Linux6 將 mysql5.1 升級到 mysql8.0（yum源）
由於我的mysql是5.1版本的，導入SQL時，字符編碼是utf8mb4的，mysql得版本5.5以上才支持，故低版本的報錯。
utf8與utf8mb4（utf8 most bytes 4）
- MySQL 5.5.3之后增加了utfmb4字符編碼
- 支持BMP（Basic Multilingual Plane，基本多文種平面）和補充字符
- 最多使用四個字節存儲字符
utf8mb4是utf8的超集並完全兼容utf8，能夠用四個字節存儲更多的字符。
標准的UTF-8字符集編碼是可以使用1-4個字節去編碼21位字符，這幾乎包含了世界上所有能看見的語言。
MySQL里面實現的utf8最長使用3個字符，包含了大多數字符但並不是所有。例如emoji和一些不常用的漢字，如“墅”，這些需要四個字節才能編碼的就不支持。
將mysql 5.1 升級到 8.0
官網下載對應系統的yum源
將rpm包上傳到服務器，然后安裝
# yum install mysql80-community-release-el6-3.noarch.rpm Loaded plugins: fastestmirror Setting up Install Process ... Installed: mysql80-community-release.noarch 0:el6-3 Complete!
8.0版本的yum源配置后，進行升級操作，升級前確認已經備份好數據庫及對應的配置文件。關掉mysql服務。
[root@centos6 download]# service mysqld stop
Stopping mysqld: [ OK ]
[root@centos6 download]#
不需要卸載原來的mysql，使用“yum update”升級即可
[root@centos6 download]# yum update mysql-server Loaded plugins: fastestmirror Setting up Update Process Loading mirror speeds from cached hostfile ... ===================================================================================== Package Arch Version Repository Size ===================================================================================== Installing: mysql-community-client x86_64 8.0.19-1.el6 mysql80-community 47 M replacing mysql.x86_64 5.1.73-8.el6_8 mysql-community-devel x86_64 8.0.19-1.el6 mysql80-community 7.8 M replacing mysql-devel.x86_64 5.1.73-8.el6_8 mysql-community-libs x86_64 8.0.19-1.el6 mysql80-community 4.6 M replacing mysql-libs.x86_64 5.1.73-8.el6_8 mysql-community-libs-compat x86_64 8.0.19-1.el6 mysql80-community 1.7 M replacing mysql-libs.x86_64 5.1.73-8.el6_8 mysql-community-server x86_64 8.0.19-1.el6 mysql80-community 520 M replacing mysql-server.x86_64 5.1.73-8.el6_8 Installing for dependencies: mysql-community-common x86_64 8.0.19-1.el6 mysql80-community 727 k numactl x86_64 2.0.9-2.el6 base 74 k Transaction Summary ===================================================================================== Install 7 Package(s) Total download size: 582 M ... Replaced: mysql.x86_64 0:5.1.73-8.el6_8 mysql-devel.x86_64 0:5.1.73-8.el6_8 mysql-libs.x86_64 0:5.1.73-8.el6_8 mysql-server.x86_64 0:5.1.73-8.el6_8 Complete!
升級后啟動，會發現啟動失敗。
[root@centos6 download]# service mysqld start
MySQL Daemon failed to start.
Starting mysqld: [FAILED]
查看日志
[root@centos6 ~]# tail /var/log/mysqld.log 2020-03-04T08:13:26.769860Z 0 [ERROR] [MY-010119] [Server] Aborting 2020-03-04T08:13:26.770601Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.19) MySQL Community Server - GPL. 2020-03-04T08:17:11.990871Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.19) starting as process 8227 2020-03-04T08:17:12.009990Z 1 [System] [MY-011012] [Server] Starting upgrade of data directory. 2020-03-04T08:17:12.075334Z 1 [ERROR] [MY-012263] [InnoDB] The Auto-extending innodb_system data file './ibdata1' is of a different size 640 pages (rounded down to MB) than specified in the .cnf file: initial 768 pages, max 0 (relevant if non-zero) pages! 2020-03-04T08:17:12.075438Z 1 [ERROR] [MY-012930] [InnoDB] Plugin initialization aborted with error Generic error. 2020-03-04T08:17:12.573744Z 1 [ERROR] [MY-011013] [Server] Failed to initialize DD Storage Engine. 2020-03-04T08:17:12.573957Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed. 2020-03-04T08:17:12.574061Z 0 [ERROR] [MY-010119] [Server] Aborting 2020-03-04T08:17:12.574769Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.19) MySQL Community Server - GPL.
解決方法
# cd /var/lib/mysql
#rm -rf /var/lib/mysql/ib*
主要刪除：ibdata1、ib_logfile0、ib_logfile1文件
之前有安裝mysql-server5.1刪除文件重構后，異常解決。
重啟驗證
[root@centos6 mysql]# /etc/init.d/mysqld restart
Stopping mysqld: [ OK ]
Initializing MySQL database: [ OK ]
Starting mysqld: [ OK ]
查看mysql版本
[root@centos6 mysql]# mysql -V mysql Ver 8.0.19 for Linux on x86_64 (MySQL Community Server - GPL)
說明已經升級成功，重新導入之前備份的數據庫文件，即可使用。