Design a pin search engine
Company: Pinterest
Role: Machine Learning Engineer
Category: ML System Design
Difficulty: medium
Interview Round: Onsite
Design a search engine for visual content items such as pins. Explain how you would efficiently generate candidates for a query, what retrieval and ranking models you would use, which loss functions are appropriate, whether pairwise ranking is suitable, what offline metrics you would track, and what features you would include.
Quick Answer: This question evaluates competency in designing large-scale visual search systems, including efficient candidate generation, retrieval and ranking model selection, appropriate loss functions, offline evaluation metrics, and feature engineering for image-based content.