背景

CentOS7 安装 mysql 5.7,记录一下。

官方文档:https://dev.mysql.com/doc/refman/5.7/en/installing.html

命令行安装文档:https://dev.mysql.com/doc/mysql-sles-repo-quick-guide/en/

安装方式

Linux上安装软件常见的几种方式:

源码编译

压缩包解压(一般为tar.gz)

编译好的安装包(RPM、DPKG等)

在线安装(YUM、APT等)

以上几种方式便捷性依次增加,但通用性依次下降,比如直接下载压缩包进行解压,这种方式一般需要自己做一些额外的配置工作,但只要掌握了方法,各个平台基本都适用,YUM虽然简单,但是平台受限,网络受限,必要的时候还需要增加一些特定YUM源。

几种安装方式最好都能掌握,原则上能用简单的就用简单的:YUM>RPM>tar.gz>源码

YUM

检查是否已经安装

rpm -qa|grep mysql

删除MySQL

如果不存在(上面检查结果返回空)则跳过步骤

rpm -e --nodeps xxx

我这里是空,跳过这个步骤。

查看系统版本

# cat /etc/redhat-release
CentOS Linux release 7.9.2009 (Core)

选择对应的版本进行下载,例如CentOS 7当前在官网查看最新Yum源的下载地址为:

https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm

下载:

wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm

安装

sudo rpm -Uvh mysql80-community-release-el7-3.noarch.rpm

查看是否安装成功

执行成功后会在/etc/yum.repos.d/目录下生成两个repo文件mysql-community.repo及 mysql-community-source.repo

并且通过 yum repolist 可以看到mysql相关资源

选择 mysql 版本

使用MySQL Yum Repository安装MySQL,默认会选择当前最新的稳定版本,例如通过上面的MySQL源进行安装的话,默安装会选择MySQL 8.0版本,如果就是想要安装该版本,可以直接跳过此步骤,如果不是,比如我这里希望安装MySQL5.7版本,就需要“切换一下版本”:

查看版本

查看当前MySQL Yum Repository中所有MySQL版本(每个版本在不同的子仓库中)

yum repolist all | grep mysql

切换版本

shell> sudo yum-config-manager --disable mysql80-community
shell> sudo yum-config-manager --enable mysql57-community

报错

sudo: yum-config-manager: command not found

通过

yum -y install yum-utils 

除了使用yum-config-manager之外,还可以直接编辑/etc/yum.repos.d/mysql-community.repo文件

enabled=0禁用

[mysql80-community]
name=MySQL 8.0 Community Server
baseurl=http://repo.mysql.com/yum/mysql-8.0-community/el/7/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

enabled=1启用

# Enable to use MySQL 5.7
[mysql57-community]
name=MySQL 5.7 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

安装

检查当前启用的MySQL仓库

shell> yum repolist enabled | grep mysql

我这里采用 5.7,日志如下:

# yum repolist enabled | grep mysql
mysql-connectors-community/x86_64 MySQL Connectors Community                 212
mysql-tools-community/x86_64      MySQL Tools Community                      132
mysql57-community/x86_64          MySQL 5.7 Community Server                 524

安装MySQL

命令

sudo yum install mysql-community-server

该命令会安装MySQL服务器 (mysql-community-server) 及其所需的依赖、相关组件,包括mysql-community-client、mysql-community-common、mysql-community-libs等

如果带宽不够,这个步骤时间会比较长,请耐心等待~

期间需要用户交互 2 次,不然进度不会向下走。

启动MySQL

  • 启动
sudo systemctl start mysqld.service
  • 查看状态
sudo systemctl status mysqld.service
  • 停止
sudo systemctl stop mysqld.service
  • 重启
sudo systemctl restart mysqld.service

修改密码

初始密码

MySQL第一次启动后会创建超级管理员账号root@localhost,初始密码存储在日志文件中:

sudo grep 'temporary password' /var/log/mysqld.log

日志:

2021-08-22T02:56:03.411041Z 1 [Note] A temporary password is generated for root@localhost: xxxx

修改默认密码

mysql -uroot -p

使用临时密码登录。

ALTER USER 'root'@'localhost' IDENTIFIED BY '123456';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

出现上面的提示是因为密码太简单了,解决方法如下:

  1. 使用复杂密码,MySQL默认的密码策略是要包含数字、字母及特殊字符;

  2. 如果只是测试用,不想用那么复杂的密码,可以修改默认策略,即validate_password_policy(以及validate_password_length等相关参数),使其支持简单密码的设定,具体方法可以自行百度;

  3. 修改配置文件/etc/my.cnf,添加validate_password=OFF,保存并重启MySQL

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)

此处不建议这么干,还是使用略微复杂一点的密码。

这一步必须修改,否则无法继续使用。

允许root远程访问

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION;
mysql> FLUSH PRIVILEGES;

这个可以不开启,根据个人需求而定。

设置开机启动

systemctl enable mysqld
systemctl daemon-reload

设置编码

  • 查看编码
mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name LIKE 'collation%';

如下:

+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | latin1                     |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | latin1                     |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
| collation_connection     | utf8_general_ci            |
| collation_database       | latin1_swedish_ci          |
| collation_server         | latin1_swedish_ci          |
+--------------------------+----------------------------+
  • 修改配置文件

编辑 /etc/my.cnf

原始配置为:

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

调整配置如下:

[mysql]
# 设置mysql客户端默认字符集
default-character-set=utf8mb4
 
[mysqld]
# 原始配置部分
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

# 设置3306端口
port=3306
# 允许最大连接数
max_connections=20
# 服务端使用的字符集默认为8比特编码的latin1字符集
character-set-server=utf8mb4
# 创建新表时将使用的默认存储引擎
default-storage-engine=INNODB
 
collation-server=utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'

character-set-client-handshake=FALSE
explicit_defaults_for_timestamp=true

lower_case_table_names=1

[client]
default-character-set=utf8mb4
  • 重启 mysql 服务
sudo systemctl restart mysqld.service
  • 查看配置
mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name LIKE 'collation%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8mb4                    |
| character_set_connection | utf8mb4                    |
| character_set_database   | utf8mb4                    |
| character_set_filesystem | binary                     |
| character_set_results    | utf8mb4                    |
| character_set_server     | utf8mb4                    |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
| collation_connection     | utf8mb4_unicode_ci         |
| collation_database       | utf8mb4_unicode_ci         |
| collation_server         | utf8mb4_unicode_ci         |
+--------------------------+----------------------------+

大小写敏感

linux 系统

mysql是通过lower_case_table_names变量来处理大小写问题的。

首先查询该变量

mysql在Linux下数据库名、表名、列名、表别名大小写规则如下:

1、数据库名与表名严格区分大小写;

2、表别名严格区分大小写;

3、列名和列别名在所有情况下都是忽略大小写的;

4、变量名也是严格区分大小写的;

mysql在windows下都不区分大小写。

查看大小写敏感

show Variables like '%table_names';

结果如下:

mysql> show Variables like '%table_names';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| lower_case_table_names | 0     |
+------------------------+-------+

lower_case_table_names=0(默认)区分大小写,lower_case_table_names=1表示不区分大小写

更改解决

修改 /etc/my.cnf ,在 [mysqld] 后边添加 lower_case_table_names=1 重启mysql服务。

vi /etc/my.cnf

重启服务:

sudo systemctl restart mysqld.service

重新后再确认下即可。

mysql 自动登录脚本

脚本

#!/usr/bin/expect

spawn mysql -h 127.0.0.1 -uroot -p 
set timeout 100
expect "Enter password:"
send "password\r"
interact

说明如下:

#!/usr/bin/expect 就是在上面获取的expect的安装路径,expect类似于一个sh

spawn 是expect的语句,执行命令前都要加这句

expect “Enter password:” 这句要加上,不加上会报错

send “password\r” 密码中如果有%等关键字,需要加转义符号/

interact 代表执行完留在远程控制台

执行报错

-bash: ./log.sh: /usr/bin/expect: bad interpreter: No such file or directory

网上说的比较多的原因就是 windows 和 unix 系统的编码不同导致。

编码问题?

查看文件编码

vi 文件执行,执行下面的命令

:set ff 或 :set fileformat

结果如下:

fileformat=unix

发现编码是 unix,那就是没有安装的问题

安装 expect 命令

yum install tcl-devel
yum install expect

重新尝试后,问题解决。

mysql 内存占用过大的问题

内存占用

查看内存使用情况

free -h

查看谁在占用?

top

看了下 mysql 的内存占用大概 20% 左右,还能接受。

配置调整

解决思路很明确,就是修改配置文件 /etc/my.cnf,以下是我修改后的配置,大家请参考。

[mysqld]
lower_case_table_names=1
character-set-server=utf8
max_connections = 300
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES 

key_buffer_size = 16k
max_allowed_packet = 1M
thread_stack = 64k
sort_buffer_size = 64k
net_buffer_length = 2k
performance_schema_max_table_instances = 12500
table_open_cache_instances = 1
eq_range_index_dive_limit = 10
innodb_buffer_pool_dump_at_shutdown = OFF
innodb_buffer_pool_load_at_startup = OFF
innodb_checksum_algorithm = innodb
innodb_file_format = Antelope
innodb_file_format_max = Antelope
innodb_large_prefix = OFF
innodb_purge_threads = 1
innodb_strict_mode = OFF
max_seeks_for_key = 4294967295
max_write_lock_count = 4294967295
myisam_max_sort_file_size = 2146435072
performance_schema_accounts_size = 100
performance_schema_hosts_size = 100
performance_schema_max_cond_instances = 6900
performance_schema_max_file_classes = 50
performance_schema_max_mutex_instances = 21000
performance_schema_max_rwlock_instances = 10800
performance_schema_max_table_handles = 4000
performance_schema_max_thread_instances = 2100
performance_schema_setup_actors_size = 100
performance_schema_setup_objects_size = 100
performance_schema_users_size = 100
sync_binlog = 0
innodb_buffer_pool_size = 8M
innodb_log_buffer_size = 1M

上面的配置我是参考我本地的5.6.25配置修改的,因为我发现我本地的这个版本占用内存非常小。当然在windows上和linux上或许是有区别的。修改完之后mysql内存占用率下降到了26%左右,也就是占用260兆左右,现在我的剩余内存能保持在300兆左右了。

也是经过这个事情我才发现安装在linux上的mysql要比在windows上更吃内存,起初我以为是阿里云服务器的原因,查看了一下其他linux上的mysql占用内存情况也都在600兆左右,只不过其他服务器内存配置都挺高所以感觉不出来。

如果遇到问题请查看mysql的日志文件/var/log/mysqld.log,里面的错误记录如[ERROR] unknown variable ‘have_crypt=NO’,这就表示你的版本没有have_crypt这个变量,删掉即可。

centos7 yum mysql 5.7 安装笔记(2021-12-20)

配置 yum 源

去 MySQL 官网下载 YUM 的 RPM 安装包,http://dev.mysql.com/downloads/repo/yum/

(1)下载

$   sudo wget https://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm

(2)安装 mysql 源

$   sudo yum localinstall mysql57-community-release-el7-11.noarch.rpm

(3)检查 mysql 源是否安装成功

$   yum repolist enabled | grep "mysql.*-community.*"

如下:

mysql-connectors-community/x86_64   MySQL Connectors Community               221
mysql-tools-community/x86_64        MySQL Tools Community                    135
mysql57-community/x86_64            MySQL 5.7 Community Server               544

安装 mysql

$   sudo yum install -y mysql-community-server

启动 mysql 服务

在 CentOS 7 下,新的启动/关闭服务的命令是 systemctl start|stop

(1)启动

$   sudo systemctl start mysqld

(2)状态查看

$   sudo systemctl status mysqld

日志如下:

mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2021-12-20 14:49:30 CST; 1min 11s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 24492 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
  Process: 24433 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 24496 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─24496 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

Dec 20 14:49:25 VM-12-8-centos systemd[1]: Starting MySQL Server...
Dec 20 14:49:30 VM-12-8-centos systemd[1]: Started MySQL Server.

设置开机启动

$ sudo systemctl enable mysqld

重载所有修改过的配置文件

$ sudo systemctl daemon-reload

修改 root 本地账户密码

(1)临时默认密码

mysql 安装完成之后,生成的默认密码在 /var/log/mysqld.log 文件中。

使用 grep 命令找到日志中的密码。

$   grep 'temporary password' /var/log/mysqld.log

如下:

2021-12-20T06:49:26.697576Z 1 [Note] A temporary password is generated for root@localhost: XXXXXXXX

(2)登录修改

使用临时密码登录。

$   mysql -uroot -p

修改密码命令:

$   ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPassword!'; 

或者:

$   set password for 'root'@'localhost'=password('MyNewPass4!'); 

注意:

mysql 5.7 默认安装了密码安全检查插件(validate_password),默认密码检查策略要求密码必须包含:大小写字母、数字和特殊符号,并且长度不能少于8位。

否则会提示 ERROR 1819 (HY000): Your password does not satisfy the current policy requirements 错误。

查看 MySQL官网密码详细策略

配置文件调整

mysql 安装后默认不支持中文,需要修改编码。

修改 /etc/my.cnf 配置文件。

可参考的配置如下:

[mysql]
# 设置mysql客户端默认字符集
default-character-set=utf8mb4
 
[mysqld]
# 原始配置部分
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

# 设置3306端口
port=3306
# 允许最大连接数
max_connections=20
# 服务端使用的字符集默认为8比特编码的latin1字符集
character-set-server=utf8mb4
# 创建新表时将使用的默认存储引擎
default-storage-engine=INNODB
 
collation-server=utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'

character-set-client-handshake=FALSE
explicit_defaults_for_timestamp=true

# mysql 大小写敏感
lower_case_table_names=1

[client]
default-character-set=utf8mb4
  • 重启 mysql 服务
sudo systemctl restart mysqld.service
  • 登录查看配置
mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name LIKE 'collation%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8mb4                    |
| character_set_connection | utf8mb4                    |
| character_set_database   | utf8mb4                    |
| character_set_filesystem | binary                     |
| character_set_results    | utf8mb4                    |
| character_set_server     | utf8mb4                    |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
| collation_connection     | utf8mb4_unicode_ci         |
| collation_database       | utf8mb4_unicode_ci         |
| collation_server         | utf8mb4_unicode_ci         |
+--------------------------+----------------------------+

参考资料

CentOS安装MySQL详解

Linux执行shell出现错误bad interpreter: No such file or directory解决方法

CentOS上mysql占用内存过大之解决

CentOS 7 下 Yum 安装 MySQL 5.7

CentOS 7 下 MySQL 5.7 的安装与配置