Parallel external selection algorithm on distributed memory systems

The external selection problem is to select the record with the K-th smallest key from the given N records that are distributed and stored evenly on the D disks for the parallel machine with D processors. Each processor has its own primary memory of size M records and one disk, where N/D>M. The processors are connected with a /spl radic/D /spl times/ /spl radic/D mesh architecture. Based on a two-stage approach, this paper presents an efficient parallel external selection algorithm for the distributed-memory parallel systems. First, all the processors execute local external sorting in parallel, each processor sorts the N/D records on its own disk. Next, they execute parallel external selection from the D sorted sub-files on the D disks. This algorithm is asymptotically optimal and has a small constant factor of time complexity.