Elimainating Polyimstantation in Multilevel Relational Databases

Abstract

In a relational database with multilevel relations, polyinstantiation results from avoiding a downward signaling channel. However, it also results in the cover story, data redundancy and need of update propagation. In this paper, we propose a new polyinstantiation elimination scheme to simultaneously solve the problems of the cover story, data redundancy and need of update propagation in the multilevel relation. This proposed scheme is based on a decomposition method to decompose a multilevel relation into several subrelations according to the lowst visible security level of a data attribute and whether the data attribute can be permitted to ignore the signaling channel. The algorithm and an analysis of this scheme are also presented in this paper.