ML SystemPart 5: Case StudiesChapter 5
Case Studies CH.05 ~20 min
Case Studies
Interview methodology, Twitter Timeline, and Instagram Storage.
interviewback-of-the-envelopeTwitter architectureInstagram architecture
- Execute system design steps methodically.
- Perform rough storage and bandwidth capacity estimations.
- Analyze Twitter and Instagram architectures.
- Evaluate trade-offs in implementing fan-out features.
01 Design Methodology: Thinking Like an Architect Viz
- **Clarification**: Ask about system constraints (DAU, Read/Write ratio).
- **Estimation**: Roughly calculate storage and bandwidth needs (Back-of-the-envelope).
- **High-level Design**: Sketch the main flow (User -> Load Balancer -> App -> DB).
- **Component Detail**: Discuss sharding, caching, and queues in depth.
- **Trade-off Discussion**: Explain why you chose that particular solution.
Rough Calculations
Use 'Powers of Two' for quick estimations. For example: 2^20 is ~1 million, 2^30 is ~1 billion.
Back-of-the-envelope calculation
A rough estimate performed quickly to validate a design idea.
02 Case Study 1: Designing Twitter (Timeline)
Twitter uses aggressive caching for timelines.Deeper InsightYour timeline is actually pre-computed before you even open it. Click to collapse
| Feature | Challenge | Solution |
|---|---|---|
| Posting Tweet | High traffic | Queueing & Async Write |
| Reading Timeline | Low latency | Redis Pre-computed Timeline |
| Search | Keyword indexing | Elasticsearch / Lucene |
Simplified architecture of Twitter's main features.
03 Case Study 2: Designing Instagram (Photos & Feed)
- **Object Storage**: For raw image/video files.
- **Graph Database**: To map 'Follow' and 'Like' relationships.
- **CDN**: Essential for fast photo delivery worldwide.
Final Advice
Learn from failures. Read engineering post-mortems from large companies to understand how systems fail at scale.
Key Takeaways
- 1Always start with requirement clarification before designing.
- 2Capacity estimation helps you choose the right technology from the start.
- 3Every major application (Twitter, Instagram) has unique challenges requiring specific solutions.
- 4Learning from real-world architectures is the best way to master system design.
CH.05
Chapter Complete
Chapter Progress
Reading
Exercise
Interact with the visualization
Quiz
Methodology & Case Studies Quiz
Test your understanding of the system design process and real-world case studies.
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5 questionsRandomized from pool70% to pass