mysql的运维与优化

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#数据库

本文详细介绍了MySQL数据库的安装过程，包括通过YUM安装MariaDB、配置安全设置以及创建数据库和数据表。此外，还讲解了数据库的备份与恢复方法，以及如何授权用户访问数据库。在数据库优化部分，提到了修改配置文件以提升性能，并解释了相关参数的作用。

1. MySQL运维

（1）安装数据库

配置本地YUM安装源，将提供的gpmall-repo文件上传至/opt目录，创建local.repo文件，示例代码如下：（若使用的是VMware安装的CentOS 7.2系统，自带的CentOS.repo文件不要移除。若使用的是OpenStack中的centos7.2qcow2镜像需要将自带的CentOS.repo文件移除。）

[root@localhost ~]# vi /etc/yum.repos.d/yum.repo

[mariadb]

name=mariadb

baseurl=file:///opt/mariadb_yum/

gpgcheck=0

enabled=1

[root@localhost ~]# yum install -y mariadb mariadb-server

[root@localhost ~]# systemctl start mariadb

[root@localhost ~]# mysql_secure_installation

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB

      SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!



In order to log into MariaDB to secure it, we'll need the current

password for the root user.  If you've just installed MariaDB, and

you haven't set the root password yet, the password will be blank,

so you should just press enter here.



Enter current password for root (enter for none):

OK, successfully used password, moving on...



Setting the root password ensures that nobody can log into the MariaDB

root user without the proper authorisation.



Set root password? [Y/n] y

New password:

Re-enter new password:

Password updated successfully!

Reloading privilege tables..

 ... Success!



By default, a MariaDB installation has an anonymous user, allowing anyone

to log into MariaDB without having to have a user account created for

them.  This is intended only for testing, and to make the installation

go a bit smoother.  You should remove them before moving into a

production environment.



Remove anonymous users? [Y/n] y

 ... Success!



Normally, root should only be allowed to connect from 'localhost'.  This

ensures that someone cannot guess at the root password from the network.



Disallow root login remotely? [Y/n] n

 ... skipping.



By default, MariaDB comes with a database named 'test' that anyone can

access.  This is also intended only for testing, and should be removed

before moving into a production environment.



Remove test database and access to it? [Y/n] y

 - Dropping test database...

 ... Success!

 - Removing privileges on test database...

 ... Success!



Reloading the privilege tables will ensure that all changes made so far

will take effect immediately.



Reload privilege tables now? [Y/n] y

 ... Success!



Cleaning up...



All done!  If you've completed all of the above steps, your MariaDB

installation should now be secure.



Thanks for using MariaDB!

（2）创建数据库

创建一个名称为“test”数据库。命令如下所示：

[root@mysql ~]# mysqladmin -uroot -p000000 create test

在“test”数据库中创建一个名为“tables”数据表。命令如下所示：

MariaDB [(none)]> use test;

Database changed

MariaDB [test]> CREATE TABLE IF NOT EXISTS `tables`(

`tables_id` INT UNSIGNED AUTO_INCREMENT,

             `tables_title` VARCHAR(100) NOT NULL,

             `tables_author` VARCHAR(40) NOT NULL,

             `tables_date` DATE,

             PRIMARY KEY ( `tables_id` )

)ENGINE=InnoDB DEFAULT CHARSET=utf8;

Query OK, 0 rows affected (0.067 sec)

MariaDB [test]> show tables;

+----------------+

| Tables_in_test |

+----------------+

| tables         |

+----------------+

1 row in set (0.001 sec)

（3）数据库备份

导出整个数据库，命令如下所示。

[root@mysql ~]# mysqldump -uroot -p000000 test > test.sql

[root@mysql ~]# ls

test.sql

导出一个表，命令如下所示：

[root@mysql ~]# mysqldump -uroot -p000000 test tables > test_tables.sql

[root@mysql ~]# ls

test.sql  test_tables.sql

删除test数据库进行导入测试，用mysqldump备份的文件是一个可以直接导入的SQL脚本。有两种方法可以将数据导入，一种用msql命令，把数据库文件恢复到指定的数据库，命令如下所示：

[root@mysql ~]# mysqladmin -uroot -p000000 drop test     

Dropping the database is potentially a very bad thing to do.

Any data stored in the database will be destroyed.



Do you really want to drop the 'test' database [y/N] y

Database "test" dropped

[root@mysql ~]# mysql -uroot -p000000

Welcome to the MariaDB monitor.  Commands end with ; or \g.

Your MariaDB connection id is 26

Server version: 10.3.18-MariaDB-log MariaDB Server



Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.



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



MariaDB [(none)]> create database test;

Query OK, 1 row affected (0.000 sec)



MariaDB [(none)]> quit

Bye

[root@mysql ~]# mysql -uroot -p000000 test < test.sql

第二种，可以使用source语句方法导入数据库，把数据库文件恢复到指定的数据库，命令如下所示：

[root@mysql ~]# mysqladmin -uroot -p000000 drop test      

Dropping the database is potentially a very bad thing to do.

Any data stored in the database will be destroyed.



Do you really want to drop the 'test' database [y/N] y

Database "test" dropped

[root@mysql ~]# mysql -uroot -p000000

Welcome to the MariaDB monitor.  Commands end with ; or \g.

Your MariaDB connection id is 30

Server version: 10.3.18-MariaDB-log MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.



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



MariaDB [(none)]> create database test;

Query OK, 1 row affected (0.027 sec)



MariaDB [(none)]> use test             

Database changed

MariaDB [test]> source /root/test.sql;

（4）添加用户并授权

授权root用户可以在任何节点访问test数据库下所有表，“%”代表所有节点机器，命令如下所示：

MariaDB [(none)]> GRANT ALL PRIVILEGES ON test.* TO 'root'@'%' IDENTIFIED BY '000000' ;

Query OK, 0 rows affected (0.001 sec)

MariaDB [(none)]> GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost' IDENTIFIED BY '000000' ;                                

Query OK, 0 rows affected (0.001 sec)

添加root用户对test数据库授增、删、改、查的权限，命令如下所示：

MariaDB [(none)]> GRANT SELECT,INSERT,DELETE,UPDATE ON test.* TO 'root'@'%' IDENTIFIED BY '000000' ;

Query OK, 0 rows affected (0.001 sec)

2. MySQL数据库优化

修改数据库配置文件，添加参数，命令如下所示：

# vi /etc/my.cnf

在文件中添加以下命令，优化数据库：

[mysqld]

thread_concurrency = 64 #CPU核数 * 2

max_connections=1500 #最大连接（用户）数。每个连接MySQL的用户均算作一个连接

max_connect_errors=30 #最大失败连接限制

bulk_insert_buffer_size = 32M #批量插入数据缓存大小

query_cache_type=1 #查询缓存  (0 = off、1 = on、2 = demand)

query_cache_size = 64M #指定mysql查询缓冲区大小

max_allowed_packet = 128M #通信缓冲大小

read_buffer_size = 8M #顺序读取数据缓冲区使用内存

read_rnd_buffer_size = 32M #随机读取数据缓冲区使用内存

参数优化解析，见表3-20-2。

表3-20-2 参数优化命令解析

命令	解析
thread_concurrency	并发线程数，建议为CPU核心数乘以2
max_connections	最大连接（用户）数。每个连接MySQL的用户均算作一个连接
max_connect_errors	最大失败连接限制
bulk_insert_buffer_size	批量插入数据缓存大小，可以有效提高写入效率，默认为8 MB
query_cache_type	控制着查询缓存功能的开启的关闭。0时表示关闭，1时表示打开，2表示只要select 中明确指定SQL_CACHE才缓存
query_cache_size	指定MySQL查询缓冲区的大小，用来缓冲select的结果，并在下一次同样查询的时候不再执行查询而直接返回结果，根据Qcache_lowmem_prunes的大小，来查看当前的负载是否足够高，在数据库写入量或是更新量也比较大的系统，该参数不适合分配过大。而且在高并发，写入量大的系统，建议把该功能禁掉。属重点优化参数（主库增删改-MyISAM）
max_allowed_packet	设定在网络传输中一次可以传输消息的最大值，系统默认为1 MB，最大可1 GB
read_buffer_size	来做MYISAM表全表扫描的缓冲大小，对表进行顺序扫描的请求将分配一个读入缓冲区，MySQL会为它分配一段内存缓冲区。read_buffer_size变量控制这一缓冲区的大小。如果对表的顺序扫描请求非常频繁，并且用户认为频繁扫描进行得太慢，可以通过增加该变量值以及内存缓冲区大小提高其性能
read_rnd_buffer_size	随机读（查询操作）缓冲区大小。当按任意顺序读取行时(例如，按照排序顺序)，将分配一个随机读缓存区。进行排序查询时，MySQL会首先扫描一遍该缓冲，以避免磁盘搜索，提高查询速度，如果需要排序大量数据，可适当调高该值。但MySQL会为每个客户连接发放该缓冲空间，所以应尽量适当设置该值，以避免内存开销过大