# PG-Schema: Schemas for Property Graphs

arXiv: https://arxiv.org/abs/2211.10962 · HTML: https://mlsanity.com/paper/2211.10962/

## Key facts

- Cited by 13 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 20 Nov 2022.

## Built on by (most cited first, 13 of 13)

- [Construction of Knowledge Graphs: State and Challenges](https://mlsanity.com/paper/2302.11509/) (2023)
- [Knowledge Graphs in Practice: Characterizing their Users, Challenges, and Visualization Opportunities](https://mlsanity.com/paper/2304.01311/) (2023)
- [Common Foundations for SHACL, ShEx, and PG-Schema](https://mlsanity.com/paper/2502.01295/) (2025)
- [Schema Generation for Large Knowledge Graphs Using Large Language Models](https://mlsanity.com/paper/2506.04512/) (2025)
- [KGpipe: Generation and Evaluation of Pipelines for Data Integration into Knowledge Graphs](https://mlsanity.com/paper/2511.18364/) (2025)
- [IRSKG: Unified Intrusion Response System Knowledge Graph Ontology for Cyber Defense](https://mlsanity.com/paper/2411.15672/) (2024)
- [Evaluation of Pipelines for Data Integration into Knowledge Graphs](https://mlsanity.com/paper/2605.22304/) (2026)
- [Shape Expressions with Inheritance](https://mlsanity.com/paper/2503.24299/) (2025)
- [The KG-ER Conceptual Schema Language](https://mlsanity.com/paper/2508.02548/) (2025)
- [The Equivalence Theorem: First-Class Relationships for Structurally Complete Database Systems](https://mlsanity.com/paper/2603.13603/) (2026)
- [ERUnderstand: Evaluating Vision-Language Models on Structured ER Diagrams](https://mlsanity.com/paper/2607.24707/) (2026)
- [SchemaLink: An Intelligent Web Editor for LinkML Schema Curation](https://mlsanity.com/paper/2608.12529/) (2026)
- [From SQL to Knowledge Graphs: An LLM-Driven Multi-Agent Approach with Data Schema Improvement](https://mlsanity.com/paper/2608.26117/) (2026)

## Abstract (arXiv)

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