The Heat of the Map
A hard Data Modeling mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- Data Modeling
- Difficulty
- hard
- Seniority
- senior
Interview Prompt
Grab's dispatch team runs a live map showing, for every geohash cell in a city, a surge multiplier driven by how far open requests outrun available drivers and a congestion score comparing observed speed to the road's free-flow speed, refreshed each minute. The schema backs both the always-on map, which needs only the current value in each cell, and analysts who replay how surge built up across a city over the past week. The cells nest, so a coarse cell's surge has to reconcile against the finer cells inside it and up to the one city each cell sits in, and you cannot get there by averaging one cell's ratio with another's.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your data modeling solution with real code execution
- Get instant feedback and a hire/no-hire decision