System catalog in DBMS: Tracking details of database objects

System catalog is a collection of tables in a database which are used by the DBMS for describing the structure of the database. System catalog is created automatically whenever a database is created. System catalogs can also be accessed by the users of the database. A user can access the system catalog to get more info about the structure of a database. However, a user can only read the system catalog and he can’t modify it. Since modifying the system catalog will result in the modification of the structure of the entire database. System catalog can also be used to access query tools where a user can select different tables easily.

System catalog tracks the details of the following database objects:

1) Columns: System catalog maintains all the necessary information related to every column in a database. For Example, name of a column, associated table, size, data type, etc.

2) Tables: A system catalog maintains all the necessary information related to every table in a database. For Example: name of a table, owner, size, number of columns, etc.

3) Views: System catalog maintains all the necessary information related to every view in a database. For Example: name, owner, query which defines the view, etc.

4) Users: System catalog maintains all the necessary information related to every user in a database. For Example: user name, password, etc.

5) Privileges: It maintains all the necessary information related to every set of privileges in a database. For Example: name of grantor, name of grantee, privileges granted, object on which privileges are granted, etc.