环境：

 主、从库的binlog_format = statement

  隔离级别： RC


主库会话1 主库会话2 主库会话3 从库会话


use test;

create table f1(char(2))

engine=InnoDB;

begin;


insert into t1 select 1;

insert into t1 select 2;

insert into t1 select 3;

insert into t1 select 4;

insert into t1 select 5;



begin;


insert into t1 select 'a';

insert into t1 select 'b';

insert into t1 select 'c';

insert into t1 select 'd';

insert into t1 select 'e';

insert into t1 select 'f';


commit;



select * from t1;

+------+

| f1   |

+------+

| a    |

| b    |

| c    |

| d    |

| e    |

| f    |

+------+

select * from t1;

+------+

| f1   |

+------+

| a    |

| b    |

| c    |

| d    |

| e    |

| f    |

+------+
commit




select * from t1;

+------+

| f1   |

+------+

| 1    |

| 2    |

| 3    |

| 4    |

| 5    |

| a    |

| b    |

| c    |

| d    |

| e    |

| f    |

+------+

select * from t1;

+------+

| f1   |

+------+

| a    |

| b    |

| c    |

| d    |

| e    |

| f    |

| 1    |

| 2    |

| 3    |

| 4    |

| 5    |

+------+

可以看到上图中，最后一行，主从库的数据排列顺序变化了。如果这时候我们在主库再执行一个类似 update t1 set f1='A' limit 4; 这种操作，则从库的数据彻底乱了。


下面是执行update时候 主库提示的warnings告警。

master [localhost] {root} (test) > master [localhost] {root} (test) > show warnings \G

*************************** 1. row ***************************

  Level: Note

   Code: 1592

Message: Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. The statement is unsafe because it uses a LIMIT clause. This is unsafe because the set of rows included cannot be predicted.

1 row in set (0.00 sec)