I have read a lot lately about 'NoSQL' databases such as CouchDB, MongoDB etc. Most of the websites I have seen using this are mainly text based websites such as The New York Times and Source forge.

I was wondering if you could apply this to websites where payment is a huge issue. I am thinking of the following issues:

• How well can you secure the data
• Do these system provide an easy backup/restore machanism
• How are transactions handled commit/rollback

I have read the following articles that cover some aspects:

• Can I do transactions and locks in CouchDB?
• Pros/Cons of document based database vs relational database

In these posts the aspect of transactions if covered. However the questions of security and backups is not covered. Can someone shed some light on this subject?

And if possible, does anyone know of some e-commerce websites that have successfully implemented the document based database.