Design query generation system

Q: Design query generation system

This question evaluates understanding of ML system design for real-time query suggestion and ranking, encompassing competencies in candidate generation and ranking models, data ingestion and labeling pipelines, online/nearline feature engineering, feedback and retraining loops, latency and scalability constraints, multilingual handling, and safety/policy compliance. It is commonly asked to assess the ability to balance trade-offs between model quality, latency, throughput, and guardrails in operational systems; the domain is ML System Design and the level of abstraction combines practical application with systems-level conceptual reasoning.

Q: How do I approach ML System Design interview questions?

ML System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master ml system design interviews.

Question

System Design: Query-Generation to Maximize CTR

Context

You are designing a real-time system that generates and ranks search query suggestions shown to users (e.g., in a mobile app search box or entry points). The objective is to maximize click-through rate (CTR) on these suggested queries while meeting low-latency and high-scale requirements.

Assume:

Real-time suggestions under 100 ms p95 latency.
Tens to hundreds of millions of daily users, multilingual content.
Safety and policy compliance are required.

Task

Describe an end-to-end design covering:

High-level architecture (online and offline paths).
Data ingestion and labeling pipeline.
Feature engineering (online/nearline readiness).
Models for candidate generation and ranking (training and serving).
Feedback/learning loop (exploration, debiasing, retraining).
Evaluation: key offline and online metrics (with definitions).

Discuss key trade-offs, cold-start handling, safety/guardrails, and latency budgets.

Design query generation system

System Design: Query-Generation to Maximize CTR

Context

Task

Solution

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