Wrap Up

In this chapter, we designed a news feed system. Our design contains two flows: feed publishing and news feed retrieval.

Like any system design interview questions, there is no perfect way to design a system. Every company has its unique constraints, and you must design a system to fit those constraints. Understanding the tradeoffs of your design and technology choices are important. If there are a few minutes left, you can talk about scalability issues. To avoid duplicated discussion, only high-level talking points are listed below.

Scaling the database:

• Vertical scaling vs Horizontal scaling

• SQL vs NoSQL

• Master-slave replication

• Read replicas

• Consistency models

• Database sharding

Other talking points:

• Keep web tier stateless

• Cache data as much as you can

• Support multiple data centers

• Loosely coupled components with message queues

• Monitor key metrics. For instance, QPS during peak hours and latency while users refreshing their news feed are interesting to monitor.

Congratulations on getting this far! Now give yourself a pat on the back. Good job!

Reference materials#