The Shape of a Run
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
- L5
Interview Prompt
Every machine in our fleet emits one log line when a process starts and a separate line when it stops, and each line records the machine, a process id the machine assigns locally, which kind of event it was, and a timestamp in float seconds. The warehouse has to keep every line exactly as it arrived so analysts can reconcile a start with its matching stop themselves, computing the average elapsed time per process, drawing per-machine timelines of every process in order, and flagging starts that never got a stop. Design the data model behind this log and describe how the daily files load in through an ETL.
Summary
Two log lines bracket every process. Pair them and the fleet's rhythm appears.
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