I don't think that the schema here allows you to do this kind of query even in MySQL. They are throwing everything in that blob, which makes it pretty difficult

I don't think that the schema here allows you to do this kind of query even in MySQL. They are throwing everything in that blob, which makes it pretty difficult to sort on anything that's in the blob. So, I think they would have to do what you are describing, denormalize everything... or get all the data and do the sort in the app. Which is precisely what would be required with Cassandra or another NoSQL system. Am I missing anything that would invalidate what I've just said?