The statistical system tables contain historical data about the usage and the status of the DBMS. The statistical system tables are placed in the system schema EXA_STATISTICS.
The system schemas SYS and EXA_STATISTICS are automatically integrated into the namespace. This means that the tables in the system schemas can be accessed without specifying the schema as long as the same table name is not in use in the current schema.
The tables can also be retrieved in the EXA_SYSCAT system table. Timestamps of historical statistics are stored in the current database time zone (DBTIMEZONE).
Statistics are updated periodically, for an explicit update, you can use the command FLUSH STATISTICS.
Most statistical system tables can be accessed by all users as read-only and are subject to the transactional concept explained in Transaction Management. Therefore, you may have to open a new transaction to see the updated data.
System tables with DBA in its name require the SELECT ANY DICTIONARY privilege to access them.