Push It Down
A medium Spark 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
- Spark
- Difficulty
- medium
- Seniority
- L5
Interview Prompt
`user_events` is stored as one folder per `event_date`, and the growth team's 2026 activity rollup has been reading every year of history because its date bound was computed in a separate lookup the file scan never sees. Rebuild it so the scan skips the folders it doesn't need: one row per country with the number of events since the start of 2026.
Summary
You renamed the column. Catalyst forgot how to prune.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write and run your Spark code against the tables
- Answer the interviewer's follow-up questions, then get a hire or no-hire decision