The data dictionary schema stores dictionary data in transactional (InnoDB) tables. 数据字典模式将字典数据存储在事务（InnoDB）表中。Data dictionary tables are located in the mysql database together with non-data dictionary system tables.数据字典表与非数据字典系统表一起位于mysql数据库中。

Data dictionary tables are created in a single InnoDB tablespace named mysql.ibd, which resides in the MySQL data directory. 数据字典表是在一个名为mysql.ibd的InnoDB表空间中创建的，该表空间位于MySQL数据目录中。The mysql.ibd tablespace file must reside in the MySQL data directory and its name cannot be modified or used by another tablespace.mysql.ibd表空间文件必须位于mysql数据目录中，并且其名称不能被其他表空间修改或使用。

Dictionary data is protected by the same commit, rollback, and crash-recovery capabilities that protect user data that is stored in InnoDB tables.字典数据由相同的提交、回滚和崩溃恢复功能保护，这些功能保护存储在InnoDB表中的用户数据。