Pretty much all entity related constructs should work out of the box in Hibernate OGM. @Entity, @Table, @Column, @Enumarated, @Temporal, @Cacheable and the like will work as expected. If you want an example, check out Chapter 2, Getting started with Hibernate OGM or the documentation of Hibernate ORM. Let’s concentrate of the features that differ or are simply not supported by Hibernate OGM.

The various inheritance strategies are not supported by Hibernate OGM, only the table per concrete class strategy is used. This is not so much a limitation but rather an acknowledgment of the dynamic nature of NoSQL schemas. If you feel the need to support other strategies, let us know (see Section 1.2, “How to contribute”). Simply do not use @Inheritance nor @DiscriminatorColumn.

Secondary tables are not supported by Hibernate OGM at the moment. If you have needs for this feature, let us know (see Section 1.2, “How to contribute”).

Queries are partially supported, you will find more information in the query chapter.

All standard JPA id generators are supported: IDENTITY, SEQUENCE, TABLE and AUTO. If you need support for additional generators, let us know (see Section 1.2, “How to contribute”).

@Entity
public class Breed {

    @Id @GeneratedValue(generator = "uuid")
    @GenericGenerator(name="uuid", strategy="uuid2")
    public String getId() { return id; }
    public void setId(String id) { this.id = id; }
    private String id;

    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    private String name;
}

Most Java built-in types as supported at this stage. However, custom types (@Type) are not supported.

Here is a list of supported Java types:

Let us know if you need more type support Section 1.2, “How to contribute”

All association types are supported (@OneToOne, @OneToMany, @ManyToOne, @ManyToMany). Likewise, all collection types are supported (Set, Map, List). The way Hibernate OGM stores association information is however quite different than the traditional RDBMS representation. Each chapter dedicated to a datastore describes how associations are persisted, make sure to check them out.

Keep in mind that collections with many entries won’t perform very well in Hibernate OGM (at least today) as all of the association navigation for a given entity is stored in a single key. If your collection is made of 1 million elements, Hibernate OGM stores 1 million tuples in the association key.