1394
1394
EXPLAIN SELECT 1 FROM t1 WHERE a IN
1395
1395
(SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
1396
1396
id select_type table type possible_keys key key_len ref rows Extra
1399
1399
CREATE TABLE t2 (a INT, b INT, KEY(a));
1400
1400
INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4);
1401
1401
EXPLAIN SELECT a, SUM(b) FROM t2 GROUP BY a LIMIT 2;