Isn't that what Oracle RAC is for? If you are managing that much data, and you don't want to go the specialty DB route (nosql, for example) RAC scales.
It's also hellishly complicated, but so is the problem.
Right I feel like some times when someone say relational databases don't scale they mean that free databases don't scale without a lot of work. Scaling with Oracle is fast and easy (in comparison to the alternatives), it is why people still pay that kind of money for it. I personally find Oracle the company distasteful but the facts are the facts and Oracle does scale.
Sometimes I wonder... if three fortune 500 companies just spent the same amount as their Oracle budget on Postgres devs, they could probably have a RAC competitor in three years.
Then, just another billion on transition costs, right? :)
I agree, there is no technical reasons that postgres could not be as easy or as good at scaling as Oracle. Someone just has to put the money and effort in.
It's also hellishly complicated, but so is the problem.