MySQL 8.4 Release Notes
本节描述了 MySQL 数据字典引入的临时限制。This section describes temporary limitations introduced with the MySQL data dictionary.
不支持在数据目录下手动创建数据库目录（例如使用 mkdir）。手动创建的数据库目录不会被 MySQL 服务器识别。Manual creation of database directories under the data directory (for example, with mkdir) is unsupported. Manually created database directories are not recognized by the MySQL Server.
因为写入存储、撤销日志和重做日志而不是
.frm文件，DDL 操作需要更长时间。DDL operations take longer due to writing to storage, undo logs, and redo logs instead of.frmfiles.