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Please use this identifier to cite or link to this item: http://hdl.handle.net/2451/14525

Title: THE HISTORICAL RELATIONAL DATA MODEL (HRDM) AND ALGEBRA BASED ON LIFESPANS
Authors: Clifford, James
Croker, Albert
Issue Date: Jun-1986
Publisher: Stern School of Business, New York University
Series/Report no.: IS-86-19
Abstract: Critical to the design of an historical database model is the representation of the “existence” of objects across the temporal dimension -- for example, the "birth," "death," or "rebirth" of an individual, or the establishment or dis-establishment of a relationship. The notion of the "lifespan" of a database object is proposed as a simple framework for expressing these concepts. An object's lifespan is simply those periods of time during which the database models the properties of that object. In this paper we propose the historical relational data model (HRDM) and algebra that is based upon lifespans and that views the values of all attributes as functions from time points to simple domains. The model that we obtain is a consistent extension of the relational data model, and provides a simple mechanism for providing both time-varying data and time-varying schemes.
URI: http://hdl.handle.net/2451/14525
Appears in Collections:IOMS: Information Systems Working Papers

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