# Where are Tidb System Tables

+ mysql stores TiDB system tables
  + mysql.user, etc.
+ INFORMATION_SCHEMA provides an ANSI standard method view system metadata
  + Tables compatible with MySQL such as TABLES, PROCESSLIST, COLUMNS, etc.
  + Custom tables such as: CLUSTER_CONFIG, CLUSTER_Hardware, TIFLASH_REPLICA, etc.
+ METRICS_SCHEMA is a set of views based on TiDB monitoring metrics in Prometheus
+ PERFORMANCE_SCHEMA currently reserves some views for MySQL compatibility (most internal use)
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- System tables related to TiDB are mainly stored in the following databases
  - mysql
  - INFORMATION_SCHema
  - METRICS_SCHEMA
  - Performance_SCHEMA
- Many of the names are consistent with the mysql database due to compatibility

- TiDB system tables are stored in the mysql library. ranging
  - Tables such as mysql.user can be edited directly.
- INFORMATION_SCHEMA provides an ANSI standard method view system metadata.
  - Includes tables compatible with MySQL such as: TABLES, PROCESSLIST, COLUMNS, etc.
  - Many custom tables are also provided, such as: CLUSTER_CONFIG, CLUSTER_Hardware, TIFLASH_REPLICA, etc.
- METRICS_SCHEMA is a set of views based on TiDB monitoring metrics in Prometheus.
- PERFORMANCE_SCHEMA currently reserves some views for MySQL compatibility. Most views are for internal use and are not introduced