mysql 从库设置read-only 对super权限的用户无效的问题

由于在测试mysql主从读写分离的时候，用root用户设置从库为read-only ，但是重启生效后发现，root用户照样可以进行update insert ，此时root用有all privilege权限，包括super（管理）权限

测试单独回收revoke root的super权限后再试，发现root此时 已经不能写操作了

因此在给普通用户，或区分读写分离用户时，注意要回收super权限，否则对read-only无效。

另外为了防止普通用户对从库进行插入，在给用户分配权限时要回收super权限

下面是引用网上一篇文章做例子：

配置：

[root@Slave-Mysql data]# grep read-only /etc/my.cnf
read-only

试验过程：

主库授权ALL

mysql> grant all on *.* to 'imbyrd'@'localhost' identified by 'admin';

从库测试：

[root@Slave-Mysql data]# /usr/local/mysql/bin/mysql -uimbyrd -p'admin'
mysql> use hitest;
mysql> insert into test(id,name) values(14,'fo');
Query OK, 1 row affected (0.14 sec)

主库授权select,insert,update,delete

mysql> REVOKE all ON *.* FROM 'imbyrd'@'localhost';
mysql> grant select,insert,update,delete on *.* to 'imbyrd'@'localhost' identified by 'admin';
mysql> show grants for imbyrd@'localhost';
+----------------------------------------------------------------------------------------------------------------------------------------+
| Grants for imbyrd@localhost |
+----------------------------------------------------------------------------------------------------------------------------------------+
| GRANT SELECT, INSERT, UPDATE, DELETE ON *.* TO 'imbyrd'@'localhost' IDENTIFIED BY PASSWORD '*4ACFE3202A5FF5CF467898FC58AAB1D615029441' |
+----------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

从库测试：

mysql> use hitest;
mysql> insert into test(id,name) values(16,'dddd');
ERROR 1290 (HY000): The MySQL server is running with the --read-only option so it cannot execute this statement

主库配置：

mysql> grant all on *.* to 'imbyrd'@'localhost' identified by 'admin';
mysql> show grants for imbyrd@'localhost'＼G
*************************** 1. row ***************************
Grants for imbyrd@localhost: GRANT ALL PRIVILEGES ON *.* TO 'imbyrd'@'localhost' IDENTIFIED BY PASSWORD '*4ACFE3202A5FF5CF467898FC58AAB1D615029441'
1 row in set (0.00 sec)
mysql> REVOKE SUPER ON *.* FROM 'imbyrd'@'localhost';
mysql> show grants for imbyrd@'localhost'＼G
*************************** 1. row ***************************
Grants for imbyrd@localhost: GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, RELOAD, SHUTDOWN, PROCESS, FILE, REFERENCES, INDEX, ALTER, SHOW DATABASES, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, REPLICATION SLAVE, REPLICATION CLIENT, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, CREATE USER, EVENT, TRIGGER, CREATE TABLESPACE ON *.* TO 'imbyrd'@'localhost' IDENTIFIED BY PASSWORD '*4ACFE3202A5FF5CF467898FC58AAB1D615029441'
1 row in set (0.00 sec)

从库测试：

[root@Slave-Mysql data]# /usr/local/mysql/bin/mysql -uimbyrd -p'admin'
mysql> use hitest;
mysql> insert into test(id,name) values(23,'fddf');
ERROR 1290 (HY000): The MySQL server is running with the --read-only option so it cannot execute this statement

结论：当用户权限中没有SUPER权限(ALL权限是包括SUPER的)时，从库的read-only生效！