mysql官網不支援誇大版本升級，比如跳過5.6直接升級到5.7，但由於一些客觀原因，專案需要從5.5直接升級到5.7，以下是具體操作

1、備份之前mysql，（資料量少，可直接拷貝安裝目錄及data目錄和配置檔案，本例使用的為Percona XtraBackup工具進行的備份）

2、將data目錄移出mysql5.5安裝目錄

3、解壓mysql5.7版本

4、修改5.7需要配置檔案my.cnf，新增datadir，指向5.5資料目錄

5、初始化，該步驟可選，（新安裝資料庫，或者資料目錄不存在，可執行如下命令初始化資料目錄，本例中不需要執行如下操作）

bin/mysqld --initialize --user=mysql

6、執行ssl相關操作

bin/mysql_ssl_rsa_setup

7、啟動mysql

8、此時資料目錄還是5.5的，需要執行mysql_upgrade進行升級，使用方法與mysql命令登入命令列一樣,mysql會自動檢測當前表並自動修復

mysql_upgrade -uroot -p

9、修復完成後，若發現mysql啟動有server-key.pem相關的ssl錯誤，則是server-key.pem檔案許可權問題

chmod 644 server-key.pem

10、但此時若執行mysqlpum備份資料，可能會出現異常

mysqlpump --user=root --password mytest > mytest.sql

錯誤資訊：

mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not 
 
continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.
mysqlpump: [ERROR] (1577) Cannot proceed because system tables used by Event Scheduler were found damaged at server start
Dump process encountered error and will not continue.

解決方法：重啟mysql服務 （本例中是這樣解決的問題）

重新執行mysqlpump

Dump progress: 1/28 tables, 0/353 rows
Dump progress: 36/343 tables, 0/19746 rows
Dump progress: 180/343 tables, 6151/19746 rows
Dump completed in 3675 milliseconds

資料被正確備份下來，且備份速度很快，從備份檔案可以看到，內容與mysqldump備份有很多不同

本次只是簡單嘗試mysqlpump，待後續再對mysqlpump做深入瞭解