Why do we keep jumping from one storage engine to another? Can't we make up our minds already and settle with the "best" storage engine that meets our needs? In short, No. A common misconception is the belief that all storage engines are created equal, all designed to simply "store stuff" and provide fast access to your data. Unless your application performs one clearly defined simple task, it is a dire mistake to expect a single storage engine will effectively fulfill all of your data warehousing and processing needs.
via NoSQL databases