Relational databases are a great tool, but they are just one tool among many. If you have more data than fits on a single server and need a database that is highly available, then you should consider key/value data-storage. You may discover that they are a better fit for your needs.
Many key/value databases are designed to withstand multiple server and network failures, and to scale to dozens or hundreds of servers. In order to take advantage of that power you need to think differently about data modeling.
You will be amazed as to how much can be achieved with a key/value data store.
In this session, you will learn how to model your data to meet latency, scale and high-availability requirements using a high volume use-case of a mobile app that connects passengers with drivers of vehicles for hire, as well as coordinates ridesharing services.