lateral_join_funnel_1.sql

SELECT 
  user_id,
  view_homepage,
  view_homepage_time,
  enter_credit_card,
  enter_credit_card_time
FROM (
  -- Get the first time each user viewed the homepage.
  SELECT
    user_id,
    1 AS view_homepage,
    min(time) AS view_homepage_time
  FROM event
  WHERE
    data->>'type' = 'view_homepage'
  GROUP BY user_id
) e1 LEFT JOIN LATERAL (
  -- For each row, get the first time the user_id did the enter_credit_card
  -- event, if one exists within two weeks of view_homepage_time.
  SELECT
    1 AS enter_credit_card,
    time AS enter_credit_card_time
  FROM event
  WHERE
    user_id = e1.user_id AND
    data->>'type' = 'enter_credit_card' AND
    time BETWEEN view_homepage_time AND (view_homepage_time + 1000*60*60*24*14)
  ORDER BY time
  LIMIT 1
) e2 ON true