We use cookies to improve your experience with our site.

大规模相关不确定图上基于阈值的最短路径查询

Threshold-Based Shortest Path Query over Large Correlated Uncertain Graphs

  • 摘要: 随着不确定数据的研究发展,不确定图上的查询处理在研究领域中成为一个热门课题。作为最重要的查询之一,不确定图上最短路径查询因其广泛应用引起了研究人员的兴趣。虽然现有的很多工作能够解决这个查询,但这些工作忽略了一个非常重要的因素,即不确定图中共享结点的边之间是存在相关性的。本文中,我们使用马尔科夫网络来建模不确定图中这种隐含的相关性,并在其上求解最短路径问题。然而,在马尔科夫网络所建模的相关不确定图上计算最短路径及其概率是一个#P-难的问题,于是,我们提出一个过滤-验证框架来加速查询计算。在过滤步骤中,我们设计了一个基于图上的块和点割的概率最短路径索引。我们计算出一系列的最短路径概率上届,并将图中最短路径上届无法过阈值的点和边过滤掉。通过仔细的寻找这些块和点割,我们可以设计出具有最大过滤能力的最优索引。在验证步骤中,我们提出一种有效的采样算法来确定最终结果。最后,我们通过大量的实验证实了我们所提出的算法的高效性和有效性。

     

    Abstract: With the popularity of uncertain data, queries over uncertain graphs have become a hot topic in the database community. As one of the important queries, the shortest path query over an uncertain graph has attracted much attention of researchers due to its wide applications. Although there are some efficient solutions addressing this problem, all existing models ignore an important property existing in uncertain graphs: the correlation among the edges sharing the same vertex. In this paper, we apply Markov network to model the hidden correlation in uncertain graphs and compute the shortest path. Unfortunately, calculating the shortest path and corresponding probability over uncertain graphs modeled by Markov networks is a #P-hard problem. Thus, we propose a filtering-and-verification framework to accelerate the queries. In the filtering phase, we design a probabilistic shortest path index based on vertex cuts and blocks of a graph. We find a series of upper bounds and prune the vertices and edges whose upper bounds of the shortest path probability are lower than the threshold. By carefully picking up the blocks and vertex cuts, the index is optimized to have the maximum pruning capability, so that we can filter a large number of vertices, which make no contribution to the final shortest path query results. In the verification phase, we develop an efficient sampling algorithm to determine the final query answers. Finally, we verify the efficiency and effectiveness of our solutions with extensive experiments.

     

/

返回文章
返回