Disclaimer: I'm one of the Hibernate OGM developers so I'll try to provide some of the reasons behind it.
Hibernate OGM provides Java Persistence (JPA) support for NoSQL solutions. It reuses Hibernate ORM’s engine but persists entities into a NoSQL datastore instead of a relational database. It also aims to provide access to specific datastore features when JPA does not have a good fit.
This approach is interesting for several reasons:
Known semantic and APIs. Java developers are already familiar with JPA, this means that one won't have to learn lower level API. It also supports both HQL and native backend-queries.
Late backend choice. Choosing the right NoSQL datastore is not trivial. With Hibernate OGM you won't have to commit to a specific NoSQL solution and you will be able to switch and tests different backends easily.
Existing tools and libraries. JPA and Hibernate ORM have been around for a while and you will be able to reuse libraries and tools that uses them underneath.
Most of JPA logical model fits. An example of a good fit is @Embedded
, @EmbeddedCollection
and @Entity
(that can be a node, document or cache based on the datastore of choice). Admittedly, annotation names might be strange because you will also have to deal with @Table
and @Column
.
JPA abstracts persistence at the object level, leaving room for a lot of tricks and optimizations. We have several ideas planned, like polyglot persistence: storing data in several data stores and use the best one for a specific read job.
The main drawback is that some of the concepts of JPA are not easily mapped to the NoSQL world: transactions for example. While you will have access to transaction demarcation methods, you won't be able to rollback on data stores that don't support transactions natively (transactions, in this case, will be used to group operations and try to optimize the number of calls to the db).
Also, if your dataset is by nature non domain model centric, then Hibernate OGM is not for you.