Method and system of externalising / internalising a data record that allow processing of part or all of the record

A method of external data storage in a system including a primary processing device, having a processor and a primary data storage unit, adapted to run application programs for processing active records in the processor and configured to store data belonging to active records in the primary data storage unit; and a secondary data storage system, accessible to the primary processing device, includes loading data belonging to an active record into the primary data storage unit and externalising the record by transferring at least a piece of data belonging to the record to the secondary data storage system for storage. The step of externalising a record includes the making of a call by an application program using data belonging to the record to an interface, arranged to transfer the piece of data to the secondary data storage system.