Derived Class Benefits/Limitations - Teradata Meta Data Services

Derived Class Benefits/Limitations

Derived classes have the following benefits:

Derived classes can be used in the following CMetaObject functions: ReadObject, GetClassObjects, and GetClassObjectsByProperty.

The objects returned will contain all the properties of the base class plus the derived properties.

Searches and sorts can be specified on the derived properties and the base properties of the derived class.

Derived classes have the following limitations:

A derived property can be a maximum of six relationships from the base class.

A derived class is read only.

Derived classes are not supported using the GetCollection functions.

If multiple derived properties are defined for a derived class, their relationships must all be on the same hierarchical path. For example, as shown in Figure 8, a derived class with a base class of Column could contain derived properties from the DBSystem, Database, and Table classes.

Figure 8: Hierarchical Path of Related Classes

An example of what is not permitted is shown in Figure 9.

Figure 9: Related Classes That Cannot Be Used in Same Derived Class

A derived class with a base class of Column cannot contain derived properties from both the View and Table classes.