SQL VERTICA group by intervals

How to group records by interval 4 hours?

For example, I have rows that contain data about events durations.

I want to group them but max duration of 1 row should be 4 hours.

Result:

I tried to use something like this to display an increased duration but no idea how to use it for grouping

select sum(end_date - start_date) over (partition by event_id order by start_date)

• MIN(start_date) OVER (PARTITION BY event_id) to find the earliest start_date for each event_id.
• Use FLOOR to assign a group number based on the 4 hour interval.
• MIN(start_date) and MAX(end_date) to find the start and end times for each group.

WITH grouping AS (
    SELECT 
        event_id, 
        start_date, 
        end_date,
        MIN(start_date) OVER (PARTITION BY event_id) AS first_start_date,
        FLOOR(
            TIMESTAMPDIFF('second', MIN(start_date) OVER (PARTITION BY event_id), start_date) 
            / (4 * 3600)
        ) AS group_num
    FROM event
)
SELECT
    event_id,
    MIN(start_date) AS start_date,
    MAX(end_date) AS end_date
FROM grouping
GROUP BY event_id, group_num
ORDER BY event_id, start_date;