重启mysql对于auto_increment的影响

重启mysql对于auto_increment的影响：
mysql> alter table inc_innodb AUTO_INCREMENT=100;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0


mysql> alter table inc_myisam AUTO_INCREMENT=100;
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0


mysql> show create table inc_innodb;
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table      | Create Table                                                                                                                                                                        |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| inc_innodb | CREATE TABLE `inc_innodb` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=100 DEFAULT CHARSET=utf8 |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)


mysql> show create table  inc_myisam;
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table      | Create Table                                                                                                                                                                        |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| inc_myisam | CREATE TABLE `inc_myisam` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=100 DEFAULT CHARSET=utf8 |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)




重启数据库后，


mysql> use test;
No connection. Trying to reconnect...
Connection id:    2
Current database: *** NONE ***


Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A


Database changed
mysql> show create table inc_innodb;
+------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table      | Create Table                                                                                                                                                                      |
+------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| inc_innodb | CREATE TABLE `inc_innodb` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 |
+------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)


mysql> show create table  inc_myisam;
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table      | Create Table                                                                                                                                                                        |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| inc_myisam | CREATE TABLE `inc_myisam` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=100 DEFAULT CHARSET=utf8 |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)


mysql> select * from inc_innodb;
+----+--------+
| id | name   |
+----+--------+
|  1 | name1  |
|  2 | name22 |
+----+--------+
2 rows in set (0.00 sec)




再次实验update对于innodb的影响：
mysql> update inc_innodb set id=10 where id=1;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0


mysql>  select * from inc_innodb;
+----+-------+
| id | name  |
+----+-------+
| 10 | name1 |
+----+-------+
1 row in set (0.00 sec)


mysql> show create table inc_innodb;
+------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table      | Create Table                                                                                                                                                                      |
+------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| inc_innodb | CREATE TABLE `inc_innodb` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 |
+------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)




重启库
mysql> use test;
No connection. Trying to reconnect...
Connection id:    2
Current database: *** NONE ***


Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A


Database changed
mysql> show create table inc_innodb;
+------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table      | Create Table                                                                                                                                                                       |
+------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| inc_innodb | CREATE TABLE `inc_innodb` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8 |
+------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)




对于innodb来说，重启库之后，会根据现有最大值来判断重启后的AUTO_INCREMENT是多少
对于myisam来说，AUTO_INCREMENT是不会变的


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