Reachability computation is a fundamental graph functionality with a wide range of applications. In spite of this, little work has as yet been done on efficient reachability queries over temporal graphs, which are used extensively to model time-varying networks, such as communication networks, social networks, and transportation schedule networks. Moreover, we are faced with increasingly large real-world temporal networks that may be distributed across multiple data centers. This state of affairs motivates the paper’s study of efficient reachability queries on distributed temporal graphs. We propose an efficient index, called Temporal Vertex Labeling (TVL), which is a labeling scheme for distributed temporal graphs. We also present algorithms that exploit TVL to achieve efficient support for distributed reachability querying over temporal graphs in Pregel-like systems. The algorithms exploit several optimizations that hinge upon non-trivial lemmas. Extensive experiments using massive real and synthetic temporal graphs are conducted to provide detailed insight into the efficiency and scalability of the proposed methods, covering both index construction and query processing. Compared with the state-of-the-art methods, the TVL based query algorithms are capable of up to an order of magnitude speedup with lower index construction overhead.

中文翻译：

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大规模时态图的高效分布式可达性查询

可达性计算是具有广泛应用程序的基本图形功能。尽管如此，关于时间图上的有效可达性查询的工作还很少，该图被广泛用于对时变网络进行建模，例如通信网络，社交网络和交通调度网络。此外，我们面临着越来越大的现实世界时态网络，这些网络可能分布在多个数据中心中。这种状态激发了本文对分布式时态图的有效可达性查询的研究。我们提出了一种有效的索引，称为时间顶点标记（TVL），它是用于分布式时间图的标记方案。我们还介绍了利用TVL的算法实现对类似Pregel的系统中的时间图的分布式可达性查询的有效支持。该算法利用了取决于非平凡引理的几种优化。使用大量实时和合成时间图进行了广泛的实验，以提供对所提出方法的效率和可扩展性的详细了解，涵盖索引构建和查询处理。与最新方法相比，基于TVL的查询算法能够以一个较低的索引构建开销达到一个数量级的加速。