Overloading your UDx

You may want your UDx to accept several different signatures (sets of arguments). For example, you might want your UDx to accept:

• One or more optional arguments.

• One or more arguments that can be one of several data types.

• Completely distinct signatures (either all INTEGER or all VARCHAR, for example).

You can create a function with this behavior by creating several factory classes, each of which accepts a different signature (the number and data types of arguments). You can then associate a single SQL function name with all of them. You can use the same SQL function name to refer to multiple factory classes as long as the signature defined by each factory is unique. When a user calls your UDx, Vertica matches the number and types of arguments supplied by the user to the arguments accepted by each of your function's factory classes. If one matches, Vertica uses it to instantiate a function class to process the data.

Multiple factory classes can instantiate the same function class, so you can re-use one function class that is able to process multiple sets of arguments and then create factory classes for each of the function signatures. You can also create multiple function classes if you want.

See the C++ example: overloading your UDx and Java example: overloading your UDx examples.