mysql的autocommit(自動提交)默認是開啓,其對mysql的性能有一定影響。
舉個例子來說:
如果你插入了1000條數據,mysql會commit1000次的;
如果我們把autocommit關閉掉,通過程序來控制,只要一次commit就可以了。
- set設置autocommit
mysql> set global init_connect="set autocommit=0"; //提示你用權限更高的財戶來設置
ERROR 1227 (42000): Access denied; you need (at least one of) the SUPER privilege(s) for this operation
mysql> set autocommit=0;
Query OK, 0 rows affected (0.00 sec)
mysql> select @@autocommit; //查看一下autocommit的設置
+--------------+
| @@autocommit |
+--------------+
| 0 |
+--------------+
1 row in set (0.00 sec)
- 列表內容
修改mysql的配置文件my.cnf來設置autocommit
[mysqld]
init_connect='SET autocommit=0' //在mysqld裏面加上這些內容
注意: 用第二種方法設置時,連接mysql用戶的權限不能大於啓動mysql的用戶的權限,不然init_connect=’SET autocommit=0’根本不會啓作用,也不會報任何錯誤。
例子:
zhangy@ubuntu:~$ mysql -umysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.2-m2-log Source distribution
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select @@autocommit; //mysql是啓動用戶,關閉autocommit成功
+--------------+
| @@autocommit |
+--------------+
| 0 |
+--------------+
1 row in set (0.00 sec)
mysql> Ctrl-C -- exit!
Aborted
zhangy@ubuntu:~$ mysql -uroot
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.5.2-m2-log Source distribution
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select @@autocommit; //用root財戶啓動,不成功。
+--------------+
| @@autocommit |
+--------------+
| 1 |
+--------------+
1 row in set (0.00 sec)
這個會不會是mysql的bug呢?
網上相關部分內容如下:
If a user has SUPER privilege, init_connect will not execute
(otherwise if init_connect will a wrong query no one can connect to server).
Note, if init_connect is a wrong query, the connection is closing without any errors
and next command will clause ‘lost connection’ error.
其中:
If a user has SUPER privilege, init_connect will not execute。
如果用戶有更高級的權限,init_connect根本不會執行。
來源: