Sessionize Events (30 Minute Gap)

A new session starts when a user's gap since their previous event exceeds 30 minutes. Return user_id and the number of sessions per user, ordered by user_id.

Table schema

Events(user_id INT, event_time TIMESTAMP)

Sample data

user_id | event_time
1 | 2026-05-01 10:00:00
1 | 2026-05-01 10:20:00
1 | 2026-05-01 11:30:00
2 | 2026-05-01 09:00:00