System DesignAdvanced
How to Design a Recommendation System That Actually Works
Building a scalable recommendation system requires moving beyond basic collaborative filtering to a robust funnel architecture capable of handling 100 million users. A production-grade design separates online serving from offline training, utilizing distinct stages for candidate generation, scoring, and ranking to meet strict latency requirements under 200 milliseconds. Key components include vector databases for efficient similarity search and two-tower neural networks that learn complex user-item interactions. The architecture must address cold start problems for new users and handle high-throughput event logging using distributed systems like Kafka. Engineers must balance the mathematical rigor of matrix factorization with infrastructure constraints, optimizing for metrics like Queries Per Second (QPS) and P99 latency. The architecture provides a practical framework for evaluating retrieval, ranking, latency, cold-start, and infrastructure trade-offs in a large recommendation system.
