The choice of data structure is an important decision in any software project. Application developers do not necessarily have a good understanding of how a particular system manages its data structures and how this might influence performance. We provide visualisations representing the behaviour of different data structures in an object oriented distributed database system. The data is obtained from cache monitoring software and the visualisations therefore represent the actual, as opposed to the theoretical, behaviour. The visualisations can be used as a supplement to the textual description of how a particular system manages its data structures so providing developers, educators and students with a clearer understanding of the implications of their choice of data structure.