Towards supporting hard schema changes in TSE

Software Language Evolution

“…Only for capacity-increasing changes, the actual database schema is changed. Besides the set of primitive changes known from other approaches, TSE was extended to handle more complex changes [Ra and Rundensteiner, 1995a].…”

“…Views are an integral part of many database systems and are commonly used to continuously support different versions of a schema [Liu et al, 1993, 1994, Ra and Rundensteiner, 1995a,b, 1997, Crestana-Jensen et al, 2000, or to support coupled evolution without having to change or recreate the original database [Tresch andScholl, 1993, Brèche et al, 1995]. In modelware, grammarware and XMLware, (editable) views are not widely used, hence their application to coupled evolution is lacking.…”

Consistent schema version removal: an optimization technique for object-oriented views

“…Systems that enable interoperability for multiple software applications in dynamic environments must allow applications to evolve and flexibly change their data requirements, while minimizing or even eliminating the impact of such change on other existing applications. Several approaches [3,11,15,17,18] have been proposed to support schema evolution and/or data integration needs by using object-oriented views. Nevertheless, these approaches run into a potential problem of generating a large number of schema versions over time resulting in an excessive build-up of classes and underlying object instances, not all being necessarily still in use.…”

“…In transparent schema evolution systems [17,18,21], each user 3 constructs a customized interface by selecting a subset of classes from the shared database. All the schema change requests made by the developer are issued against her customized view schema with which she is familiar (Figure 1(a)).…”

“…This example shows one of the schema change operators supported by the TSE system, namely the delete-attribute operator. A description of how view schemas are derived from the GS can be found in [13,19], and a complete reference on the schema change operators supported by the TSE system can be found in [17,18].…”