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Three Hours for Yesterday's Numbers

A medium Spark mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.

Domain
Spark
Difficulty
medium
Seniority
senior

Interview Prompt

The nightly `daily_store_sales` Spark job is breaching SLA. It reads a source table of store-level daily sales (one row per store per product per day) and pivots it into one row per store per day with product-level metrics as columns. The job takes 3 hours against a 45-minute SLA because it reads the entire source table every night. Diagnose and fix it.

How This Interview Works

  1. Read the vague prompt (just like a real interview)
  2. Ask clarifying questions to the AI interviewer
  3. Write your spark solution with real code execution
  4. Get instant feedback and a hire/no-hire decision