1. A database processing method of executing a function which is previously defined and registered in a database, in accordance with a processing request issued from an end user to perform a database processing, said method comprising the steps of: creating index definition information such that a specific user-defined function is set in correspondence to a specific index which is used when carrying out an index access to data of a database region; creating module definition information such that a specific index, which is used when carrying out an index access to the data of the database region, is set in correspondence to an implementation module for subjecting the data of the database region to a specific processing; recognizing that for a processing request for the database issued from an end user, a user-defined function under request is set in correspondence to the specific index by the index definition information, and selecting from the module definition information, a specific implementation module for carrying out an access using the specific index on the basis of the recognition by said recognizing step; and executing the database processing using the selected implementation module.