Relational databases have pretty much ruled over the IT world for the last 30 years. However, Web 2.0 and the incipient Internet of Things (IoT) are some of the sources of a data explosion that has proved to exceed the limits of what modern relational databases can handle in a growing number of cases. As a result, new technologies had to be developed to handle these new use cases. We generally group these technologies under the umbrella of Big Data. In this two part presentation, we will start by understanding how relational databases have evolved to become the powerhouses they are today. In part 2 we will look at how non SQL databases are tackling the big data problem to scale beyond what relational databases can provide us today.