Incremental Restructuring of Relational Schemas

摘要

Schema restructuring is part of both database design and database reorganization, which are expressions of the specification and evolution of information systems. Entity-Relationship (ER) Consistency expresses the capability of relational databases to model information oriented systems. A relational schema consisting of relation-schemes together with key and inclusion dependencies is said to be ER-consistent if it complies with an entity-relationship structure, meaning that it is representable by an ER-Diagram. Restructuring of ER-consistent schemas consists of the addition and removal of relation-schemes, together with the adjustment of key and inclusion dependencies. Smooth schema modification is characterized by incrementality and reversibility. We propose a complete set of incremental and reversible restructuring manipulations for ER-consistent relational schemas. We show how the set of schema restructuring manipulations proposed by us back both interactive and view-integration methodologies for schema design. 13 refs., 9 figs. (ERA citation 13:032043)