Using persistence technology to control schema evolution

Abstract

software engineering environments [13.14].Object-Oriented Datalgase Systems such,as GemStone [6] :~.d 02 [5] have at their Traditional database technology may be extended by takin~ core a persistent object store.Process modelling systems use a advantage of the facilities of an integrated persister, ~ persistent base to preserve their modellin,z activities over programming environment.This paper focuses on how such an environment may be used to provide new solutions to a long execu:io~ sessions [7].standing problem in traditional databases, that of schema Recen0y, integrated persis!ent programming systems have evolution A general mechanism is first described, followed by 19een develoPed that allow the complete software and data a description of a specific schema editing tool.process to take place entirely within the persistent The persistent environment provides an underlying technology environment [1~, 16].The facilities provided by traditional which allows the schema editor to locate and change, either databases may be extended by taking advantage of such an manually or automatically, all affected program and data.The environment In particular, this paper focuses on how the advantages of the mechanism are that it provides persistent environment may be used to provide new solutions to a long standing problem in tradi~iona!databases, that of understandable semantics for evolution by controlling when schema evolution A general mechanism is first described, the changes are made and by ensuring that changes to schema, followed by a description of a specific schema editin.~tool.The program and data are consistent and made in lock step.It is advantage of the mechanism is that it provides understandable shown how these changes together may be grouped as a semantics for evolution by controllinc, when the chan~es are transaction within a live system; furthermore, the ~ "accommodation of lazy data changes allows minimum loss of made and by ensuring that changes to schema, program and data availability, are consistent and made in lock step.