1. A data processing method for a database engine to process a request, the method comprising the steps: (a) receiving the request, wherein the request comprises a function that processes at least one data item specified in the request; (b) retrieving the at least one data item from a database; and (c) invoking the function, wherein the invoking step comprises passing to the function at least one parameter, wherein the at least one parameter comprises information related to the at least one data item.