Contributions to level 1-2 vital articles

SQL

WITH vital AS
(
  SELECT Pa.page_id , Pa.page_title, rev_id, actor_name,
   rev_len, LAG(rev_len) OVER (ORDER BY Pa.page_id, rev_id) AS prev_len, LAG(Pa.page_id) OVER (ORDER BY Pa.page_id, rev_id) AS prev_id
  FROM categorylinks
  JOIN page Pt ON Pt.page_id=cl_from AND Pt.page_namespace=1
  JOIN page Pa ON Pa.page_namespace=0 AND Pa.page_title=Pt.page_title
  JOIN revision R ON rev_page=Pa.page_id
  JOIN actor ON actor_id=rev_actor
  WHERE cl_to = "All_Wikipedia_level-1_vital_articles"
)
SELECT actor_name, SUM(CASE WHEN page_id != prev_id THEN rev_len WHEN rev_len > prev_len THEN rev_len - prev_len ELSE 0 END) AS bytes
FROM vital
GROUP BY actor_name
ORDER BY bytes DESC
SQL

Checking query status...
