Justify that with actual math, please? I don't think you know how computers (processors, bus, memory access, etc) work. How exactly do you think an RDBMS can query an index at a hundred billion rows per second?
Like Illniyar, that's also what I interpreted GP to mean when they said:
> "surprised that some NoSQL DB could do a query on hundred million rows in a few seconds"
which is not fast at all. However, if it actually did something on a hundred million rows that would be impressive. Not sure exactly sure which they meant, though.
Even better, if you only need one field from the record, and it's part of a compound index, you can frequently return the data from just the indexes; no disk seeks required. Small tip with InnoDB on MySQL - any non-primary key index is automatically a compound index with the primary key.