COMPACT 行记录格式

CREATE TABLE `mytest` (
`t1` varchar(10) DEFAULT NULL,
`t2` varchar(10) DEFAULT NULL,
`t3` char(10) DEFAULT NULL,
`t4` varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT

mysql> select * from mytest;
+------+------+------+------+
| t1 | t2 | t3 | t4 |
+------+------+------+------+
| a | bb | bb | ccc |
| d | ee | ee | fff |
| d | NULL | NULL | fff |
+------+------+------+------+

mysql> select hex(t1),hex(t2),hex(t3),hex(t4) from mytest; 
+---------+---------+---------+---------+
| hex(t1) | hex(t2) | hex(t3) | hex(t4) |
+---------+---------+---------+---------+
| 61      | 6262    | 6262    | 636363  |
| 64      | 6565    | 6565    | 666666  |
| 64      | NULL    | NULL    | 666666  |
+---------+---------+---------+---------+

hexdump -C mytest.ibd