MySQL 8.0 Reference Manual  /  MySQL Data Dictionary  /  Data Dictionary Schema

Pre-General Availability Draft: 2017-05-26

15.1 Data Dictionary Schema

Data dictionary tables are invisible and cannot be accessed directly. However, MySQL supports access to data stored in data dictionary tables through INFORMATION_SCHEMA tables and SHOW statements. For an overview of the tables that comprise the data dictionary, see Data Dictionary Tables.

MySQL system tables still exist in MySQL 8.0 and can be viewed by issuing a SHOW TABLES statement on the mysql system database. Generally, the difference between MySQL system tables and data dictionary tables is that system tables contain auxiliary data such as time zone and help information, whereas data dictionary tables contain data required to execute SQL queries. MySQL system tables and data dictionary tables also differ in how they are upgraded. Upgrading MySQL system tables requires running mysql_upgrade. Data dictionary upgrades are managed by MySQL Server.

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