If you specify a UDF as the MAP routine for an ordering, it must obey the following rules:
- It must have one and only one parameter.
- The data type of the single parameter you specify must be the same as that of the UDT specified as UDT_name.
- The result data type must be a predefined data type.
Its predefined data type is valid except the following:
- It must be declared to be DETERMINISTIC.
- The name you specify for it in the ordering definition must be the name of a UDF contained within the SYSUDTLIB database.
See CREATE FUNCTION and REPLACE FUNCTION (External Form) for details about UDF parameters, result data types, and the DETERMINISTIC option.