Abstract not found

In presenting this thesis in partial fulfilment of the requirements for a Postgraduate degree

Abstract Supporting database schema evolution repre-sents a long-standing challenge of practical and theoretical importance for modern information systems. In this paper, we describe techniques and systems for automating the critical tasks of migrating the database and rewriting the legacy applications. In addition to labor saving, the ben-efits delivered by these advances are many and include reliable prediction of outcome, minimization of downtime, system-produced documentation, and support for archiving, historical queries, and provenance. The PRISM/PRISM++ system delivers these benefits, by solving the difficult prob-lem of automating the migration of databases and the rewrit-ing of queries and updates. In this paper, we present the PRISM/PRISM++ system and the novel technology that made it possible. In particular, we focus on the difficult and previously unsolved problem of supporting legacy queries and updates under schema and integrity constraints evolution. The PRISM/PRISM++ approach consists in providing the users with a set of SQL-based Schema Modification Opera-tors (SMOs), which describe how the tables in the old schema are modified into those in the new schema. In order to sup-port updates, SMOs are extended with integrity constraints