Design a Feed Generation for Capital One

Last updated: March 30, 2026

Quick Overview

Design a distributed feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Capital One
System Design
Software Engineer
Capital One
March 30, 2026
Software Engineer
Onsite
System Design
Easy

20

5

4,245 solved


Design a distributed feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

This ML system design question from Capital One's Onsite tests your ability to think about ML systems at scale. The interviewer expects discussion of data quality, feature stores, model serving infrastructure, and A/B testing strategy.

What the Interviewer Expects
  • Map the business problem to a concrete ML objective
  • Propose reasonable features and a baseline model
  • Discuss basic model evaluation metrics
  • Outline a simple serving architecture
Key Topics to Cover
Monitoring and model degradation detection
Training pipeline and infrastructure
Model selection and architecture
Model serving and latency optimization
Feature engineering and feature stores
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • How would you run A/B tests on different model versions?
  • What is your model retraining strategy?
  • How would you ensure fairness and reduce bias in the model?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For Feed Generation for Capital One, key functional requirements include:...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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