背景：
一个简单的主从结构，主的binlog format是Mixed模式，在执行一条简单的导入语句时，通过mysqlbinlog导出发现记录的Binlog全部变成了Row的格式（明明设置的是Mixed），现在就说说在什么情况下Binlog的Mixed模式会转变记录成Row格式。
概念：
binlog format有三种形式：Statement、Mixed、Row，具体的信息可以自行到网上搜查。
分析（本文碰到的案例）：
查看MySQL binlog format
dba@192.168.111.4 : dba_test 02:33:39>show variables like 'binlog_format%'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | binlog_format | MIXED | +---------------+-------+
测试语句：
dba@192.168.111.4 : dba_test 02:24:14>create table tmp_test(id int,name varchar(64),age int,primary key(id)) engine = innodb; Query OK, 0 rows affected (0.05 sec)dba@192.168.111.4 : dba_test 02:24:23>insert into tmp_test values(1,'aaa',11); Query OK, 1 row affected (0.02 sec)dba@192.168.111.4 : dba_test 02:25:17>insert into tmp_test values(2,'bbb',22); Query OK, 1 row affected (0.02 sec)dba@192.168.111.4 : dba_test 02:25:23>insert into tmp_test values(3,'ccc',33); Query OK, 1 row affected (0.01 sec)dba@192.168.111.4 : dba_test 02:25:28>insert into tmp_test values(4,'ddd',44); Query OK, 1 row affected (0.01 sec)dba@192.168.111.4 : dba_test 02:25:34>insert into tmp_test values(5,'eee',55); Query OK, 1 row affected (0.01 sec)dba@192.168.111.4 : dba_test 02:25:42>select * from tmp_test; +----+------+------+ | id | name | age | +----+------+------+ | 1 | aaa | 11 | | 2 | bbb | 22 | | 3 | ccc | 33 | | 4 | ddd | 44 | | 5 | eee | 55 | +----+------+------+ 5 rows in set (0.01 sec)dba@192.168.111.4 : dba_test 02:25:50>create table tmp_test_bak(id int,name varchar(64),age int,primary key(id)) engine = innodb; Query OK, 0 rows affected (0.03 sec)dba@192.168.111.4 : dba_test 02:26:31>insert into tmp_test_bak select * from tmp_test; ###记录成了Row模式 Query OK, 5 rows affected (0.03 sec) Records: 5 Duplicates: 0 Warnings: 0
Binlog 记录图：
问题来了，我想要出来的binlog format是Statement，而不是Row。而一条insert into tb select * from ta的简单语句在Mixed模式下记录了Row模式的binlog。原因是什么？
首先确实在一些特定的情况下，Mixed会被转换成Row模式：
. 当 DML 语句更新一个 NDB 表时； . 当函数中包含 UUID() 时； . 2 个及以上包含 AUTO_INCREMENT 字段的表被更新时； . 执行 INSERT DELAYED 语句时； . 用 UDF 时； . 视图中必须要求运用 row 时，例如建立视图时使用了 UUID() 函数；
上面来自网络，有兴趣的可以自己测试测试。而对于本文中的sql，符合不了上面的条件，但binlog也记录成了Row格式。所以还是很奇怪为什么binlog格式被转换了，日常工作的时候有遇到过执行一条sql，会报一个warning：
Warning: Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT 难道因为这个导致转换的？因为上面的SQL可以重现，没有报warning，所以这个情况排除。根据经验想到了一个参数：innodb_locks_unsafe_for_binlog，看到里面讲到事务隔离级别，那就看看隔离级别的情况：
dba@192.168.111.4 : dba_test 05:46:56>select @@global.tx_isolation; +-----------------------+ | @@global.tx_isolation | +-----------------------+ | READ-COMMITTED | +-----------------------+ 1 row in set (0.01 sec)dba@192.168.111.4 : dba_test 06:36:45>select @@session.tx_isolation; +------------------------+ | @@session.tx_isolation | +------------------------+ | READ-COMMITTED | +------------------------+ 1 row in set (0.01 sec)
看到隔离级别是提交读，即不可重复读。把事务隔离级别设置成默认的 REPEATABLE READ：
dba@192.168.111.4 : dba_test 06:41:02>set session transaction isolation level REPEATABLE READ; Query OK, 0 rows affected (0.14 sec)dba@192.168.111.4 : dba_test 06:41:42>select @@session.tx_isolation; +------------------------+ | @@session.tx_isolation | +------------------------+ | REPEATABLE-READ | +------------------------+ 1 row in set (0.00 sec)
再执行测试里的SQL，发现这时候Mixed的binlog记录了Statement格式，正常了，符合预期了。难道就是这个事务隔离级别的问题引起的？在手册里发现了这句：
Note
In MySQL 5.7, when READ COMMITTED isolation level is used, or the deprecated innodb_locks_unsafe_for_binlog system variable is enabled, there is no InnoDB gap locking except for foreign-key constraint checking and duplicate-key checking. Also, record locks for nonmatching
rows are released after MySQL has evaluated the WHERE condition.If you use READ COMMITTED or enable innodb_locks_unsafe_for_binlog, you must use row-based binary logging. 展开可以看例子：
dba@192.168.111.4 : dba_test 06:49:27>select @@session.tx_isolation; +------------------------+ | @@session.tx_isolation | +------------------------+ | REPEATABLE-READ | +------------------------+ 1 row in set (0.01 sec)dba@192.168.111.4 : dba_test 06:49:29>create table tmp_test_bak(id int,name varchar(64),age int,primary key(id)) engine = innodb; Query OK, 0 rows affected (0.14 sec)dba@192.168.111.4 : dba_test 06:49:34>insert into tmp_test_bak values(1,'aaa',11); Query OK, 1 row affected (0.13 sec)dba@192.168.111.4 : dba_test 06:49:41>insert into tmp_test_bak values(2,'bbb',22); Query OK, 1 row affected (0.11 sec)dba@192.168.111.4 : dba_test 06:49:41>insert into tmp_test_bak values(3,'ccc',33); Query OK, 1 row affected (0.11 sec)dba@192.168.111.4 : dba_test 06:49:42>insert into tmp_test_bak values(4,'ddd',44); Query OK, 1 row affected (0.11 sec)dba@192.168.111.4 : dba_test 06:49:42>insert into tmp_test_bak values(5,'eee',55); Query OK, 1 row affected (0.13 sec)BINLOG: root@dba:/var/log/mysql# mysqlbinlog mysql-bin.000007 |grep "tmp_test_bak" create table tmp_test_bak(id int,name varchar(64),age int,primary key(id)) engine = innodb insert into tmp_test_bak values(1,'aaa',11) insert into tmp_test_bak values(2,'bbb',22) insert into tmp_test_bak values(3,'ccc',33) insert into tmp_test_bak values(4,'ddd',44) insert into tmp_test_bak values(5,'eee',55)############################# #############################dba@192.168.111.4 : dba_test 06:49:43>set session transaction isolation level READ COMMITTED; Query OK, 0 rows affected (0.01 sec)dba@192.168.111.4 : dba_test 06:50:21>flush logs; Query OK, 0 rows affected (0.21 sec)dba@192.168.111.4 : dba_test 06:50:23>create table tmp_test(id int,name varchar(64),age int,primary key(id)) engine = innodb; Query OK, 0 rows affected (0.14 sec)dba@192.168.111.4 : dba_test 06:50:49>insert into tmp_test values(1,'aaa',11); Query OK, 1 row affected (0.13 sec)dba@192.168.111.4 : dba_test 06:50:54>insert into tmp_test values(2,'bbb',22); Query OK, 1 row affected (0.11 sec)dba@192.168.111.4 : dba_test 06:50:54>insert into tmp_test values(3,'ccc',33); Query OK, 1 row affected (0.11 sec)dba@192.168.111.4 : dba_test 06:50:54>insert into tmp_test values(4,'ddd',44); Query OK, 1 row affected (0.11 sec)dba@192.168.111.4 : dba_test 06:50:54>insert into tmp_test values(5,'eee',55); Query OK, 1 row affected (0.12 sec)BINLOG: root@pubmed2:/var/log/mysql# mysqlbinlog -vv mysql-bin.000008 |grep "tmp_test" create table tmp_test(id int,name varchar(64),age int,primary key(id)) engine = innodb #160426 18:50:54 server id 1 end_log_pos 395 Table_map: `pubmed_data`.`tmp_test` mapped to number 44 ### INSERT INTO `pubmed_data`.`tmp_test` #160426 18:50:54 server id 1 end_log_pos 597 Table_map: `pubmed_data`.`tmp_test` mapped to number 44 ### INSERT INTO `pubmed_data`.`tmp_test` #160426 18:50:54 server id 1 end_log_pos 799 Table_map: `pubmed_data`.`tmp_test` mapped to number 44 ### INSERT INTO `pubmed_data`.`tmp_test` #160426 18:50:54 server id 1 end_log_pos 1001 Table_map: `pubmed_data`.`tmp_test` mapped to number 44 ### INSERT INTO `pubmed_data`.`tmp_test` #160426 18:50:55 server id 1 end_log_pos 1203 Table_map: `pubmed_data`.`tmp_test` mapped to number 44 ### INSERT INTO `pubmed_data`.`tmp_test`
经过测试，在5.1、5.5、5.6都有这个情况，可能这个本身就不是问题。:)
总结：
除了上面说的一些条件影响binlog的记录格式外（Statement 到 Row），事务隔离也影响这binlog的记录格式行为。
