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  • MySQL read_only 与 super_read_only 之间的关系

    read_only 表示是否允许普通用户写入。如果为on,表示禁止普通用户写入。

    super_read_only 表示是否禁止超级用户写入,包括普通用户,即针对所有用户。
    默认关闭。

    如果打开 super_read_only,则read_only会自动打开。

    如果关闭 read_only,则 super_read_only 会自动关闭。

    下面做下测试。

    当super_read_only = 0, read_only=0,设置super_read_only=1

    查看当前值:

    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           0 |
    +-------------------+-------------+
    1 row in set (0.01 sec)
    

    设置super_read_only=1之后,查看read_only的变化。

    >set global super_read_only=1;
    Query OK, 0 rows affected (0.00 sec)
    
    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 1 |           1 |
    +-------------------+-------------+
    1 row in set (0.01 sec)
    

    read_only变为1。

    超级用户设置为只读后,自然普通用户也会设置只读。

    当super_read_only=0, read_only=1,设置 super_read_only=1

    查看当前值:

    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           1 |
    +-------------------+-------------+
    1 row in set (0.00 sec)
    

    设置 super_read_only=1后, 查看read_only 变化。

    >set global super_read_only=1;
    Query OK, 0 rows affected (0.00 sec)
    
    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 1 |           1 |
    +-------------------+-------------+
    1 row in set (0.00 sec)
    

    read_only无变化。

    当super_read_only=1, read_only=0

    不存在这种情况。

    当super_read_only=1, read_only=1,设置super_read_only = 0

    查看当前值:

    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 1 |           1 |
    +-------------------+-------------+
    1 row in set (0.00 sec)
    

    设置super_read_only = 0之后, 查看read_only变化。

    >set global super_read_only=0;
    Query OK, 0 rows affected (0.01 sec)
    
    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           1 |
    +-------------------+-------------+
    1 row in set (0.00 sec)
    

    当super_read_only = 0, read_only=0,设置read_only=1

    查看当前值:

    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           0 |
    +-------------------+-------------+
    1 row in set (0.01 sec)
    

    设置read_only=1之后,查看super_read_only 有无变化。

    >set global read_only=1;
    Query OK, 0 rows affected (0.00 sec)
    
    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           1 |
    +-------------------+-------------+
    1 row in set (0.00 sec)
    

    当super_read_only = 1, read_only=0

    不存在这种情况。

    当super_read_only = 0, read_only=1,设置 read_only=0

    查看当前值:

    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           1 |
    +-------------------+-------------+
    1 row in set (0.00 sec)
    

    设置 read_only=0后,查看super_read_only有无变化。

    >set global read_only=0;
    Query OK, 0 rows affected (0.00 sec)
    
    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           0 |
    +-------------------+-------------+
    1 row in set (0.01 sec)
    

    super_read_only变为 0。

    普通用户关闭只读,超级用户的只读(也包括普通用户)也自然会关闭只读。

    当super_read_only = 1, read_only=1,设置read_only=0

    查看当前值:

    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 1 |           1 |
    +-------------------+-------------+
    1 row in set (0.01 sec)
    

    设置read_only=0之后,查看 super_read_only的变化。

    >set global read_only=0;
    Query OK, 0 rows affected (0.00 sec)
    
    >select @@super_read_only, @@read_only;
    +-------------------+-------------+
    | @@super_read_only | @@read_only |
    +-------------------+-------------+
    |                 0 |           0 |
    +-------------------+-------------+
    1 row in set (0.01 sec)
    

    super_read_only变为 0。

    总结

    关于 read_only 与 super_read_only之间的关系,实际上从其定义就可以明白。

    基础很重要。

    Just try, don't shy.
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  • 原文地址:https://www.cnblogs.com/lanyangsh/p/14391471.html
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