• time_zone : Time zone IDs and whether they use leap seconds. 

• time_zone_leap_second : When leap seconds occur. 

• time_zone_name : Mappings between time zone IDs and names. 

• time_zone_transition , time_zone_transition_type : Time zone descriptions. 

For more information, see Section 5.1.15, “MySQL Server Time Zone Support” . 

## Replication System Tables 

The server uses these system tables to support replication: 

• gtid_executed : Table for storing GTID values. See mysql.gtid_executed Table. 

• ndb_binlog_index : Binary log information for NDB Cluster replication. This table is created only if the server is built with NDBCLUSTER  support. See Section 23.6.4, “NDB Cluster Replication Schema and Tables” . 

• slave_master_info , slave_relay_log_info , slave_worker_info : Used to store replication information on replica servers. See Section 17.2.4, “Relay Log and Replication Metadata Repositories” . 

## Optimizer System Tables 

All of the tables just listed use the InnoDB  storage engine. 

These system tables are for use by the optimizer: 

• innodb_index_stats , innodb_table_stats : Used for InnoDB  persistent optimizer statistics. See Section 15.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” . 

• server_cost , engine_cost : The optimizer cost model uses tables that contain cost estimate information about operations that occur during query execution. server_cost  contains optimizer cost estimates for general server operations. engine_cost  contains estimates for operations specific to particular storage engines. See Section 8.9.5, “The Optimizer Cost Model” . 

## Miscellaneous System Tables 

Other system tables do not fit the preceding categories: 

• audit_log_filter , audit_log_user : If MySQL Enterprise Audit is installed, these tables provide persistent storage of audit log filter definitions and user accounts. See Audit Log Tables. 

• firewall_group_allowlist , firewall_groups , firewall_memebership , firewall_users , firewall_whitelist : If MySQL Enterprise Firewall is installed, these tables provide persistent storage for information used by the firewall. See Section 6.4.7, “MySQL Enterprise Firewall” . 

• servers : Used by the FEDERATED  storage engine. See Section 16.8.2.2, “Creating a FEDERATED Table Using CREATE SERVER” . 

• innodb_dynamic_metadata : Used by the InnoDB  storage engine to store fast-changing table metadata such as auto-increment counter values and index tree corruption flags. Replaces the data dictionary buffer table that resided in the InnoDB  system tablespace. 

## 5.4 MySQL Server Logs 

