How do you design a tiny URL or URL shortener system?
Direct Answer
This question assesses your ability to design scalable distributed systems. It tests knowledge of database indexing, hashing algorithms, and load balancing strategies.
Why Interviewers Ask This
Interviewers ask this to evaluate your understanding of large-scale system architecture. They want to see if you can handle high traffic, ensure low latency for redirects, and manage unique ID generation efficiently. The question reveals your ability to trade off consistency, availability, and partition tolerance while designing a robust solution that handles billions of requests daily.
How to Answer This Question
Start by clarifying requirements like read/write ratios and storage limits. Propose a high-level architecture involving a load balancer, API gateway, and multiple database nodes. Discuss hash functions like Base62 for encoding IDs and caching strategies using Redis to reduce database load. Address collision handling and database sharding for scalability. Finally, mention monitoring and error handling mechanisms.
Key Points to Cover
- Scalable database sharding strategy
- Efficient hash function selection
- Multi-tier caching implementation
- Collision avoidance mechanisms
Sample Answer
I would start by defining the scope: we need a service that converts long URLs into short aliases with high availability. I propose using a consistent hashing algorithm to map IDs to specific database shards. For the sho…
Common Mistakes to Avoid
- Ignoring cache invalidation strategies
- Failing to discuss rate limiting
- Overlooking database write bottlenecks
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