PG-Schema: Schemas for Property Graphs

Property graphs have reached a high level of maturity, witnessed by multiple robust graph database systems as well the ongoing ISO standardization effort aiming at creating new standard Graph Query Language (GQL). Yet, despite documented demand, schema support is limited both in existing and first version GQL Standard. It anticipated that second Standard will include rich DDL. Aiming to inspire development enhance capabilities systems, we propose PG-Schema, simple yet powerful formalism for specifying property schemas. features PG-Schema with flexible type definitions supporting multi-inheritance, expressive constraints based on recently proposed PG-Keys formalism. We provide formal syntax semantics which meet principled design requirements grounded contemporary management scenarios, offer detailed comparison its those languages systems.