This question evaluates a candidate's ability to design scalable, low-latency app marketplace search systems, covering competencies in query understanding, metadata ingestion and indexing, candidate retrieval and ranking, personalization, multilingual and typo-tolerant handling, cold-start and spam prevention, as well as online experimentation and monitoring. Commonly asked in the ML system design/search engineering domain to probe architectural trade-offs, measurement of product requirements and success metrics, and operationalization, it spans both high-level conceptual reasoning and practical application details.
Design the search system for a mobile app marketplace similar to an app store. Users enter short queries such as 'photo editor', 'budget tracker', or an exact app name, and the system should return highly relevant apps with low latency.
Discuss: