Is there a database like this?

Question

Background: Okay, so I'm looking for what I guess is an object database. However, the (admittedly few) object databases that I've looked at have been simple persistence layers, and not full-blown DBMSs. I don't know if what I'm looking for is even considered an object database, so really any help in pointing me in the right direction would be very appreciated.

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I don't want to give you two pages describing what I'm looking for so I'll use an example to illustrate my point. Let's say I have a "BlogPost" object that I need to store. Something like this, in pseudocode:

class BlogPost
    title:String
    body:String
    author:User
    tags:List<String>
    comments:List<Comment>

(Assume Comment is its own class.)

Now, in a relational database, author would be stored as a foreign key pointing to a User.id, and the tags and comments would be stored as one-to-many or many-to-many relationships using a separate table to store the relationships. What I'd like is a database engine that does the following:

• Stores related objects (author, tags, etc.) with a direct reference instead of using foreign keys, which require an additional lookup; in other words, objects on top of each other should be natively supported by the database
• Allows me to add a comment or a tag to the blog post without retrieving the entire object, updating it, and then putting it back into the database (like a document-oriented database -- CouchDB being an example)

I guess what I'm looking for is a navigational database, but I don't know. Is there anything even remotely similar to what I'm thinking of? If so, what is it called? (Or better yet, give me an actual working database.) Or am I being too picky?

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Edit:

Just to clarify, I am NOT looking for an ORM or an abstraction layer or anything like that. I am looking for an actual database that does this internally. Sorry if I'm being difficult, but I've searched and I couldn't find anything.

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Edit:

Also, something for the JVM would be excellent, but at this point I really don't care what platform it runs on.

Answer 1

I guess you're looking for an ORM with "EntityFirst" approach.

In EntityFirst approach the developer is least[not-at-all] concerned with Database. You just have to build your entities or objects. The ORM then takes care of storing the entities in Database and retrieving them at your will.

The only EntityFirst ORM witihn my knowledge "Signum". It's a wonderful framework built on top of .net. I recommend you to go thrgouh some videos on the SignumFramework website and I'm sure you'll find it useful.

Link Text: http://www.signumframework.com

Thanks.

Answer 2

Oracle's nested tables provide some part of that functionality, though in updates, you cannot just add a row to the nested table - you have to replace the whole nested table.

Answer 3

You could try out db4o which is available in C# and Java.

Answer 4

There's a variety of terms, all linked to Object-Relational Mapping, aka ORM, which is probably going to be the most useful one for you to look up. ORM libraries exist for many programming languages.

Answer 5

Elephant does this: http://common-lisp.net/project/elephant/