Interactions between dependencies and nested relational structures

摘要

Nesting is a way of transforming a first-normal-form relation into a structure with set-valued entries in some positions instead of atomic entries. In this paper we study how functional and multivalued dependencies interact with nesting. We describe how nesting preserves, alters, or destroys dependencies holding in a first-normal-form relation. We then consider dependencies which hold in each block of the horizontally decomposed relation induced by nesting and study the relationship between these “local” dependencies and “global” dependencies in the normalized relation.