Choosing a View Update Translator by Dialog at View Definition Time
Arthur M. Keller · 1986
ABSTRACT. We consider the problem of updating databases through views composed of selections, projections, and joins of a series of Boyce-Codd Normal Form relations. This involves translating updates expressed against the view to updates expressed against the database. Previously, we enumerated all translations of view updates into database updates that satisfy five criteria. This enumeration shows that the problem of translating view updates to database updates is inherently ambiguous. We give examples of structurally similar views that should have different translations because of the real world semantics. We propose that these semantics be obtained at view definition time. We show how this can be done through a structured dialog with the database administrator to choose a view update translator at view definition time. The questions asked during this dialog are based on the view definition, database structural schema information, and the answers to earlier questions in the dialog. Based on these questions a specific translator is chosen. Using this translator, userspecified view updates can be translated into database