System tables

There are multiple types of system tables:

• mysql schema: There are mostly real tables stored on TiKV

• information_schema: These tables are generated on request and not stored on disk.

• performance_schema: These tables are generated on request and not stored on disk.

• metrics_schema: These are metrics from Prometheus, not real tables.

• SYS: these are views etc to make performance_schema easier to use.

See also the docs:

• TiDB mysql schema

• TiDB information_schema

• TiDB performance_schema

• TiDB sys schema

• TiDB metrics_schema

• MySQL performance_schema

• MySQL information_schema

• MySQL sys schema

• MySQL mysql schema