A hierarchical method for synthesizing relations

Abstract

There are two basic approaches in the normalization theory of relational databases. One approach is the decomposition of large relation schemes into smaller relation schemes. A required criteria for a satisfactory decomposition is the lossless join property. The other approach is to synthesize a set of relation schemes from a given set of functional dependencies that are assumed to hold for a universal relation scheme. The synthesized relation schemes are easily identified once a minimal cover of the given set of functional dependencies is obtained. This paper presents another method for synthesizing relation schemes without finding a minimal cover. Starting with a given set of functional dependencies, a partial order graph can be defined. Using the partial order graph and any method for finding keys of relation schemes, a systematic method for synthesizing relation schemes is outlined. The method is easy to implement. However, no programming technique is suggested in this paper.