Derived Class Benefits/Limitations - Teradata Meta Data Services

Teradata Meta Data Services Programmer Guide

Teradata Meta Data Services
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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.