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Multiway Merging in Parallel
January 1996 (vol. 7 no. 1)
pp. 11-17

Abstract—The problem of merging k (k≥ 2) sorted lists is considered. We give an optimal parallel algorithm which takes $O({\textstyle{{n\log k} \over p}}+\log n)$ time using p processors on a parallel random access machine that allows concurrent reads and exclusive writes, where n is the total size of the input lists. This algorithm achieves O(log n) time using $p={\textstyle{{n\log k} \over {\log n}}}$ processors. Most of the previous research for this problem has been focused on the case when k = 2. Very recently, parallel solutions for the case when k > 2 have been reported. Our solution is the first logarithmic time optimal parallel algorithm for the problem when k≥ 2. It can also be seen as a unified optimal parallel algorithm for sorting and merging. In order to support the algorithm, a new processor assignment strategy is also presented.

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Index Terms:
Analysis of algorithms, databases, information retrieval, merging, parallel computation, processors assignment, sorting.
Zhaofang Wen, "Multiway Merging in Parallel," IEEE Transactions on Parallel and Distributed Systems, vol. 7, no. 1, pp. 11-17, Jan. 1996, doi:10.1109/71.481593
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