概念：

binlog format有三種形式：Statement、Mixed、Row，具體的信息可以自行到網上搜查。

分析（本文碰到的案例）：

查看MySQL binlog format

[email protected] : dba_test 02:33:39>show variables like ‘binlog_format%‘;                                                                                                   +---------------+-------+| Variable_name | Value |+---------------+-------+| binlog_format | MIXED |+---------------+-------+
 

測試語句：

[email protected] : 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)

[email protected] : dba_test 02:24:23>insert into tmp_test values(1,‘aaa‘,11);
 
Query OK, 1 row affected (0.02 sec)

[email protected] : dba_test 02:25:17>insert into tmp_test values(2,‘bbb‘,22);
Query OK, 1 row affected (0.02 sec)

[email protected] : dba_test 02:25:23>insert into tmp_test values(3,‘ccc‘,33);
Query OK, 1 row affected (0.01 sec)

[email protected]
 
 : dba_test 02:25:28>insert into tmp_test values(4,‘ddd‘,44);
Query OK, 1 row affected (0.01 sec)

[email protected] : dba_test 02:25:34>insert into tmp_test values(5,‘eee‘,55);
Query OK, 1 row affected (0.01 sec)

[email protected] : 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)

[email protected] : 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)

[email protected] : dba_test 02:26:31>insert into tmp_test_bak select * from tmp_test;   ###記錄成了Row模式Query OK, 5 rows affected (0.03 sec)
Records: 5  Duplicates: 0  Warnings: 0

Binlog 記錄圖：

問題來了，我想要出來的binlog format是Statement，而不是Row。而一條insert into tb select * from ta的簡單語句在Mixed模式下記錄了Row模式的binlog。原因是什麽？

首先確實在一些特定的情況下，Mixed會被轉換成Row模式：

. 當 DML 語句更新一個 NDB 表時；
. 當函數中包含 UUID() 時；
. 2 個及以上包含 AUTO_INCREMENT 字段的表被更新時；
. 執行 INSERT DELAYED 語句時；
. 用 UDF 時；
. 視圖中必須要求運用 row 時，例如建立視圖時使用了 UUID() 函數；

上面來自網絡，有興趣的可以自己測試測試。而對於本文中的sql，符合不了上面的條件，但binlog也記錄成了Row格式。所以還是很奇怪為什麽binlog格式被轉換了，日常工作的時候有遇到過執行一條sql，會報一個warning：

Warning: Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT

難道因為這個導致轉換的？因為上面的SQL可以重現，沒有報warning，所以這個情況排除。根據經驗想到了一個參數：innodb_locks_unsafe_for_binlog，看到裏面講到事務隔離級別，那就看看隔離級別的情況：

[email protected] : dba_test 05:46:56>select @@global.tx_isolation;+-----------------------+| @@global.tx_isolation |+-----------------------+| READ-COMMITTED        |+-----------------------+1 row in set (0.01 sec)

[email protected] : dba_test 06:36:45>select @@session.tx_isolation;+------------------------+| @@session.tx_isolation |+------------------------+| READ-COMMITTED         |+------------------------+1 row in set (0.01 sec)

看到隔離級別是提交讀，即不可重復讀。把事務隔離級別設置成默認的 REPEATABLE READ：

[email protected] : dba_test 06:41:02>set session transaction isolation level REPEATABLE READ;                                                                              
Query OK, 0 rows affected (0.14 sec)

[email protected] : dba_test 06:41:42>select @@session.tx_isolation;+------------------------+| @@session.tx_isolation |+------------------------+| REPEATABLE-READ        |+------------------------+1 row in set (0.00 sec)

再執行測試裏的SQL，發現這時候Mixed的binlog記錄了Statement格式，正常了，符合預期了。難道就是這個事務隔離級別的問題引起的？在手冊裏發現了這句：

NoteIn 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.

展開可以看例子：

View Code

經過測試，在5.1、5.5、5.6都有這個情況，可能這個本身就不是問題。:)

MySQL Binlog Mixed模式記錄成Row格式