Data design is an essential part of the application development cycle. By analogy, building an application is like building a house. Having the right tools is important, but we need a solid foundation: the data structure. However, producing a good data structure can be a daunting challenge; the quest for a perfect data structure can lead us to new territories where many methods are available. Which one is the best? How can we keep our focus on the goal to achieve, without losing our time?