Counted Twice
A medium 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
- medium
Interview Prompt
A daily Python job reads 250,000 orders from Postgres and appends them into a plain Snowflake table that feeds the revenue dashboard. Last Tuesday the job crashed partway through and was retried; the retry loaded every order a second time, leaving 430,000 rows and overstating revenue by 41 percent. Move the destination onto a lakehouse table format such as Delta Lake or Iceberg so that re-running a day's load lands the same rows every time, no matter how often the run repeats.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your pipeline design solution with real code execution
- Get instant feedback and a hire/no-hire decision