This is a false binary. It's not just using SQL vs using a Key/Value store. Caching/denormalization speeds up almost any algorithm; store a query result into

This is a false binary. It's not just using SQL vs using a Key/Value store. Caching/denormalization speeds up almost any algorithm; store a query result into memcached to make it even faster. Scale up and get the biggest box with the most RAM you can find, and if you can afford your entire dataset in 15 GB of RAM for $300/mo in a 3 year contract, congrats, use EC2 Extra Large and you're golden.