assets (images, videos, CSS) at edge locations.

Part 5: How to Study the PDF (A 2-Week Tactical Plan)

You cannot just read the PDF. You must execute it. Report: System Design Interview Fundamentals Based on common

Week 1: The Fundamentals (Read & Annotate) The Problem: You can't store a 4K video

• Day 1-2: Network & Load Balancing. Draw the OSI model.
• Day 3-4: Caching & Databases. Memorize the CAP theorem (Consistency, Availability, Partition Tolerance).
• Day 5-7: Queues & Sharding. Practice consistent hashing on a whiteboard.

Week 2: The Mock Interview (Simulate)

• Take the "Liu Frameworks" and apply them to 5 problems:
  1. Design Netflix (Video streaming).
  2. Design Uber (Geospatial indexing).
  3. Design Web Crawler (Scheduling & deduplication).
  4. Design Chat System (Presence & ordering).
  5. Design Proximity server (Yelp).
• Rule: No talking about specific technologies (e.g., "AWS EC2") for the first 15 minutes. Talk only about fundamentals (e.g., "Stateless compute cluster").