有向无环图上k步可达查询优化算法  

Optimized algorithm for k-step reachability queries on directed acyclic graphs

作　　者：杜明[1] 杨安平 周军锋 陈子阳 杨云 DU Ming;YANG Anping;ZHOU Junfeng;CHEN Ziyang;YANG Yun(School of Computer Science and Technology,Donghua University,Shanghai 201620,China;School of Information Management,Shanghai Lixin University of Accounting and Finance,Shanghai 201620,China)

机构地区：[1]东华大学计算机科学与技术学院,上海201620 [2]上海立信会计金融学院信息管理学院,上海201620

出　　处：《计算机应用》2020年第2期426-433,共8页journal of Computer Applications

摘　　要：k步可达查询用于在给定的有向无环图(DAG)中回答两点之间是否存在长度不超过k的路径。针对现有方法的索引规模大、查询处理效率低的问题,提出一种基于部分点的双向最短路径索引来提升索引的可达信息覆盖率,并提出一组优化规则来减小索引规模;然后提出基于简化图的正反互逆拓扑索引来加速回答不可达查询;最后提出远距离优先的双向遍历策略来提高查询处理的效率。基于21个真实数据集(如引用网络、社交网络等)的实验结果表明,相比已有的高效方法PLL及BFSI-B,所提出的算法具有更小的索引规模和更快的查询响应速度。The k-step reachability query is used to answer whether there exists a path between two nodes with length no longer than k in a Directed Acyclic Graph(DAG).Concerning the problems of large index size and low query processing efficiency of existing approaches,a bi-directional shortest path index based on partial nodes was proposed to improve the coverage of reachable queries,and a set of optimization rules was proposed to reduce the index size.Then,a bi-directional reversed topological index was proposed to accelerate the unreachable queries answering based on the simplified graph.Finally,the farthest-node-first-visiting bi-traversal strategy was proposed to improve the efficiency of query processing.Experimental results on 21 real datasets,such as citation networks and social networks,show that compared with existing efficient approaches including PLL(Pruned Landmark Labeling)and BFSI-B(Breadth First Search Index-Bilateral),the proposed algorithm has smaller index size and higher query response speed.

关 键 词：有向无环图 k步可达性查询 hop点最短路径索引 双向互逆拓扑索引 双向遍历 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论]