The VLDB Journal

, Volume 25, Issue 4, pp 495–518

External sorting on flash storage: reducing cell wearing and increasing efficiency by avoiding intermediate writes

Regular Paper

DOI: 10.1007/s00778-016-0426-5

Cite this article as:
Kanza, Y. & Yaari, H. The VLDB Journal (2016) 25: 495. doi:10.1007/s00778-016-0426-5
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Abstract

This paper studies the problem of how to conduct external sorting on flash drives while avoiding intermediate writes to the disk. The focus is on sort in portable electronic devices, where relations are only larger than the main memory by a small factor, and on sort as part of distributed processes where relations are frequently partially sorted. In such cases, sort algorithms that refrain from writing intermediate results to the disk have three advantages over algorithms that perform intermediate writes. First, on devices in which read operations are much faster than writes, such methods are efficient and frequently outperform Merge Sort. Secondly, they reduce flash cell degradation caused by writes. Thirdly, they can be used in cases where there is not enough disk space for the intermediate results. Novel sort algorithms that avoid intermediate writes to the disk are presented. An experimental evaluation, on different flash storage devices, shows that in many cases the new algorithms can extend the lifespan of the devices by avoiding unnecessary writes to the disk, while maintaining efficiency, in comparison with Merge Sort.

Keywords

Sort algorithms External sorting Flash memory Solid-state drive SSD Cell wearing Write endurance Merge Sort 

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Jacobs InstituteCornell TechNew YorkUSA
  2. 2.Computer Science DepartmentHaifa UniversityHaifaIsrael