Querying Property Graphs with XPath

Marko Junkkari, Sami-Santeri Svensk, Jyrki Nummenmaa

Abstract: XPath has been established as the de facto standard for searching data items from hierarchical XML structures. Due to its popularity and compact path expressions, XPath has also been recognized as a query language candidate for graph databases where the structure does not follow a hierarchical order. Graph databases are based on graph theory and the data are organized accordingly. Among different types of graphs, property graphs have gained special interest because they allow data associated with edges as well as vertices, reflecting that edges represent relationships and relationships are generally allowed to have properties, just like entities. Earlier proposals to apply XPath to graph databases do not allow manipulation of the properties of edges in a property graph. The present study focuses on this issue. We show how XPath can be applied to full-scale property graphs. This requires a novel mapping of XPath primitives to the primitives of property graphs. Based on this mapping, we define graph-based semantics for XPath by regular path queries, an established logical approach for querying vertices and edges.

External IDs:doi:10.1007/978-3-032-05727-3_7