Reverse data engineering technology for visual database design

Abstract The data engineer's inverse mapping problem of constructing, from a relational database schema (RDBS), a corresponding entity-relationship diagram (ERD), is studied. For going from extended ERDs to RDBS, there is a well known translation algorithm. The inverse direction is more difficult because many ERDs may correspond to one RDBS, and so it is not clear how to choose a most representative ERD. None the less, it would be desirable to be able to do so whenever possible, so that the benefits of entity-relationship (E-R)-based visual design can be applied to any RDBS. The paper presents a first demonstration prototype for the inverse mapping problem, for the case of an RDBS that was originally designed by an E-R-based tool and was then altered. A reverse translator (ReTro-ERDDS) tracks each atomic change in the RDBS and determines, via its Prolog E-R knowledge base, the corresponding changes in the original ERD, while preserving well formedness, a guarantor of normalization and robustness.