Schema Validation And Evolution For Graph Databases

Despite the maturity of commercial graph databases, little consensus has been reached so far on the standardization of data definition languages (DDLs) for property graphs (PG). Discussion on the characteristics of PG schemas is ongoing in many standardization and community groups. Although some basic aspects of a schema are already present in most commercial graph databases, full support is missing allowing to constraint property graphs with more or less flexibility.In this paper, we show how schema validation can be enforced through homomorphisms between PG schemas and PG instances by leveraging a concise schema DDL inspired by Cypher syntax. We also briefly discuss PG schema evolution that relies on graph rewriting operations allowing to consider both prescriptive and descriptive schemas.