Abstract: In a multiprocessor system (FIG. 1), file sorting and merging operations are broken down into a series of partial-file sorts and partial-file merges which are executed in parallel by a plurality of processors (21-26). In a file sorting operation, an input file processor (24) distributes segments (201) of an input file (200) from disk (34) to a plurality of sort processors (21-23) in a round-robin fashion. Each sort processor sorts records (203) of each received segment according to a key, and stores the sorted segments on disk (35) in a temporary file (220). A merge operation is then performed on the sorted segments, treating each segment as an input file. In a merge operation, a plurality of merge processors (21-23) each retrieve a different plurality of sorted segments block (202)-by-block from the temporary file, merge the records of the retrieved segments, and supply records of the merged segments to an output file processor (26).