PG-FD: Mapping Functional Dependencies to the Future Property Graph Schema Standard

There has been a notable effort, in the past five years, to develop and promote Graph Query Language, GQL, as a standard for querying graph data, akin to the role SQL plays in relational data querying. Although this goal is still a work in progress, the graph database community has been advancing by not only defining the GQL specification but also introducing additional specifications such as Property Graph Key, PG-Key, and later Property Graph Schema, PG-Schema, for specifying graph schema and dependencies. In this regard, a number of proposals have been made in the literature for expressing Functional Dependencies in graph data. Our first contribution is a survey of such proposals, highlighting important ones and their differences. Our second contribution is a solution for translating dependencies defined within such proposals into dependencies that conform to PG-Schema. Our solution is accompanied by a working prototype for translating graph dependencies into PG-Schema compliant dependencies.