【第九課】MriaDB密碼重置和慢查詢日誌

目錄

• 一、如何進行修改MariaDB的密碼
• 二、Mariadb的慢查詢日誌

一、如何進行修改MariaDB的密碼

記得root密碼的修改方式：

[root@localhost ~]# mysqladmin -uroot -p123456 password "123123"
[root@localhost ~]# mysql -uroot -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 37
Server version: 10.1.20-MariaDB MariaDB Server

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> quit
Bye

忘記root密碼的修改方式

[root@localhost ~]# vim /etc/my.cnf.d/mariadb-server.cnf 
[mysqld]    #在mysqld段中增長skip-grant-tables，跳過受權表
server_id=1111
log-bin=mysql-bin
skip-grant-tables
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

[root@localhost ~]# systemctl restart mariadb   #重啓mariadb
[root@localhost ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 10.1.20-MariaDB MariaDB Server

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
MariaDB [mysql]> desc user;
+------------------------+-----------------------------------+------+-----+----------+-------+
| Field                  | Type                              | Null | Key | Default  | Extra |
+------------------------+-----------------------------------+------+-----+----------+-------+
| Host                   | char(60)                          | NO   | PRI |          |       |
| User                   | char(80)                          | NO   | PRI |          |       |
| Password               | char(41)                          | NO   |     |          |       |
| Select_priv            | enum('N','Y')                     | NO   |     | N        |       |
| Insert_priv            | enum('N','Y')                     | NO   |     | N        |       |
| Update_priv            | enum('N','Y')                     | NO   |     | N        |       |
| Delete_priv            | enum('N','Y')                     | NO   |     | N        |       |
| Create_priv            | enum('N','Y')                     | NO   |     | N        |       |
| Drop_priv              | enum('N','Y')                     | NO   |     | N        |       |
| Reload_priv            | enum('N','Y')                     | NO   |     | N        |       |
| Shutdown_priv          | enum('N','Y')                     | NO   |     | N        |       |
| Process_priv           | enum('N','Y')                     | NO   |     | N        |       |
| File_priv              | enum('N','Y')                     | NO   |     | N        |       |
| Grant_priv             | enum('N','Y')                     | NO   |     | N        |       |
| References_priv        | enum('N','Y')                     | NO   |     | N        |       |
| Index_priv             | enum('N','Y')                     | NO   |     | N        |       |
| Alter_priv             | enum('N','Y')                     | NO   |     | N        |       |
| Show_db_priv           | enum('N','Y')                     | NO   |     | N        |       |
| Super_priv             | enum('N','Y')                     | NO   |     | N        |       |
| Create_tmp_table_priv  | enum('N','Y')                     | NO   |     | N        |       |
| Lock_tables_priv       | enum('N','Y')                     | NO   |     | N        |       |
| Execute_priv           | enum('N','Y')                     | NO   |     | N        |       |
| Repl_slave_priv        | enum('N','Y')                     | NO   |     | N        |       |
| Repl_client_priv       | enum('N','Y')                     | NO   |     | N        |       |
| Create_view_priv       | enum('N','Y')                     | NO   |     | N        |       |
| Show_view_priv         | enum('N','Y')                     | NO   |     | N        |       |
| Create_routine_priv    | enum('N','Y')                     | NO   |     | N        |       |
| Alter_routine_priv     | enum('N','Y')                     | NO   |     | N        |       |
| Create_user_priv       | enum('N','Y')                     | NO   |     | N        |       |
| Event_priv             | enum('N','Y')                     | NO   |     | N        |       |
| Trigger_priv           | enum('N','Y')                     | NO   |     | N        |       |
| Create_tablespace_priv | enum('N','Y')                     | NO   |     | N        |       |
| ssl_type               | enum('','ANY','X509','SPECIFIED') | NO   |     |          |       |
| ssl_cipher             | blob                              | NO   |     | NULL     |       |
| x509_issuer            | blob                              | NO   |     | NULL     |       |
| x509_subject           | blob                              | NO   |     | NULL     |       |
| max_questions          | int(11) unsigned                  | NO   |     | 0        |       |
| max_updates            | int(11) unsigned                  | NO   |     | 0        |       |
| max_connections        | int(11) unsigned                  | NO   |     | 0        |       |
| max_user_connections   | int(11)                           | NO   |     | 0        |       |
| plugin                 | char(64)                          | NO   |     |          |       |
| authentication_string  | text                              | NO   |     | NULL     |       |
| password_expired       | enum('N','Y')                     | NO   |     | N        |       |
| is_role                | enum('N','Y')                     | NO   |     | N        |       |
| default_role           | char(80)                          | NO   |     |          |       |
| max_statement_time     | decimal(12,6)                     | NO   |     | 0.000000 |       |
+------------------------+-----------------------------------+------+-----+----------+-------+
46 rows in set (0.00 sec)

MariaDB [mysql]> update user set password=password("123456") where user='root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 3  Changed: 1  Warnings: 0

MariaDB [mysql]> quit;
Bye
[root@localhost ~]# vim /etc/my.cnf.d/mariadb-server.cnf 
刪除/etc/my.cnf裏面的skip-grant, 重啓服務
[root@localhost ~]# systemctl restart mariadb
[root@localhost ~]# mysql -uroot -p
Enter password: 123456
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 10.1.20-MariaDB MariaDB Server

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> quit;
Bye

二、Mariadb的慢查詢日誌

爲何要配置慢查詢日誌？

其目的是爲了幫助咱們分析MariaDB的瓶頸點，或者說是業務的瓶頸點。任何一個動態網站都會有讀取和寫入到數據庫的操做，若是其中有一個腳本或SQL語句執行特別慢，那麼帶來的現象多是用戶訪問站點時出現卡頓，或者響應較慢。那麼爲了去分析慢查詢，就能夠啓用慢查詢日誌的方式。

如何配置慢查詢？？

• （1）進入MariaDB裏面進行執行：
  • show variables like "slow%";
  • show variables like "datadir";
  • show variables like "long%";
• （2）編輯/etc/my.cnf進行配置
• （3）重啓服務
• （4）模擬慢查詢
• （5）查看慢查詢日誌

（1）進入MariaDB裏面進行執行

[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 16
Server version: 10.1.20-MariaDB MariaDB Server

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> show variables like "slow%";  #查看慢查詢相關的配置
+---------------------+--------------------+
| Variable_name       | Value              |
+---------------------+--------------------+
| slow_launch_time    | 2                  |    #慢查詢運行時間配置
| slow_query_log      | OFF                |    #是否開啓慢查詢
| slow_query_log_file | localhost-slow.log |    #慢查詢日誌文件名稱，存在於datadir中
+---------------------+--------------------+
3 rows in set (0.01 sec)

MariaDB [(none)]> show variables like "datadir";    #查看datadir路徑
+---------------+-----------------+
| Variable_name | Value           |
+---------------+-----------------+
| datadir       | /var/lib/mysql/ |
+---------------+-----------------+
1 row in set (0.00 sec)

MariaDB [(none)]> show variables like "long%";  #查詢時間配置
+-----------------+-----------+
| Variable_name   | Value     |
+-----------------+-----------+
| long_query_time | 10.000000 |
+-----------------+-----------+
1 row in set (0.00 sec)

（2）編輯/etc/my.cnf進行配置
[root@localhost ~]# vim /etc/my.cnf     #修改my.cnf配置慢查詢日誌
[mysqld]
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
slow_query_log = ON     #開啓慢查詢記錄
slow_query_log_file = /var/lib/mysql/mysql-slow.log     #配置慢查詢日誌文件路徑
long_query_time = 2     #配置查詢時間超過2s進行記錄

（3）重啓服務
[root@localhost ~]# systemctl restart mariadb

（4）模擬慢查詢
[root@localhost ~]# mysql -uroot -p     #從新登陸，運行select進行驗證記錄
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 10.1.20-MariaDB MariaDB Server

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> select sleep(5);
+----------+
| sleep(5) |
+----------+
|        0 |
+----------+
1 row in set (5.00 sec)

（5）查看慢查詢日誌
[root@localhost ~]# cat /var/lib/mysql/mysql-slow.log   #查看慢查詢日誌
/usr/libexec/mysqld, Version: 10.1.20-MariaDB (MariaDB Server). started with:
Tcp port: 0  Unix socket: /var/lib/mysql/mysql.sock
Time                 Id Command    Argument
# Time: 190218 11:43:05
# User@Host: root[root] @ localhost []
# Thread_id: 3  Schema:   QC_hit: No
# Query_time: 5.002032  Lock_time: 0.000000  Rows_sent: 1  Rows_examined: 0
# Rows_affected: 0
SET timestamp=1550461385;
select sleep(5);    #提示慢查詢的運行指令

同時，還能夠使用show processlist;和show full processlist;進行查看慢查詢隊列

show processlist; 查看全部的隊列；能夠查看數據庫中有些什麼查詢和查詢量的多少，若是查詢量超過100都會比較慢，此時就須要進行優化。

show full processlist; 和上面有什麼區別呢？若是有1個語句特別長，info列，只會顯示一部分，使用這個命令時，就能夠顯示完整的信息。

MariaDB [(none)]> show processlist;
+----+------+-----------+------+---------+------+-------+------------------+----------+
| Id | User | Host      | db   | Command | Time | State | Info             | Progress |
+----+------+-----------+------+---------+------+-------+------------------+----------+
|  3 | root | localhost | NULL | Query   |    0 | init  | show processlist |    0.000 |
+----+------+-----------+------+---------+------+-------+------------------+----------+
1 row in set (0.00 sec)

MariaDB [(none)]> show full processlist;
+----+------+-----------+------+---------+------+-------+-----------------------+----------+
| Id | User | Host      | db   | Command | Time | State | Info                  | Progress |
+----+------+-----------+------+---------+------+-------+-----------------------+----------+
|  3 | root | localhost | NULL | Query   |    0 | init  | show full processlist |    0.000 |
+----+------+-----------+------+---------+------+-------+-----------------------+----------+
1 row in set (0.00 sec)