Modelling and Managing Time in Database Systems
D. H. O. Ling, David Bell · The Computer Journal · 1992
This paper describes a new architecture for a system to handle temporal data, called Temporal Data Management System, TDMS. TDMS represents an approach to the modelling of temporal semantics which is pragmatic because it takes into account practical issues such as the time/space trade-offs. We consider the technical aspects of the system i.e. how time domain data is managed in TDMS. The design of temporal databases is not addressed here. We introduce a conceptual framework which permits issues such as handling schema anomalies due to updates, query validation and correct semantics modelling to be handled in a consistent and usable manner. It incorporates the time values of each of three ‘data constructs’ organised in a hierarchy. This is combined at the implementation level with a well-established multi-database architecture to give a comprehensive and efficient temporal model which overcomes several weaknesses of current temporal models. Modest extensions to the SQL syntax to handle time are proposed and have been implemented. Both tuple-stamping and value-stamping are provided by the integration of TDMS and the relational data model. TDMS has been prototyped under the UNIX operating system using the C programming language. Presently, TDMS interfaces with the Ingres DBMS.