Functions that provide cast, ordering, or transform functionality for a UDT must satisfy certain requirements.
| IF the UDT is … | AND the function provides … | THEN the C/C++ function must … |
|---|---|---|
| structured | cast functionality from another UDT or predefined type to the UDT | set the attribute values of the UDT result using the value of the input argument. |
| cast functionality from the UDT to another UDT or predefined type | set the value of the result using the attribute values of the UDT input argument. | |
| transform functionality for importing the UDT to the server | transform the value of the predefined type input argument into attribute values of the UDT result. | |
| transform functionality for exporting the UDT from the server | transform the attribute values of the UDT into an appropriate value for the predefined type result. | |
| ordering functionality for comparing two UDTs | use the attribute values of the UDT to set the result to a value that Vantage uses for comparisons. | |
| distinct | cast functionality from another UDT or predefined type to the UDT | set the value of the UDT result using the value of the input argument. |
| cast functionality from the UDT to another UDT or predefined type | set the value of the result using the value of the UDT input argument. | |
| transform functionality for importing the UDT to the server | transform the value of the predefined type input argument into the value of the UDT result. | |
| transform functionality for exporting the UDT from the server | transform the value of the UDT into an appropriate value for the predefined type result. | |
| ordering functionality for comparing two UDTs | use the value of the UDT to set the result to a value that Vantage uses for comparisons. |
Vantage automatically generates cast functionality between a distinct type and its predefined source type. You can create additional functions for casting between a distinct type and other predefined data types or UDTs.
Although Vantage automatically generates transform and ordering functionality when you create a distinct type, you can drop the functionality and provide your own. Note that Vantage does not automatically generate ordering functionality for distinct UDTs where the source data type is a LOB.