CREATE TABLE t1 (
a int NOT NULL PRIMARY KEY,
b varchar(32),
c char(16),
d date,
e double,
f bit(3),
INDEX idx1 (b, e),
INDEX idx2 (c, d),
INDEX idx3 (d),
INDEX idx4 (e, b, d)
) ENGINE= MYISAM;
INSERT INTO t1 VALUES
(0, NULL, NULL, NULL, NULL, NULL),
(7, 'xxxxxxxxxxxxxxxxxxxxxxxxxx', 'dddddddd', '1990-05-15', 0.1, b'100'),
(17, 'vvvvvvvvvvvvv', 'aaaa', '1989-03-12', 0.01, b'101'),
(1, 'vvvvvvvvvvvvv', NULL, '1989-03-12', 0.01, b'100'),
(12, 'wwwwwwwwwwwwwwwwwwwwwwwwwwww', 'dddddddd', '1999-07-23', 0.112, b'001'),
(23, 'vvvvvvvvvvvvv', 'dddddddd', '1999-07-23', 0.1, b'100'),
(8, 'vvvvvvvvvvvvv', 'aaaa', '1999-07-23', 0.1, b'100'),
(22, 'xxxxxxxxxxxxxxxxxxxxxxxxxx', 'aaaa', '1989-03-12', 0.112, b'001'),
(31, 'wwwwwwwwwwwwwwwwwwwwwwwwwwww', 'aaaa', '1999-07-23', 0.01, b'001'),
(10, NULL, 'aaaa', NULL, 0.01, b'010'),
(5, 'wwwwwwwwwwwwwwwwwwwwwwwwwwww', 'dddddddd', '1999-07-23', 0.1, b'100'),
(15, 'vvvvvvvvvvvvv', 'ccccccccc', '1990-05-15', 0.1, b'010'),
(30, NULL, 'bbbbbb', NULL, NULL, b'100'),
(38, 'zzzzzzzzzzzzzzzzzz', 'bbbbbb', NULL, NULL, NULL),
(18, 'zzzzzzzzzzzzzzzzzz', 'ccccccccc', '1990-05-15', 0.01, b'010'),
(9, 'yyy', 'bbbbbb', '1998-08-28', 0.01, NULL),
(29, 'vvvvvvvvvvvvv', 'dddddddd', '1999-07-23', 0.012, b'010'),
(3, 'yyy', 'dddddddd', '1990-05-15', 0.112, b'010'),
(39, 'zzzzzzzzzzzzzzzzzz', 'bbbbbb', NULL, 0.01, b'100'),
(14, 'xxxxxxxxxxxxxxxxxxxxxxxxxx', 'ccccccccc', '1990-05-15', 0.1, b'100'),
(40, 'zzzzzzzzzzzzzzzzzz', 'bbbbbb', '1989-03-12', NULL, NULL),
(44, NULL, 'aaaa', '1989-03-12', NULL, b'010'),
(19, 'vvvvvvvvvvvvv', 'ccccccccc', '1990-05-15', 0.012, b'011'),
(21, 'zzzzzzzzzzzzzzzzzz', 'dddddddd', '1989-03-12', 0.112, b'100'),
(45, NULL, NULL, '1989-03-12', NULL, b'011'),
(2, 'wwwwwwwwwwwwwwwwwwwwwwwwwwww', 'ccccccccc', '1990-05-15', 0.1, b'001'),
(35, 'yyy', 'aaaa', '1990-05-15', 0.05, b'011'),
(4, 'vvvvvvvvvvvvv', 'dddddddd', '1999-07-23', 0.01, b'101'),
(47, NULL, 'aaaa', '1990-05-15', 0.05, b'010'),
(42, NULL, 'ccccccccc', '1989-03-12', 0.01, b'010'),
(32, NULL, 'bbbbbb', '1990-05-15', 0.01, b'011'),
(49, 'wwwwwwwwwwwwwwwwwwwwwwwwwwww' , 'aaaa', '1990-05-15', NULL, NULL),
(43, 'wwwwwwwwwwwwwwwwwwwwwwwwwwww' , 'bbbbbb', '1990-05-15', NULL, b'100'),
(37, 'yyy', NULL, '1989-03-12', 0.05, b'011'),
(41, 'xxxxxxxxxxxxxxxxxxxxxxxxxx', 'ccccccccc', '1990-05-15', 0.05, NULL),
(34, 'yyy', NULL, NULL, NULL, NULL),
(33, 'zzzzzzzzzzzzzzzzzz', 'dddddddd', '1989-03-12', 0.05, b'011'),
(24, 'wwwwwwwwwwwwwwwwwwwwwwwwwwww', 'dddddddd', '1990-05-15', 0.01, b'101'),
(11, 'yyy', 'ccccccccc', '1999-07-23', 0.1, NULL),
(25, 'zzzzzzzzzzzzzzzzzz', 'bbb', '1989-03-12', 0.01, b'101');
ANALYZE TABLE t1;
SELECT COUNT(DISTINCT t1.e, t1.b, t1.d) FROM t1;
DROP TABLE t1;
The problem can be easily reproduced with the following simple test case: