Geeta Chaudhry

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We present the design and implementation of a parallel out-of-core sorting algorithm, which is based on Leighton's columnsort algorithm. We show how to relax some of the steps of the original columnsort algorithm to permit a faster out-of-core implementation. Our algorithm requires only 4 passes over the data, and a 3-pass implementation is possible.(More)
Our goal is to develop a robust out-of-core sorting program for a distributed-memory cluster. The literature contains two dominant paradigms for out-of-core sorting algorithms: merging-based and partitioning-based. We explore a third paradigm, that of oblivious algorithms. Unlike the two dominant paradigms, oblivious algorithms do not depend on the input(More)
Sorting very large datasets is a key subroutine in almost any application that is built on top of a large database. Two ways to sort out-of-core data dominate the literature: merging-based algorithms and partitioning-based algorithms. Within these two paradigms, all the programs that sort out-of-core data on a cluster rely on assumptions about the input(More)
Previous implementations of out-of-core columnsort limit the problem size to <i>N</i> &#8804;(<i>M/P</i>)<sup>3</sup>/2, where <i>N</i> is the number of records to sort, <i>P</i> is the number of processors, and <i>M</i> is the total number of records that the entire system can hold in its memory. We implemented two variations to out-of-core columnsort that(More)
We compare two algorithms for sorting out-of-core data on a distributed-memory cluster. One algorithm, Csort, is a 3-pass oblivious algorithm. The other, Dsort, makes three passes over the data and is based on the paradigm of distribution-based algorithms. In the context of out-of-core sorting, this study is the first comparison between the paradigms of(More)
Leighton’s columnsort algorithm sorts on an r × s mesh, subject to the restrictions that s is a divisor of r and that r ≥ 2s2 (so that the mesh is tall and thin). We show how to mitigate both of these restrictions. One result is that the requirement that s is a divisor of r is unnecessary; columnsort sorts correctly whether or not s divides r . We present(More)
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