Managing the History of Metadata in Support for DB Archiving and Schema Evolution

Abstract

Modern information systems, and web information systems in particular, are faced with frequent database schema changes, which generate the necessity to manage them and preserve the schema evolution history. In this paper, we describe the Panta Rhei Frameworkdesigned to provide powerful tools that: (i) facilitate schema evolution and guide the Database Administrator in planning and evaluating changes, (ii) support automatic rewriting of legacy queries against the current schema version, (iii) enable efficient archiving of the histories of data and metadata, and (iv) support complex temporal queries over such histories. We then introduce the Historical Metadata Manager (HMM), a tool designed to facilitate the process of documenting and querying the schema evolution itself. We use the schema history of the Wikipedia database as a telling example of the many uses and benefits of HMM.