Design Interview Pdf: Alex Lu System

Requirement: 100M URLs/month, 1000 writes/sec, 10k reads/sec Choice A: Base62 encoded ID (DB auto-increment) → Simple but predictable IDs Choice B: Snowflake ID (timestamp + worker ID) → Unpredictable, 64-bit, no DB roundtrip Winner for scale: Snowflake, but add cache for hot keys. Consistency: Not critical (shortened link not changing). Use eventual consistency.

Foundational concepts (Load balancers, Caching, Databases) and common interview questions like URL Shorteners and News Feeds. Alex Lu System Design Interview Pdf