TBH we are at around 15M queries per hour. I am sure our customers don't want us to run on RPi. Btw, it's not only query but billion+ rows which are also there.
I expected as much, usually it's me pointing out that mongodb is a decent DB depending on the data you're ingesting/storing, and it's builtin clustering is significant better then what postgres offers at the moment.
But the number was so low I couldn't help but point out that this was more likely to convince me that mongo is a joke then a usable database
So I think my point still stand: that number is as low as you can get for any rdbms.