The Speed Layer
A medium Pipeline Design 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
- Pipeline Design
- Difficulty
- medium
- Seniority
- L5
Interview Prompt
Activity events arrive from web and mobile clients, about 60 million a day from roughly 8 million users, and hourly, daily and weekly active users are currently counted from them at query time, which is too slow. Design a pipeline that pre-computes all three, refreshed every hour, and serves them.
Summary
Dashboards can't wait for raw logs. Something has to happen upstream.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Draw your pipeline on the design canvas: sources, transforms, storage and checks
- Answer the interviewer's follow-up questions, then get a hire or no-hire decision