External Sorting for Databases in Distributed Heterogeneous Systems
نویسنده
چکیده
A common approach to external parallel sorting in parallel database query processing is to split the data of initial runs into partitions. These partitions are assigned statically to the processes of the merge phase to produce a globally sorted result. This strategy may lead to low performance if some processes are overloaded caused by data skew or load imbalances. In this paper we describe a new, load{balanced external parallel sorting method which is more robust to data skew and to variable speed of processes. The main ideas are a competitive computation of partitioning values and an adaptive, demand{driven assignment of data to the processes. We compare the run time of our new method with an analogous conventional method in case of data skew and load imbalances.
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