MySQL之performance_schema數據庫的max變量含義

1.max_connections

    List-1 大致意思是MySQL容許的最大鏈接

mysql> select * from global_variables where variable_name like "max_connections";
+-----------------+----------------+
| VARIABLE_NAME   | VARIABLE_VALUE |
+-----------------+----------------+
| max_connections | 600            |
+-----------------+----------------+
1 row in set (0.00 sec)

2.max_user_connections

    List-2 大致意思是一個用戶鏈接到數據庫的最大鏈接數，爲0應該是表示不限制，設置這個變量的值能夠防止一個用戶用完全部數據庫容許的最大鏈接。

mysql> select * from global_variables where variable_name like "max_user_connections";
+----------------------+----------------+
| VARIABLE_NAME        | VARIABLE_VALUE |
+----------------------+----------------+
| max_user_connections | 0              |
+----------------------+----------------+
1 row in set (0.00 sec)

3.max_connect_errors

    List-3

mysql> select * from global_variables where variable_name like "max_connect_errors";
+--------------------+----------------+
| VARIABLE_NAME      | VARIABLE_VALUE |
+--------------------+----------------+
| max_connect_errors | 100            |
+--------------------+----------------+
1 row in set (0.01 sec)

    此值爲100時，意味着若是某一客戶端嘗試鏈接此MySQL服務器，可是失敗（如密碼錯誤等等）100次，則MySQL會無條件強制阻止此客戶端鏈接。