Patent ID: 7206793

Claim:
A computer-implemented method for generating an updated master file, the method comprising: reading a plurality of records of a master file exactly once and reading a plurality of transaction files to generate an updated master file; wherein each record of the plurality of records of the master file is identified by at least one key; wherein each transaction file of the plurality of transaction files comprise at least one record, each record identifiable by at least one key; wherein the records in the master file and each of the transaction files are sorted by its at least one key; and wherein generating the updated master file comprises the steps of: (a) reading a record and its associated key value from the master file and each of the plurality of transaction files; (b) storing a last-read key value for the master file and each of the plurality of transaction files based on said reading in step (a); (c) determining a current key value as an optimum of the last-key values for all of the master file and plurality of transaction files; (d) determining which of the master file and the plurality of transaction files has a last-read key value equal to the current key value; (e) processing the last-read record from each of the master file and the plurality of transaction files whose last-read record from each of the master file and the plurality of transaction files whose last-read key value equals the current key value to generate a record in the updated master file; (f) reading a record and its associated key, or an end-of-file indication, from each of the master file and the plurality of transaction files whose last-read key value equals the current key value; (g) updating the last-read key value for each of the master file and the plurality of transaction files based on said reading in step (f); and (h) repeating steps (c) through (g) at least once.