Evaluating Regular Path Queries on Compressed Adjacency Matrices

Regular Path Queries (RPQs), which are essentially regular expressions to be matched against the labels of paths in labeled graphs, are at the core of graph database query languages like SPARQL. A way to solve RPQs is to translate them into a sequence of operations on the adjacency matrices of each label. We design and implement a Boolean algebra on sparse matrix representations and, as an application, use them to handle RPQs. Our baseline representation uses the same space as the previously most compact index for RPQs and excels in handling the hardest types of queries. Our more succinct structure, based on k(2)-trees, is 4 times smaller and still solves complex RPQs in reasonable time.