Calling a UDR Directly (Server)

From within a C UDR, you can directly call another C function when the following conditions are met:

• At compile time, you know the name of the C function that you want to call.
• The C function resides in the same shared-object file as the calling UDR.

This C function can be a registered UDR. In Figure 49, assume that the func2( ) and func3( ) functions were registered as user-defined functions with the CREATE FUNCTION statement. The func3( ) user-defined function can directly call the func2( ) UDR because func3( ) and func2( ) reside in the same shared-object file, source1.so.

Figure 49. Calling a UDR Directly from Another UDR

If the UDR that you want to call is an overloaded routine, the database server executes the version of the UDR that resides in the same shared-object file. This UDR gets neither parameter casting nor a default MI_FPARAM structure. If no version of this UDR exists in the same shared-object file, you receive a runtime error. To execute UDRs in other shared-object files, use the Fastpath interface.