The TiDB System Database is similar to MySQL, which contains tables that store information required by the server when it runs.
These system tables contain grant information about user accounts and their privileges:
user: user accounts, global privileges, and other non-privilege columns
db: database-level privileges
tables_priv: table-level privileges
columns_priv: column-level privileges
help_topic is NULL.
stats_buckets: the buckets of statistics
stats_histograms: the histograms of statistics
stats_meta: the meta information of tables, such as the total number of rows and updated rows
gc_delete_range: to record the data to be deleted
GLOBAL_VARIABLES: global system variable table
tidb: to record the version information when TiDB executes