Modifying the data model by using Class Manager

The Common Data Model (CDM) is the set of Configuration Item (CI) and relationship classes that ship with BMC Helix CMDB. These CI and relationship classes cover most business scenarios. If the out-of-the-box classes do not cover all that scenarios for your business, you must then extend the data model.  You can extend the CDM by either creating your own classes or extending an existing class with additional attributes.

Related topics

Modifying the CMDB Common Data Model

Common-data-model
Knowledge Article 000095846: Restoring missing common data model attributes from class hierarchy

Retrieving-federated-data-stored-externally-by-creating-federated-classes


Best practice
Whenever you extend the data model, use your own namespace instead of BMC.CORE. This prevents your extensions from being overwritten by new classes when you upgrade to a future version of the CDM.

Never modify the core CDM class attributes because upgrades across versions overwrite these customizations. Modifications to the CDM, such as changing the attribute field length in a class are not preserved during upgrades.

On the other hand, a new class or an extended class with additional attributes is not overwritten during an upgrade. Creating or extending a class may have a significant business impact and you must perform these modifications only after careful planning and consideration of all eventualities.

This section contains information on the following tasks and concepts:

Do not use Developer Studio to edit any CMDB-related forms, as it might cause data model sync issues.



 

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