Independent and Separable Database Schemes
Edward P. F. Chan, Alberto O. Mendelzon · SIAM Journal on Computing · 1987
We propose and investigate the notion of separability to capture the design goal of independently updatable decompositions. We characterize separable schemes in the important case when the only constraints given are a set of functional dependencies and the join dependency $\bowtie {\bf R}$. This characterization is also applicable to cover embedding database schemes when a set of functional dependencies is given as constraint. As evidence in favor of separability as a natural concept of independence, we show that it is equivalent to a specialization of the abstract independent mappings defined by Bancilhon and Spyratos. Our characterization yields a polynomial-time algorithm for testing separability in these cases.