基于MapReduce的增广动态Skyline查询处理方法

Skyline查询能够计算大规模的数据集中满足多个标准的最优解，被广泛应用于多目标决策等领域.动态skyline查询作为skyline查询的一种重要变体，其结果随着查询点的不同而动态改变，为用户在指定查询要求方面提供了更大的灵活性.然而，随着数据量的不断增加，动态skyline查询会产生大量的查询结果，忽略了查询点的维度方向性和数据的全局整体性，给用户的选择带来极大困难.因此，需要进一步优化动态skyline查询的结果集，提高全局整体性，过滤冗余数据.针对上述问题，提出一种基于MapReduce的增广动态skyline查询处理方法.该方法将原始数据按照维度信息进行分区，在多个节点并行计算动态skyline，优化传统动态skyline结果集，同时提供全局更优的结果供用户选择.在此基础上，针对用户给出某些维度的容忍度的情况，提出一种引入用户容忍度的增广动态skyline查询处理方法.该方法可以根据用户容忍度缩减增广动态skyline查询的原始数据集，很大程度上减少中间结果的比较次数，并且提高了结果集的准确度.大量实验证明，基于MapReduce的增广动态skyline查询处理方法具有更好的有效性、准确性和可用性.

Augmented Dynamic Skyline Query Processing Method Based on MapReduce

Skyline query can compute the optimal solution which meets the multiple standards in large-scale dataset.It has been widely applied for multi-objective decisions.Dynamic skyline query,as an important variant of skyline,its result can be dynamically changed with choosing different query points,providing more flexibility when the users make some specified needs.However,dynamic skyline query can return a large number of query results and ignore the directionality of query point and data integrality,making difficult for users to choose.It is necessary to optimize the result set of dynamic skyline,improving the whole data integrality and filtering a large number of redundant data.Focusing on these problems,we propose the augmented dynamic skyline query method based on MapReduce.The algorithm partitions the original data according to dimensional information,parallel computes dynamic skyline points in multiple nodes,optimizes the result set of the traditional dynamic skyline and at the same time provides the more global optimal results for the user to choose.In addition,when the users provide the tolerance of some dimensions,we propose the augmented dynamic skyline query with user tolerance.The algorithm reduces the original dataset according to the user tolerance and reduces the comparison times of intermediate results with improving the accuracy of the result set.The experiment results show that the augmented dynamic skyline query method based on MapReduce is efficient,accurate and scalable.