Modifying online databases

IMS provides several methods for modifying IMS databases without taking them offline, including dynamic resource definition support, which uses type-2 commands, the online change function, which uses the type-1 commands, HALDB and DEDB alter functions, and when the IMS management of ACBs is enabled, DDL or the IMPORT DEFN SOURCE(CATALOG) command.

Each of the methods has different prerequisites and steps, and each of the methods supports different types of database modifications.

For example, the online change function requires a MODBLKS system definition and dynamic resource definition does not. To modify a database by using DDL statements, the IMS management of ACBs must be enabled.You start the HALDB Alter function by issuing the INIT OLREORG command, but you start the DEDB Alter function by running the DEDB Alter utility (DBFUDA00).