Facilitating Database Attribute Domain Evolution Using Mesodata

Database evolution can be considered a combination of schema evolution, in which the structure evolves with the addition and deletion of attributes and relations, together with domain evolution in which an attribute’s specification, semantics and/or range of allowable values changes. We present a model in which mesodata – an additional domain definition layer containing domain structure and intelligence – is used to alleviate and in some cases obviate the need for data conversion or coercion. We present the nature and use of mesodata as it affects domain evolution, such as when a domain changes, when the semantics of a domain alter and when the attribute’s specification is modified.