Proceedings of the Eleventh International Conference on Data Engineering (1995)
Mar. 6, 1995 to Mar. 10, 1995
C. Kalus , Fak. fur Inf., Ulm Univ., Germany
P. Dadam , Fak. fur Inf., Ulm Univ., Germany
The model of flexible relations supports heterogeneous sets of tuples in a strongly typed way. The elegance of the standard relational model is presented by using a single, generic scheme constructor. In each model supporting structural variants the shape of some part of a heterogeneous scheme may be determined by the contents of some other part of the scheme. We formalize this relationship by a certain kind of integrity constraint we have called "attribute dependency" (AD). We motivate how ADs can be used, besides their application in type and integrity checking, to incorporate record subtyping into our extended relational model. Moreover, we show that ADs yield a stronger assertion than the traditional record subtyping rub as they consider interdependencies among refinements. We discuss how ADs are related to query processing and how they may help to identify redundant operations.
data structures; relational databases; entity-relationship modelling; data integrity; query processing; database theory; record subtyping; flexible relations; attribute dependencies; heterogeneous sets; tuples; standard relational model; generic scheme constructor; heterogeneous scheme; integrity constraint; attribute dependency; integrity checking; type checking; extended relational model; query processing; redundant operations
C. Kalus and P. Dadam, "Record subtyping in flexible relations by means of attribute dependencies," Proceedings of the Eleventh International Conference on Data Engineering(ICDE), Taipei, Taiwan, 1995, pp. 383.