A Simple and Efficient Parallel Disk Mergesort

External sorting--the process of sorting a file that is too large to fit into the computer's internal memory and must be stored externally on disks--is a fundamental subroutine in database systems [G], [IBM]. Of prime importance are techniques that use multiple disks in parallel in order to speed up the performance of external sorting. The simple randomized merging (SRM) mergesort algorithm proposed by Barve et al. [BGV] is the first parallel disk sorting algorithm that requires a provably optimal number of passes and that is fast in practice. Knuth [K, Section 5.4.9] recently identified SRM (which he calls "randomized striping") as the method of choice for sorting with parallel disks. In this paper we present an efficient implementation of SRM, based upon novel and elegant data structures. We give a new implementation for SRM's lookahead forecasting technique for parallel prefetching and its forecast and flush technique for buffer management. Our techniques amount ...

• Type: Journal
• Year: 2002
• Where: MST
• Authors: Rakesh D. Barve, Jeffrey Scott Vitter
• Keywords: Internal Memory, MST 2002, Parallel Disks, Sorting