Exercise: Sessionization and Time-Based Grouping
Last Updated: May 12, 2026
1 min read
For this exercise, we will work with below data:
SQL
Exercise 1
Medium
Write a query that returns each stream event with the gap (in minutes) since the previous stream by the same user. Use LAG over started_at partitioned by user_id. Show user_id, stream_id, started_at, and gap_minutes (NULL for each user's first event). Limit to user 1 only. Order by started_at.
SQL