2019-02-15笔记—MariaDB重置密码、慢查询日志

mariadb重置密码

1. 修改一般用户的密码

MariaDB [mysql]>  use mysql;
MariaDB [mysql]> update user set authentication_string=password("bbs?DXG123") where User='bbs' and host='localhost';

2. 修改root密码（知道原来root密码的情况）

mysqladmin -uroot -proot password "root"

3. 修改root密码（不知道原来root密码的情况）

[root@linux2019 ~]# vi /etc/my.cnf
skip-grant

[root@linux2019 ~]# /etc/init.d/mysqld restart
[root@linux2019 ~]# mysql -uroot    #此时不需要输入密码可以直接登陆mariadb
MariaDB [(none)]> use mysql;
MariaDB [mysql]> update user set authentication_string=password("root") where User='root' and host='localhost';
MariaDB [mysql]> exit;
[root@linux2019 ~]# vi /etc/my.cnf  #删除之前增加的配置
#skip-grant
[root@linux2019 ~]# /etc/init.d/mysqld restart

PS：mysql/mariadb在新版本里面把密码字段存到了authentication_string字段里，老版本还是在password字段里

MariaDB慢查询日志

类似于php-fpm配置里面的slow日志，可以帮助分析mariadb的瓶颈

配置

#先查看当前配置情况
MariaDB [(none)]> show variables like 'slow%';
+---------------------+--------------------+
| Variable_name       | Value              |
+---------------------+--------------------+
| slow_launch_time    | 2                  |
| slow_query_log      | OFF                |
| slow_query_log_file | linux2019-slow.log |
+---------------------+--------------------+
3 rows in set (0.002 sec)

MariaDB [(none)]> show variables like 'datadir%';
+---------------+--------------+
| Variable_name | Value        |
+---------------+--------------+
| datadir       | /data/mysql/ |
+---------------+--------------+
1 row in set (0.002 sec)

MariaDB [(none)]> show variables like 'long%';
+-----------------+-----------+
| Variable_name   | Value     |
+-----------------+-----------+
| long_query_time | 10.000000 |
+-----------------+-----------+
1 row in set (0.002 sec)

[root@linux2019 ~]# vi /etc/my.cnf
slow_query_log = ON
slow_query_log_file = /data/mysql/linux2019-slow.log
long_query_time = 2
[root@linux2019 ~]# /etc/init.d/mysqld restart

测试

MariaDB [(none)]> select sleep(5);  #模拟慢查询
+----------+
| sleep(5) |
+----------+
|        0 |
+----------+
1 row in set (5.001 sec)

MariaDB [(none)]> exit
Bye
[root@linux2019 ~]# cat /data/mysql/linux2019
linux2019.pid       linux2019-slow.log  
[root@linux2019 ~]# cat /data/mysql/linux2019-slow.log 
/usr/local/mysql/bin/mysqld, Version: 10.3.11-MariaDB-log (MariaDB Server). started with:
Tcp port: 0  Unix socket: /tmp/mysql.sock
Time		    Id Command	Argument
# Time: 190214 11:46:40
# User@Host: root[root] @ localhost []
# Thread_id: 9  Schema:   QC_hit: No
# Query_time: 5.000585  Lock_time: 0.000000  Rows_sent: 1  Rows_examined: 0
# Rows_affected: 0  Bytes_sent: 63
SET timestamp=1550116000;
select sleep(5);

PS

• show processlist; #查看查询队列
• show full processlist; #详细显示
• mysql -uroot -proot -e “show processlist” #-e选项可以让sql语句直接在linux系统执行，不用登陆到数据库