Sven Hartmann
Decomposition by pivoting and path cardinality constraints
Preprint series: Preprints aus dem Fachbereich Mathematik, Universität Rostock
68P15 Database theory
68R10 Graph theory, See also {05Cxx, 90B10, 90B35, 90C35}
Abstract: In the relational data model, the problem of data
redundancy has been successfully tackled via decomposition. In
advanced data models, decomposition by pivoting provides a similar
Pivoting has been introduced by Biskup et al.,
and used for decomposing relationship types according
to a unary nonkey functional dependency. Our objective is to study
pivoting in the presence of cardinality constraints which are commonly
used in semantic data models.

In order to ensure the equivalence of the given schema and
its image under pivoting, the original application-dependent
constraints have to be preserved. We discuss this problem for sets of
participation and co-occurrence constraints. In particular, we prove
the necessity of path cardinality constraints, and give an appropriate
foundation for this concept.
Keywords: decomposition; pivoting; cardinality constraint; functional dependency;