Design a typeahead search service
Company: Microsoft
Role: Software Engineer
Category: System Design
Difficulty: hard
Interview Round: Technical Screen
Design a search autocomplete system for a large application. As a user types a prefix, the system should return relevant suggestions with low latency.
Clarify and address the following:
- What are the functional requirements for prefix matching, ranking, personalization, and result freshness?
- What APIs would you expose for querying suggestions and updating the underlying corpus?
- How would you model and store the suggestion data?
- How would you support fast prefix lookup at scale?
- How would you rank results using factors such as popularity, language, recency, and user-specific behavior?
- How would the system handle frequent updates, cache invalidation, and high query volume?
- What trade-offs would you make between latency, memory usage, and freshness?
Overview: This question evaluates competency in large-scale system design, including scalable data modeling, low-latency prefix lookup, ranking and personalization strategies, API design, caching, and trade-off analysis.