Who Comes Back
A medium Data Modeling mock interview question on DataDriven, with an AI interviewer who asks follow-up questions and a hire or no-hire decision at the end.
- Domain
- Data Modeling
- Difficulty
- medium
- Seniority
- mid
Interview Prompt
We run a short-video social platform and the growth team wants to track how many new users come back on each day after they sign up, broken down by signup cohort and acquisition channel, along with how heavily those returners engage on each day they show up (sessions, videos watched, watch time). Design the warehouse model that lets analysts compute day-N return rates for any offset they ask for later, plus that per-day engagement, without rescanning the raw event stream. Activity is high-volume, so the model has to keep these queries cheap even as the daily activity table grows into the billions of rows.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Draw your data model on the schema canvas: tables, keys and relationships
- Answer the interviewer's follow-up questions, then get a hire or no-hire decision