Why Relational Databases Aren't Good EnoughThe relational database model simply isn’t ideal for the dynamic needs of mobile applications. For one, traditional SQL databases use fixed schemas. This creates issues because with mobile applications, there are many situational requirements. As developers come up with new ideas and features for their applications, making changes becomes a time-consuming task because constant changes have to be made to the database schema.
For example, let’s say that a developer is creating an app similar to "Angry Birds," where different types of characters perform different actions. With a relational database, additions to the types of characters or actions they can perform might require altering the schema completely to accommodate the change. Depending on the size of the change, this could take a lot of time and effort on the developer’s end.
Another issue that relational databases have with regard to mobile applications is that they are not built to handle all of the different use cases mobile applications call for. The use cases can be broken down in terms of mobile device type, operating system, operating system firmware, and location. This becomes more complicated when you consider the different combinations that arise from users running outdated operating systems, traveling, and many other situations. Even a die-hard SQL advocate would have to admit that the relational database model isn’t as well suited for mobile applications.
Why NoSQL Is EffectiveNoSQL databases are designed to handle the dynamic needs of mobile applications. NoSQL databases do not use fixed schemas. So, in the example used above, adding new characters does not require developers to make drastic changes to the database. The developer would just be adding to the database rather than altering an existing schema.
I mentioned the different use cases that mobile applications must address. This is another issue that is fixed when using NoSQL databases. One of the best examples of NoSQL databases handling the complex use cases of mobile users is Foursquare. Because Foursquare is location based, the results users get from queries or even the options available to them will differ based on location. The geospatial capabilities of an open source NoSQL database such as MongoDB make it possible for developers to easily add location-aware features.
Another issue with mobile applications that NoSQL addresses is the need for constant updates. After an application has been released, maintenance becomes a major concern, among other things to consider. Because NoSQL is document based, fixing certain types of bugs and other problems doesn’t require a complete overhaul of the database, because the changes made by developers don’t necessarily affect every other aspect of the application.
Finally, NoSQL is well known for its scalability. Unlike relational databases, NoSQL databases scale outward rather than vertically. This is important because as the application’s user base grows, so will the amount of data being stored in the database. It’s important to have a growth strategy in place prior to developing an application because worrying about data constraints after the application has been released will result in downtime for maintenance and upset users.