Systems and methods store data in records, each record comprising a plurality of fields. The systems and methods receive an update file that contains a stored field specifying structure that specifies a field that is to be updated in a particular record and that contains the updated data for the field that is to be updated. The systems and methods then write, for the particular record, the updated data that has been extracted from the update file into the field that has been specified by the stored field specifying structure of the update file.