This came up on the Hive mailing list and I’m putting it here as a reminder to try it out. Here’s how to do complex count statements to simplify queries.
SELECT
type
, count(*)
, count(DISTINCT u)
, count(CASE WHEN plat=1 THEN u ELSE NULL END)
, count(DISTINCT CASE WHEN plat=1 THEN u ELSE NULL END)
, count(CASE WHEN (type=2 OR type=6) THEN u ELSE NULL END)
, count(DISTINCT CASE WHEN (type=2 OR type=6) THEN u ELSE NULL END)
FROM
t
WHERE
dt in ("2012-1-12-02", "2012-1-12-03")
GROUP BY
type
ORDER BY
type
;