In this paper, we present the findings of a large study of the evolution of the schema of 195 Free Open Source Software projects. We identify families of evolutionary behaviors, or taxa, in FOSS projects. A large percentage of the projects demonstrate very few, if any, actions of schema evolution. Two other taxa involve the evolution via focused actions, with either a single focused maintenance action, or a large percentage of evolution activity grouped in no more than a couple interventions. Schema evolution also involves moderate, and active evolution, with very different volumes of updates to the schema. To the best of our knowledge, this is the first study of this kind in the area of schema evolution, both in terms of presenting profiles of how schemata evolve, and, in terms of the dataset magnitude and the generalizability of the findings.
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A 12' video presentation is available as a youtube video.