Answering Reachability Queries on Incrementally Updated Graphs by Hierarchical Labeling Schema

作     者：Tak-Lam Wong 

作者机构：Department of Mathematics and Information Technology The Hong Kong Institute of Education Hong Kong China 

出 版 物：《Journal of Computer Science & Technology》 (计算机科学技术学报（英文版）)

年 卷 期：2016年第31卷第2期

页      面：381-399页

核心收录：

学科分类：12[管理学] 1201[管理学-管理科学与工程(可授管理学、工学学位)] 080202[工学-机械电子工程] 08[工学] 0804[工学-仪器科学与技术] 0802[工学-机械工程] 

主　　题：graph indexing reachability query Hierarchical Labeling Schema (HLS) incremental update directed cyclic graph 

摘      要：We proposed a novel solution schema called the Hierarchical Labeling Schema （HLS） to answer reachability queries in directed graphs. Different from many existing approaches that focus on static directed acyclic graphs （DAGs）, our schema focuses on directed cyclic graphs （DCGs） where vertices or arcs could be added to a graph incrementally. Unlike many of the traditional approaches, HLS does not require the graph to be acyclic in constructing its index. Therefore, it could, in fact, be applied to both DAGs and DCGs. When vertices or arcs are added to a graph, the HLS is capable of updating the index incrementally instead of re-computing the index from the scratch each time, making it more efficient than many other approaches in the practice. The basic idea of HLS is to create a tree for each vertex in a graph and link the trees together so that whenever two vertices are given, we can immediately know whether there is a path between them by referring to the appropriate trees. We conducted extensive experiments on both real-world datasets and synthesized datasets. We compared the performance of HLS, in terms of index construction time, query processing time and space consumption, with two state-of-the-art methodologies, the path-tree method and the 3-hop method. We also conducted simulations to model the situation when a graph is updated incrementally. The performance comparison of different algorithms against HLS on static graphs has also been studied. Our results show that HLS is highly competitive in the practice and is particularly useful in the cases where the graphs are updated frequently.