DROP TABLE IF EXISTS t1, t2;
CREATE TABLE t1 (id INTEGER, grp TINYINT, id_rev INTEGER);
SELECT COUNT(*) FROM t1;
COUNT(*)
4201000
SELECT COUNT(DISTINCT id) FROM t1 GROUP BY grp;
# Begin cleanup
SET session myisam_sort_buffer_size = @orig_myisam_sort_buffer_size;
DROP TABLE t1;