Every database contains a set of system tables, which are special tables used by the system to manage data and the system. These tables are also sometimes called the data dictionary or the system catalog. In IQ they are stored in the Catalog Store.
System tables contain information about the database. You never alter the system tables directly in the way you can alter other tables. The system tables hold information about the tables in a database, the users of a database, the columns in each table, and so on. This information is data about data, or metadata. You can use the system tables to check the size and data type for various columns, prior to inserting data.
