On the completeness of object-creating database transformation languages

Abstract

Object-oriented applications of database systems require database transformations involving nonstandard functionalities such as set manipulation and object creation, that is, the introduction of new domain elements. To deal with these functionalities, Abiteboul and Kanellakis [1989] introduced the "determinate" transformations as a generalization of the standard domain-preserving transformations. The obvious extensions of complete standard database programming languages, however, are not complete for the determinate transformations. To remedy this mismatch, the "constructive" transformations are proposed. It is shown that the constructive transformations are precisely the transformations that can be expressed in said extensions of complete standard languages. Thereto, a close correspondence between object creation and the construction of hereditarily finite sets is established. A restricted version of the main completeness result for the case where only list manipulations are involved is also presented.