CentOS下MySQL8.0的超详细的安装及配置文档

操作系统环境：centos linux release 7.7.1908 (Core)

基础环境配置

关闭SeLinux及防火墙

sed -i "s/SELINUX=enforcing/SELINUX=disabled/" /etc/selinux/config
setenforce 0 
​
systemctl stop firewalld    //停止系统默认的防火墙
systemctl mask firewalld    //屏蔽服务(让它不能启动)
yum remove -y firewalld     //卸载系统自带的防火墙

安装运维基础工具

yum install -y chkconfig  net-tools ntsysv mlocate lrzsz wget lsof setuptool 

安装yum源

yum install -y epel-release
wget https://dev.MySQL.com/get/mysql80-community-release-el7-2.noarch.rpm
yum localinstall -y mysql80-community-release-el7-2.noarch.rpm

MySQL8.0安装

yum install -y bison-devel libaio-devel perl-Data-Dumper
yum install -y mysql-server
systemctl start mysqld     //启动MySQL
systemctl enable mysqld.service  //开机自启动

由于mysql的yum源是在国外，所以，在国内安装很慢，因此，森哥的做法，是直接下载rpm包回来手工安装 。如下操作：

wget https://dev.mysql.com/get/Downloads/MySQL-8.0/mysql-8.0.19-1.el7.x86_64.rpm-bundle.tar
tar -xvf mysql-8.0.19-1.el7.x86_64.rpm-bundle.tar
yum localinstall -y mysql-community-*     //使用localinstall会自己补足未安装的所需要组件
systemctl start mysqld     //启动MySQL
systemctl enable mysqld.service  //开机自启动

修改初始密码

grep 'temporary password' /var/log/mysqld.log     //mysql5.7版本后，初始密码不再为空，默认随机生成，可通过该命令查询
mysql -u root -p   //进入mysql，输入刚刚查到的密码
alter user 'root'@'localhost' identified with mysql_native_password by '三种或以上的八位字符';        //修改密码，并将密码插件更改为mysql_native_password

初始my.cnf配置的内容为：

cat /etc/my.cnf

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/8.0/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 the leading "# " to disable binary logging
# Binary logging captures changes between backups and is enabled by
# default. It's default setting is log_bin=binlog
# disable_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
#
# Remove leading # to revert to previous value for default_authentication_plugin,
# this will increase compatibility with older clients. For background, see:
# https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_default_authentication_plugin
# default-authentication-plugin=mysql_native_password
​
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
​
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

原则上，上面的这个配置，就可以正常使用了。但有时候为了一些业务场合的应用，就需要考虑对其进行修改，以达到符合实现业务的需求。

mkdir /var/log/mysqld
touch /var/log/mysqld/error.log
chown mysql.mysql /var/log/mysqld -R

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/8.0/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 the leading "# " to disable binary logging
# Binary logging captures changes between backups and is enabled by
# default. It's default setting is log_bin=binlog
# disable_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
#
# Remove leading # to revert to previous value for default_authentication_plugin,
# this will increase compatibility with older clients. For background, see:
# https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_default_authentication_plugin
# default-authentication-plugin=mysql_native_password

# server-id = 1    //单MySQL服务下，可以省略不用

datadir=/var/lib/mysql        //数据文件所在位置
socket=/var/lib/mysql/mysql.sock     //sock文件所在位置
log_error = /var/log/mysqld/error.log       //数据库错误日志文件

# skip_name_resolve = 1         //设置这个，说明只能通过IP连接，不用主机名，一般不建议使用

character-set-server=utf8mb4         //数据库默认字符集，可以支持表情符号等，utf8不支持表情符号。另外utf8mb4是mysql8.0起支持的。
collation-server = utf8mb4_general_ci    //数据库字符集对应一些排序等规则，必须和character-set-server对应
transaction_isolation = READ-COMMITTED     //事务隔离级别，默认为可重复读
init_connect='SET NAMES utf8mb4'           //设置client连接mysql时的字符集,防止乱码
max_connections=500                       //最大连接数
max_connect_errors = 1000                  //最大错误连接数
explicit_defaults_for_timestamp = true       //TIMESTAMP如果没有显示声明NOT NULL，允许NULL值
max_allowed_packet = 1024M                     //SQL数据包发送的大小，如果有BLOB对象建议修改成1G

# interactive_timeout = 1800               //MySQL默认的wait_timeout  值为8个小时, interactive_timeout参数需要同时配置才能生效
# wait_timeout = 1800

tmp_table_size = 134217728                //内部内存临时表的最大值，超过了这个值将写入磁盘，系统IO压力增大
max_heap_table_size = 134217728

# query_cache_size = 0                   //禁用mysql的缓存查询结果集功能，可根据业务需求是否开启，通常为关闭
# query_cache_type = 0

# slow_query_log = 1                                   //慢查询sql日志设置
# slow_query_log_file = /var/log/mysqld/slow.log
# long_query_time = 8                                 //慢查询执行的秒数，必须达到此值可被记录
# log_queries_not_using_indexes = 1                   //检查未使用到索引的sql
# log_throttle_queries_not_using_indexes = 5         //开启后，记录慢sql的频次、每分钟记录的条数
# min_examined_row_limit = 100                         // 检索的行数必须达到此值才可被记为慢查询

# skip-log-bin                                    //关闭binlog功能
binlog_expire_logs_seconds=604800                              //binlog日志文件保存的过期时间，过期后自动删除
innodb_log_file_size=60M
innodb_buffer_pool_size=128M

[client]
default-character-set=utf8mb8
socket=/var/lib/mysql/mysql.sock

[mysqld_safe]
open-files-limit = 8192
log-error=/var/log/mysqld.log
socket=/var/lib/mysql/mysql.sock
pid-file=/var/run/mysqld/mysqld.pid

密码恢复

有时候，会将root密码给忘记了，就需要对MySQL进行密码恢复。

在/etc/my.cnf中，的[mysqld]内，加入如下内容：

skip-grant-table             //改为安全模式，无法密码登陆

重启mysqld

systemctl restart mysqld

进入重置密码

mysql -u root -p             //空密码，直接回车
use mysql;
update user set authentication_string='' where user='root';   //先清空密码

注释掉my.cnf中的skip-grant-table，再重启mysqld。然后就可以免密码进入，再修改密码。

mysql -u root -p   //不用输入密码，直接进入
alter user 'root'@'localhost' identified with mysql_native_password by '三种或以上的八位字符';        //修改密码，并将密码插件更改为mysql_native_password

现在就恢复正常使用了。