PG-Schema: Schemas for Property Graphs

Property graphs have reached a high level of maturity, witnessed by multiple robust graph database systems as well as the ongoing standardization effort aiming at a creating a new standard Graph Query Language (GQL). Yet, despite documented demand, schema support is limited in existing systems. It is anticipated that the second version of the GQL Standard will have an rich DDL. With is in mind, we propose PG-SCHEMAS, a simple yet powerful formalism for specifying property graph schemas, featuring flexible type definitions supporting multi-inheritance as well as an expressive constraint language based on recently proposed PG-KEYS.