一、升级前准备

1.1.MySQL提供mysql-shell验证方式，可以下载后进行验证：

下载shell验证文件：
        https://cdn.mysql.com/archives/mysql-shell/mysql-shell-8.0.27-linux-glibc2.12-x86-64bit.tar.gz

         验证是否可以升级成功（验证的时候出现了几个错误没去处理，升级后倒时也没发现问题，如果是生产环境下还是要小心一些）

# 验证mysql升级[root@localhost] tar -xf mysql-shell-8.0.27-linux-glibc2.12-x86-64bit.tar.gz[root@localhost] cd mysql-shell-8.0.27-linux-glibc2.12-x86-64bit/bin[root@localhost] ./mysqlsh -uroot -p'123456' -S /tmp/mysql.sock -e "util.checkForServerUpgrade()"

   1.2. 备份原数据库（防止升级过程中出现问题，导致数据丢失，有条件建议异地备份）    

[root@localhost] mysqldump -uroot -p'123456' --all-databases  --lock-tables=0 > all.sql.bak.20220412[root@localhost] mv all.sql.bak.20220412 /data/backup/mysql/

1.3.下载MySQL8.0

​拉取软件包[root@localhost] wget https://downloads.mysql.com/archives/get/p/23/file/mysql-8.0.21-1.el7.x86_64.rpm-bundle.tar# 解压mysql8.0[root@localhost] tar zxvf mysql-8.0.21-el7-x86_64.tar.gz -C ../server/mysql3306/# 移动到指定目录[root@localhost] mv mysql-8.0.21-el7-x86_64 /usr/local/mysql8# 更改文件夹所属[root@localhost] chown -R mysql.mysql /usr/local/mysql8/

二、升级过程配置

2.1. 修改mysql配置文件，主要是mysql8.0部分，及sql_mode中的NO_ENGINE_SUBSTITUTION

# 编辑配置文件[root@localhost] vim /etc/my.cnf[client]port=3306socket=/tmp/mysql.sock[mysqld]log-bin=mysql-binserver-id=170character_set_server=utf8init_connect='SET NAMES utf8'#basedir=/usr/local/mysql#datadir=/usr/local/mysql/datasocket=/tmp/mysql.socklog-error=/var/log/mysqld.logpid-file=/run/mysqld/mysqld.pid#不区分大小写lower_case_table_names =1sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTIONmax_connections=5000default-time_zone = '+8:00'max_allowed_packet = 32M#default_password_lifetime=90#wait_timeout=600# mysql8.0 addcollation-server=utf8_general_cibasedir=/usr/local/mysql8datadir=/usr/local/mysql/dataskip_ssldefault_authentication_plugin=mysql_native_password

2.2 开始升级

# 进入原mysql命令行[root@localhost] mysql -uroot -p'123456'# 查看mysql版本mysql> select version();+------------+| version()  |+------------+| 5.7.26-log |+------------+1 row in set (0.00 sec)mysql> show variables like 'innodb_fast_shutdown';+----------------------+-------+| Variable_name        | Value |+----------------------+-------+| innodb_fast_shutdown | 1     |+----------------------+-------+1 row in set (0.00 sec)# 确保数据都刷到硬盘上，更改成0mysql> set global innodb_fast_shutdown=0;Query OK, 0 rows affected (0.00 sec)mysql> shutdown;Query OK, 0 rows affected (0.00 sec)mysql> exit;Bye

2.3 使用安全模式启动mysql8.0，正常启动后可以进入到mysql命令行，如果没启动成功，需要查看日志cat /var/log/mysqld.log解决后，再进入命令行

# 使用mysql8.0启动[root@localhost] /usr/local/mysql8/bin/mysqld_safe --defaults-file=/etc/my.cnf --user=mysql &# 进入mysql命令行[root@localhost] mysql -uroot -p'123456'mysql> select version();+-----------+| version() |+-----------+| 8.0.27    |+-----------+1 row in set (0.00 sec)mysql> exit;Bye

2.4 配置环境变量

[root@localhost] vim /etc/profile# add mysqlexport PATH=$PATH:/usr/local/mysql8/bin# 使环境变量生效[root@localhost] source /etc/profile

2.5查看客户端版本配置

# 验证版本[root@localhost] which mysql/usr/local/mysql8/bin/mysql# 查看版本[root@localhost] mysql -Vmysql  Ver 8.0.27 for Linux on x86_64 (MySQL Community Server - GPL)

三、配置启动项

[root@localhost] cp /usr/local/mysql8/support-files/mysql.server /etc/init.d/mysqld# 修改启动项目[root@localhost] vim /etc/init.d/mysqld# 修改目录位置basedir=/usr/local/mysql8datadir=/usr/local/mysql/data# 添加到启动列表 [root@localhost] chkconfig --add mysqld# 刷新启动信息[root@localhost] systemctl daemon-reload# 查看启动项列表[root@localhost] chkconfig --list

重新启动服务器没有成功，启动的时候报错没有mysqld.pid文件，创建后启动成功

# 重启动无法创建mysqld.pid文件处理方法[root@localhost] cat /var/log/mysqld.log[root@localhost] cd /run[root@localhost] mkdir mysqld[root@localhost] chown -R mysql.mysql ./mysqld[root@localhost] cd mysqld[root@localhost] touch mysqld.pid[root@localhost] chown -R mysql.mysql ./mysqld.pid[root@localhost] service mysqld startStarting MySQL.. SUCCESS! 

来源地址：https://blog.csdn.net/ArrogantB/article/details/126995829