System Design Complete Course

Overview

• Introduction to system design concepts and importance.
• Topics covered include:
  • Relational data modeling
  • Horizontal vs. vertical scaling
  • Stateless vs. stateful systems
  • Load balancing
  • Caching
  • System design interview questions & mock interviews

Lecture Breakdown

1. Relational Data Modeling

• Understanding user profiles and their attributes:
  • User Entity Table
    • Attributes: ID, Profile Pic, Name, Contact Info, Skills
• Skills can be modeled using a mapping table due to many-to-many relationships:
  • User Skills Table
    • Attributes: ID, User ID, Skill ID

2. Educational Institutions and Employers

• Create an Organization entity for both educational and employment data.
• Split into two tables: Education and Employer with attributes like ID, Name, Start Year, End Year.
• Create mapping tables for user education and user employment.

3. Recommendations

• Create a Recommendation entity with:
  • Attributes: ID, Recommendation Giver (User ID), Recipient ID

4. Connections and Followers

• Design a Connections table with:
  • Attributes: ID, User ID 1, User ID 2, Acceptance Flag
• This helps manage followers and connections efficiently.

5. Posts, Comments, and Likes

• Post Entity:
  • Attributes: ID, User ID, Text
• Comment Entity:
  • Attributes: ID, User ID, Post ID, Text
• Combine like tables for posts and comments into one to optimize space.

6. Load Balancing

• Importance of load balancing in high-scale environments.
• Load balancers can be hardware or software solutions (Layer 4 vs Layer 7).

7. Stateless vs Stateful Systems

• Stateless systems: Do not store user state, easier to scale.
• Stateful systems: Require context storage, harder to scale but may be necessary in certain applications.

8. Consistent Hashing

• Efficient way to distribute load across servers without requiring reallocation of all keys when servers are added or removed.

9. Caching

• Caching reduces latency by storing frequently accessed data closer to the user.
• Discussed write-through and write-back caching strategies.

Example Case Study: Delicious

• Overview of scaling challenges faced by the Delicious bookmarking site.
• Transition from vertical scaling to horizontal scaling.
• Importance of DNS and load balancing in handling traffic.

Key Takeaways

• Design principles are crucial for scalability, efficiency, and user experience.
• Understand the requirements before diving into system design.
• Emphasize extensibility and maintainability when designing systems.

Conclusion

• Importance of continuous learning in system design.
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