In the recent days document databases get big buzz from all different areas: programmers who search for freedom or VCs who search for the next big buck. But there is a big disadvantage: the bigger the noise is the less the people using buzzwords like cloud or key-value store, understand whats behind. So let me start with a short disclaimer: I am not against key-value stores or any other document oriented database! But nonetheless I think it is required to clarify what a standard relational database can do, especially how powerful a language like SQL is. So lets clarify this by some examples and let me...