MySQL 連接數設置操作（Too many connections）及設置md5值的加密密碼

 

mysql在使用過程中，發現連接數超了~~~~

[root@linux-node1 ~]# mysql -u glance -h 192.168.1.17 -p
Enter password:
ERROR 1040 (08004): Too many connections

解決辦法，這也是centos7下修改mysql連接數的做法：
1）臨時修改
MariaDB [(none)]> show variables like "max_connections";
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 214 |
+-----------------+-------+
1 row in set (0.00 sec)
MariaDB [(none)]> set GLOBAL max_connections=1000;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> show variables like "max_connections";
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 1000 |
+-----------------+-------+
1 row in set (0.00 sec)

2）永久修改：
配置/etc/my.cnf
[mysqld]新添加一行如下參數：
max_connections=1000
重啟mariadb服務，再次查看mariadb數據庫最大連接數，可以看到最大連接數是214，並非我們設置的1000。
MariaDB [(none)]> show variables like 'max_connections';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 214 |
+-----------------+-------+
這是由於mariadb有默認打開文件數限制。可以通過配置/usr/lib/systemd/system/mariadb.service來調大打開文件數目。

配置/usr/lib/systemd/system/mariadb.service
[Service]新添加兩行如下參數：
LimitNOFILE=10000
LimitNPROC=10000

重新加載系統服務，並重啟mariadb服務
systemctl --system daemon-reload
systemctl restart mariadb.service

再次查看mariadb數據庫最大連接數，可以看到最大連接數已經是1000
MariaDB [(none)]> show variables like 'max_connections';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 1000 |
+-----------------+-------+

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mysql設置32位md5值的密文密碼

如下，設置admin用戶的密碼為"123!@#ad"
mysql> select * from admin_user;
+----+----------+--------------------------------------------------------------------+----------------------+---------------------+
| id | username | password                                                 | create_time    | update_time  |
+----+---------------+---------------------------------------------------------------+----------------------+---------------------+
|  1 | admin       | 4ad597c11755c50d00457f4420365763 |  1538979880 |  1538979880 |
+----+---------------+---------------------------------------------------------------+----------------------+---------------------+
1 row in set (0.00 sec)

mysql> update admin_user set username = 'admin',password = md5('123!@#ad') where id = 1

mysql> select * from admin_user;
+----+----------+--------------------------------------------------------------------+----------------------+---------------------+
| id | username | password                                                 | create_time    | update_time  |
+----+---------------+---------------------------------------------------------------+----------------------+---------------------+
|  1 | admin       | 0fy866r8662a70d85632u90563212687 |  1541676212  |  1541676212 |
+----+---------------+---------------------------------------------------------------+----------------------+---------------------+
1 row in set (0.00 sec)