On Completeness of Historical Relational Data Models

Several proposals for extending the relational data model to incorporate thetemporal dimension of data have appeared in the past several years. Theseproposals have differed considerably in the way that the temporal dimensionhas been incorporated both into the structure of the extended relations thatare defined as part of these extended model, and into the operations of theextended relational algebra or calculus component of the models. Becauseof these differences it has been difficult to compare the proposed models andto make judgements as to which of them is "better" or indeed, the "best."In this paper we propose a notion of historical relational completeness,analogous to Codd's notion of relational completeness, and examine severalhistorical relational proposals in light of this standard.