What open source document-oriented database system is most mature for Windows usage?

After using relational databases as back-end storage all my Windows programming life (currently .NET), I want to experiment with a docume开发者_Python百科nt-oriented database by this Wikipedia definition; it can be standalone or layered over an existing non-commercial database system.

What open source document-oriented database solution would you recommend from your own Windows programming experience and why? (Reason for open-source is to keep it on the cheap, also because open source is often darn good and on the leading edge.)

A nice to have would be a .NET provider to connect with.

Ultimately the chosen system might be rolled into a real solution if everything works out well.

Admittedly this is somewhat subjective and potentially argumentative so keep it real folks and I'll do the same - also your answers will be invaluable to others looking into document-oriented databases for the first time on Windows. I'm sure the overall value of your answers will outweigh any biases.

Thanks.

I work on the C# mongodb driver at http://github.com/samus/mongodb-csharp/. I really enjoy working with MongoDB because it has some features from a relational engine like dynamic queries and indexes that makes it easier to transition to than the other contenders (CouchDB, RavenDB, etc...)

The MongoDB-CSharp driver has great Linq support so that will also make the transition easier. You can see some of the not-yet-finished documentation here -> http://wiki.github.com/craiggwilson/mongodb-csharp/.

RavenDB by Ayende is probably the most mature Windows product because it's the only one (that I know of) that is actually written in .net and "just works" under Windows.

Then again, it's only free if you use it in open source projects. If you use it in closed source projects, you have to buy a commercial license (see the licensing info).
Since you want open source because it's cheap, I don't know if it's interesting for you then.

There's a lot more information about it on Ayende's blog.