The Heat of the Map
A hard 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
- 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
- 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