To be fair, there are a lot of places in the Linux kernel where primitive storage methods are used. In USB drivers, Vendor ID - Product ID pairs are stored in arrays. It's terrible and, most important, it doesn't scale. Being able to SELECT on a given VID would be really useful -- and it's really cool that MongoDB doesn't really impose too many constraints on the structure of your data.

Look, this hasn't been a good day so far, okay?