Reachability queries checking the existence of a path from a source node to a target node are fundamental operators for querying and processing graph data. Current approaches for index-based evaluation of reachability queries either focus on plain reachability or constraint-based reachability with alternation only. In this paper, for the first time we study the problem of index-based processing for recursive label-concatenated reachability queries, referred to as RLC queries. These queries check the existence of a path that can satisfy the constraint defined by a concatenation of at most k edge labels under the Kleene plus. Many practical graph database and network analysis applications exhibit RLC queries. However, their evaluation remains prohibitive in current graph database engines. We introduce the RLC index, the first reachability index to efficiently process RLC queries. The RLC index checks whether the source vertex can reach an intermediate vertex that can also reach the target vertex under a recursive label-concatenated constraint. We propose an indexing algorithm to build the RLC index, which guarantees the soundness and the completeness of query execution and avoids recording redundant index entries. Comprehensive experiments on real-world graphs show that the RLC index can significantly reduce both the offline processing cost and the memory overhead of transitive closure while improving query processing up to six orders of magnitude over online traversals. Finally, our open-source implementation of the RLC index significantly outperforms current mainstream graph engines for evaluating RLC queries.
翻译:从源节点到目标节点的可查询性查询是查询和处理图表数据的基本操作器。目前基于索引的可查询评估方法要么侧重于简单可达性,要么仅以交替方式进行限制可达性。在本文件中,我们首次研究基于索引的处理问题,以进行循环标签保密可达性查询,称为RLC查询。这些查询检查是否存在一种路径,可以满足在Kleene+下最多K边缘标签的合并所定义的限制。许多实用的图表数据库和网络分析应用程序显示 RLC 查询。然而,在目前的图形数据库引擎中,其评价仍然令人望而不可及。我们引入了RLC 索引,这是高效处理 RLC 查询的第一个可达性索引。RLC 索引首次研究基于索引的处理问题,以循环标签可调解的可达目标的顶点,称为RLC 查询。这些查询方法检查是否存在一种路径,可以满足在可反复贴标签的开放式限制下对目标的顶点。我们提议一种用于构建 RLC 索引的索引的索引,这将保证对当前图表的正确性和完整性进行查询,并且避免在目前对 RLC IM IM 格式的升级 的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级,同时在大幅度上进行大幅的升级的升级的升级的升级的升级最后的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级,同时,在大量的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级