The first thing you need to realize is that you're a victim of the SQL hammer. If having a hammer means everything is a nail, then it's the same for SQL. Imagine, for instance, that Google's search engine (which is trying to deliver information that is personal and relevant to you) was built by a group of SQL engineers. First, they would have designed a global data schema for all the information on the planet. Then they would have used the extract, transform and load (ETL) process and data-cleansing tools to bring all the information on the planet into their global SQL database. Finally, they would write reports such as: "Places to camp in France," or "Chinese restaurants in Hickory, N.C." After 10 years and tens of millions of dollars, the team would probably have given up. Fortunately, Google didn't take that approach.
via NoSQL databases