Kelly Sommers has been commenting about transactional model on twitter. "Fully ACID writes but BASE reads" - Go back to the books. You can't selectively opt out of guarantees as you wish. What can client observe? And some other things in the same vien. I am going to assume that this is relevant for RavenDB, based on other tweetss from her. And I think that this requires more space than allowed on twitter. The gist of Kelly's argument, as I understand it, is that RavenDB isn't ACID because it does BASE reads.