How do you design a tiny URL or URL shortener?
Direct Answer
This question asks candidates to architect a system that converts long URLs into short, unique aliases. It tests knowledge of distributed systems, hashing algorithms, and database scaling strategies.
Why Interviewers Ask This
Interviewers ask this to evaluate a candidate's ability to handle high-scale web services. They want to see if you can balance trade-offs between storage efficiency, read/write latency, and collision resolution. The question reveals how well you understand consistent hashing, key generation, and the constraints of global redirect systems.
How to Answer This Question
Start by clarifying requirements like traffic volume and retention policies. Propose a hash-based approach for generating short codes, discussing collision handling strategies like double hashing or database lookup. Mention caching layers like Redis to reduce database load and discuss sharding strategies for horizontal scaling. Conclude with considerations for analytics and link expiration.
Key Points to Cover
- URL normalization and hash generation
- Collision resolution strategies
- Caching and database sharding
- Analytics and expiration handling
Sample Answer
To design a URL shortener, I would first normalize the input URL and generate a unique hash using Base62 encoding of a database ID or a MurmurHash of the original string. For scalability, I'd use a distributed ID generat…
Common Mistakes to Avoid
- Ignoring collision scenarios
- Overlooking caching mechanisms
- Failing to define API contracts
- Not considering global scale
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