Space Management

An operational database should manage space without requiring a restart or down-time for maintenance. When records are deleted, OrientDB has the advantage of automatically reusing the freed space. This is done transparently while the server is online. On the contrary, Neo4j cannot automatically reclaim the space of the deleted records. In fact, to use the freed space, Neo4j requires a complete restart of the server.

Complex domains

Neo4j does not support the creation of schemas against vertex and edges, but only the label concept to group vertices and edges of the same type. Neo4j do not offer ways to support inheritance, polymorphism nor complex constraints. In fact, it only supports the uniqueness of values using indexes.

In contrast, OrientDB supports the creation of schemas around graphs. It is also possible to create subclasses of Vertex and Edges through inheritance and polymorphism.

Concerning the management of relationship, ArangoDB is based on edges and do not support ‘links’. However, OrientDB offers this useful feature. It thus enables to avoid the overhead of edges by allowing unidirectional relationships (like a hyperlink on the web).

With OrientDB, it is possible to decide whether to embed documents or link to them directly. To search a document, OrientDB resolves automatically all the links. This is one key difference with other document database like MongoDB.