ORM Logic-Based English (OLE) and the ORM ReDesigner Tool: Fact-Based Reengineering and Migration of Relational Databases

The problem of database reengineering stems from (legacy) databases that are hard to understand (incorrect-, incomplete- or missing semantics) or that perform inefficiently. Reengineering is often cumbersome due to lack of semantics of the original database, and often the data migration target is also unclear. This paper addresses those two problems. We shall show how fact-based modeling, in particular ORM and its representation in (sugared) Sorted Logic, can help in reengineering (relational) databases. We reconstruct the semantics of the source database by offering a set of natural-language sentences capturing conceptual structure and constraints of the source. These sentences are written in a structured natural language format, coined as OLE: ORM Logic-based English. OLE is then used to define the mappings from the original source to a reengineered and restructured target database. We shall also discuss the ORMReDesigner: a semi-automatic tool, based on OLE and NORMA, available as a research prototype, used for reengineering and migrating relational databases.