Jira: Get latest activity for all users after a given date

This query lists active users after a given date. Useful for filtering out inactive users.
In this example, list users who were active in this year (2013):

WITH w_all_user_activities AS
  (SELECT 
    author,
    g.created
  FROM jiraissue i
  INNER JOIN changegroup g ON i.id = g.issueid
  INNER JOIN changeitem c ON c.groupid = g.id
  UNION
  SELECT author, created FROM jiraaction
  UNION
  SELECT reporter, created FROM jiraissue
),
w_tmp_latest_user_activities AS
  (SELECT
    author,
    created,
    RANK() OVER (PARTITION BY author ORDER BY created DESC) dest_rank
  FROM w_all_user_activities
),
w_latest_user_activities AS
  (SELECT 
    author,
    created
  FROM w_tmp_latest_user_activities
  WHERE dest_rank = 1
)
SELECT * FROM w_latest_user_activities 
WHERE created >= TO_DATE('2013-01-01', 'yyyy-mm-dd');