The data center is rapidly becoming a victim of its own success. The increasingly low-price-to-performance-ratio of modern computers has meant that many data centers are now bursting with machines.
Unfortunately, these machines all require power, cooling, cabling, and ultimately some level of tender loving care from an IT manager.
The database server is one type of machine that has traditionally resided in the data center. The advent of the open source database such as Derby may allow for a slightly lower reliance on big database servers.
In effect, Derby can live on the most modest of computing platforms well outside the data center.
There are, of course, mission-critical applications that require 24/7 support, and it is highly unlikely that the data requirements for these applications will not remain rooted in the data center indefinitely.
Smaller, less-critical applications can host their own database engines by using Derby. This has the interesting dual effects of reducing the strain on the data center (by moving one database out of the data center) while also starting to democratize the area of database programming.
The code required to build a simple Derby database is very straightforward. I haven’t covered the areas of database design (for example, normalization, entity-relation modeling, and so on) in this article.
But you can argue that for small applications, it’s not strictly necessary to use them. Particularly if you’re new to the area of database development and you’re trying to find your feet.
I always believe in helping programmers to move up the value chain. This is a topic I discuss at length in my eBook (see  in the following "References" section) and recent article (see  in the following "References" section).
So, give Derby a go!