DataDriven
LearnPracticeInterviewDiscussDailyJobs

The What-If Machine

A hard Pipeline Design mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.

Domain
Pipeline Design
Difficulty
hard
Seniority
L5

Interview Prompt

We run an ads platform and want to build a simulation system that matches ad inventory (slots) against ad campaigns to answer what-if questions about fill rates, reach, and frequency. Users should be able to configure a simulation, submit it, and explore the results later. A single configuration might run up to 1,000 simulations. Design the data pipeline behind this system.

Summary

A million slots. A thousand campaigns. Every combination matters.

How This Interview Works

  1. Read the vague prompt (just like a real interview)
  2. Ask clarifying questions to the AI interviewer
  3. Write your pipeline design solution with real code execution
  4. Get instant feedback and a hire/no-hire decision

Related

  • All Mock Interviews
  • Practice Mode (untimed)
  • System Design Interview Questions
  • Data Engineering Interview Prep Guide
  • Practice Problems
  • Daily Challenge