SQL Top 10% by Session Length | Dataford Interview Questions

The Roblox Creator Analytics team wants to identify users with exceptionally high platform engagement. Write a PostgreSQL query that ranks registered Roblox users by their total recorded session length and returns the top 10%.

Requirements

Aggregate all recorded session minutes for each registered user.
Include registered users with no sessions as zero total minutes.
Use a window function to divide users into ten ordered groups, then return the highest group.
Return user_id, username, and total_session_minutes, ordered from highest to lowest total.

Schema

users

Column	Type	Description
user_idPK	INT	Unique Roblox user identifier
username	VARCHAR(50)	Roblox username
platform	VARCHAR(20)	Primary client platform used by the user

user_sessions

Column	Type	Description
session_idPK	INT	Unique session identifier
user_id	INT	Associated Roblox user identifier
session_length_minutes	INT	Session duration in minutes

Your question is SQL Top 10% by Session Length. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem