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A Well-Specified Temporal Relational Model

A temporal extension of the relational model is proposed in this paper. Existing temporal relational models are analyzed in order to answer some of the unresolved issues of this topic. The basic relational operations are redefined as consistent extensions of the existing operations in a manner that preserves the basic algebraic equivalences of the snapshot (i.e., conventional static) algebra. The proposed model is evaluated using a set of twenty-six criteria proposed by McKenzie and Snodgrass (199la) and compared to three existing models. Our model appears to be superior to the others. In addition, some of the complexities associated with supporting the time domain are analyzed and the role of a temporal DBMS outlined.