背景mysql5.7实例出现误操作删除了performance_schema和sys库
恢复方案使用mysql_upgrade命令操作恢复
直接执行mysql_upgrade -u -p 修复
查看官档mysql_upgrade 命令执行会做检查和修复动作，这个会吧删除的系统库修复
If mysql_upgrade finds that a table has a possible incompatibility, it performs a table check and, if problems are found, attempts a table repair.
https://dev.mysql.com/doc/refman/5.7/en/mysql-upgrade.html
