Real-world MVD's
Edward Sciore · 1981
According to database theory, a database designer can specify any set of data dependencies, no matter how complex, to constrain a database scheme. This paper investigates how much complexity is actually needed in real-world situations. It is shown that every "natural" set of mvd's must belong to a class of mvd's called conflict-free. Conflict-free sets of mvd's have the desirable property that they allow a unique 4NF dependency preserving database scheme; moreover, non conflict-free sets have no such normalization. If a set of mvd's is not conflict-free, then the dependencies are inadequately specified; there are semantic concepts that are unrepresented in the scheme. These concepts are isolated, and it is shown that adding these concepts amounts to making the set of mvd's conflict-free.