Grab — Driver Supply Gap

Grab's regional ops team wants to know which city is most under-supplied with drivers, hour by hour, on 12 Jan 2026. You have two tables — ride requests and driver shifts — and no pre-joined view. Five sequential steps: count demand, count supply, combine them into a stretch ratio, find each city's worst hour with a window function, then name the single city to staff first.

Schema

▸grab_ride_requests

request_id	SERIAL
city_id	TEXT
requested_at	TIMESTAMP

▸grab_driver_shifts

shift_id	SERIAL
driver_id	INT
city_id	TEXT
shift_start	TIMESTAMP
shift_end	TIMESTAMP

5 steps

1Count ride requests per city per hour
2Count online drivers per city per hour
3Compute the demand-to-supply ratio per city-hour
4Find each city's peak-stretch hour with a window function
5Name the one city ops should staff first

Basic

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