Two-way Replacement Selection

The performance of external sorting using merge sort is highly dependent on the length of the runs generated. One of the most commonly used run generation strategies is Replacement Selection (RS) because, on average, it generates runs that are twice the size of the memory available. However, the length of the runs generated by RS is downsized for data with certain characteristics, like inputs sorted inversely with respect to the desired output order. The goal of this paper is to propose and analyze two-way replacement selection (2WRS), which is a generalization of RS obtained by implementing two heaps instead of the single heap implemented by RS. The appropriate management of these two heaps allows generating runs larger than the memory available in a stable way, i.e. independent from the characteristics of the datasets. Depending on the changing characteristics of the input dataset, 2WRS assigns a new data record to one or the other heap, and grows or shrinks each heap, accommodating...

• Type: Journal
• Year: 2010
• Where: PVLDB
• Authors: Xavier Martinez-Palau, David Dominguez-Sal, Josep-Lluis Larriba-Pey
• Keywords: PVLDB 2010, Replacement Selection, Sorting, Two-way Replacement Selection