Is MongoDB object-oriented?

Question

In the website of MongoDB they wrote that MonogDB is Document-oriented Database, so if the MongoDB is not an Object Oriented database, so what is it? and what are the differences between Document and Object oriented databases?

Answer 1

This may be a bit late in reply, but just thought it is worth pointing out, there are big differences between ODB and MongoDB.

In general, the focus of ODB is tranparent references (relations) between objects in an arbitarily complex domain model without having to use and manage code for something like a DBRef. Even if you have a couple thousand classes, you don't need to worry about managing any keys, they come for free and when you create instances of those 1000's of classes at runtime, they will automatically create the schema in the database .. even for things like a self-referencing object with collections of collections.

Also, your transactions can span these references, so you do not have to use a completely embedded model.

The concepts are those leveraged in ORM solutions like JPA, the managed persistent object life-cycle, is taken from the ODB space, but the HUGE difference is that there is no mapping AT ALL in the ODB and relations are stored as part of the database so there is no runtime JOIN to resolve relations, all relations are resolved with the same speed as a b-tree look-up. For those of you who have used Hibernate, imagine Hibernate without ANY mapping file and orders of magnitude faster becase there is no runtime JOIN behind the scenes.

Also, ODB allows queries across any relationship in your model, so you are not restricted to queries in a particular collection as you are in MongoDB. Of course, hash/b-tree/aggregate indexes are supported to so queries are very fast when they are used.

You can evolve instances of any class in an ODB at the class level and at runtime the correct class version is resolved. Quite different than the way it works in MongoDB maintaining code to decide how to deal with varied forms of blob ( or value object ) that result from evolving a schema-less database ... or writing the code to visit and change every value object because you wanted to change the schema.

As far as partioning goes, I think it is a lot easier to decide on a partitioning model for a domain model which can talk across arbitary objects, then it is to figure out the be-all, end-all embedding strategy for your collection contained documents in MongoDB. As a rediculous example, you have a Contact and an Address and a ShoppingCart and these are related in a JSON document and you decide to partition on Contact by Contact_id. There is absolutely nothing to keep you from treating those 3 classes as just objects instead of JSON documents and storing those with a partition on Contact_id just as you would with MongoDB. However, if you had another object Account and you wanted to manage those in a non-embedded way because of some aggregate billing operations done on accounts, you can have that for free ( no need to create code for a DBRef type ) in the ODB ... and you can choose to partition right along with the Contact or choose to store the Accounts in a completely separate physical node, yet it will all be connected at runtime in the application space ... just like magic.

If you want to see a really cool video on how to create an application with an ODB which shows distribution, object movement, fault tolerance, performance optimization .. see this ( if you want to skip to the cool part, jump about 21 minutes in and you will avoid the building of the application and just see the how easy it is to add distribution and fault tolerance to any existing application ):

http://www.blip.tv/file/3285543

Answer 2

I think doc-oriented and object-oriented databases are quite different. Fairly detailed post on this here:

http://blog.10gen.com/post/437029788/json-db-vs-odbms