5.6降级5.5问题

[root@db1 home]# rpm -ivh MySQL-server-5.5.54-1.el6.x86_64.rpmPreparing...                ########################################### [100%]Some previous upgrade was not finished:-rw-r--r-- 1 root root 176 Oct 24 17:20 /var/lib/mysql/RPM_UPGRADE_MARKERPlease check its status, then do    rm /var/lib/mysql/RPM_UPGRADE_MARKERbefore repeating the MySQL upgrade.error: %pre(MySQL-server-5.5.54-1.el6.x86_64) scriptlet failed, exit status 1error:   install: %pre scriptlet failed (2), skipping MySQL-server-5.5.54-1.el6

这是说升级文件有以前的任务没有完成，说明这个版本时以前已经升级了或降级了，现在可以删除，然后再升级或降级

[root@db1 home]# rm /var/lib/mysql/RPM_UPGRADE_MARKERrm: remove regular file `/var/lib/mysql/RPM_UPGRADE_MARKER'? yes

1、无法开启复制

relay-log.info信息与低版本不一致，导致读取信息错误，需要对照低版本vim修改

2、系统表错误

171025 13:45:47 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './performance_schema/events_statements_summary_by_digest.frm'171025 13:45:47 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './performance_schema/host_cache.fr

删除ib_logfile0,重新启动，然后运行mysql_upgrade命令修复

如果不能修复，需要导出主库数据，删除从库表，导入进去，

performance_schema，不能导入，mysql库可以