改进对全局读锁的要求

[kevinbin]

Is your feature request related to a problem?

云上RDS有可能缺少必要的权限，无法执行全局锁。 全量迁移阶段无法进行alter table 是否因为全局锁或lock table ? 是否可优化？

Describe the solution you'd like

mysql shell 8.0.22 使用lock tables read 替代全局读锁Consistent Dumping without FLUSH TABLES WITH READ LOCK

login mysql with mysqlsh \sql revoke reload on . from root@'localhost' \js util.dumpInstance("/Users/hongbin/workbench/dump") general.log 从日志来看，select out 数据时并没有lock tables，是在select out数据前进行的。 参考https://mysqlserverteam.com/whats-new-in-mysql-shell-8-0-22/

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.