MySQL Server variables

Server variables for MySQL

The MySQL server maintains two major classes of variables, one server variable and the other state variable. which
Server variables: Define MySQL server run characteristics
1. mysql server variables can be divided into global variables and session variables according to scope:

Global variables:

#SHOW GLOBAL VARIABLES [like ' STRING '];

#使用该命令可以显示某个服务所有的全局变量及其值

Session Variables:

#SHOW [SESSION] VARIABLES [like ' STRING ']

#使用该命令可以显示所有的服务器会话变量及其值

2, MySQL server variable according to the effective time, it can be divided into dynamic variables and static variables:

Dynamic variables: Can be modified in time, permanently saved

Static variables: passed to the mysqld through the parameters, to be permanently effective, need to be modified to write in the configuration file.

Dynamic adjustment variables are effective in the following ways:

For global variables: invalid for current session, valid for new session

For session variables: effective in time, but only for current session

3. Display server variables and their values

mysql> SELECT @ @VARIABLE_NAME;

4. Setting server variables and their values

Mysql> SET {globallsession} variable_name= ' VALUE '

State variables:
MySQL Server run statistics saved
#SHOW GLOBAL STATUS [like ' STRING ']

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MySQL Server variables