ashkangoleh

-- first query all the users 
WITH offsets AS (SELECT a.*,
                        EXTRACT(hour FROM ptn.utc_offset) AS utc_offset
                 FROM bootcamp.attendees a
                          JOIN pg_timezone_names ptn ON a.timezone = ptn.name
                 WHERE a.bootcamp_version = 3
                   AND a.timezone IS NOT NULL
                   AND a.content_delivery = 'Live'::text
                  ),
-- then aggregate the users by track and offset, we want matching timezones to fill up first