auto_increment_increment 和 auto_

官网：https://dev.mysql.com/doc/refman/5.7/en/replication-options-source.html#sysvar_auto_increment_increment

• auto_increment_increment 和 auto_increment_offset ：长度限制 1-65535
• 一般 auto_increment_increment 值更改是由于主主复制或MGR架构所需，正常这俩个值均不会更改。
• auto_increment_increment ： 设置间隔步长
• auto_increment_offset：设置初始值，且影响auto_increment值
• 当 auto_increment_offset > auto_increment_increment 时，auto_increment_offset被默认设置为1
• 当 auto_increment_offset <= auto_increment_increment,自增值计算方式是这样的：值 = auto_increment_offset + N*auto_increment_increment

mysql> set auto_increment_increment = 5;
Query OK, 0 rows affected (0.00 sec)

mysql> set auto_increment_offset=2;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%auto_incre%';
+--------------------------+-------+
| Variable_name            | Value |
+--------------------------+-------+
| auto_increment_increment | 5     |
| auto_increment_offset    | 2     |
+--------------------------+-------+
2 rows in set (0.00 sec)

mysql> create table t(id int auto_increment primary key);
Query OK, 0 rows affected (0.04 sec)

mysql> insert into t values(NULL), (NULL), (NULL), (NULL);
Query OK, 4 rows affected (0.01 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> select * from t;
+----+
| id |
+----+
|  2 |
|  7 |
| 12 |
| 17 |
+----+
4 rows in set (0.00 sec)