Spatio-Temporal Data Types: An Approach to Modeling and Querying Moving Objects in Databases

Martin Erwig (1), Ralf Hartmut Güting (1), Markus Schneider (1), Michalis Vazirgiannis (1+2)
 (1) Praktische Informatik IV, Fernuniversität Hagen, D-58084 Hagen, GERMANY,
{erwig, gueting, markus.schneider}
(2) Dept. of Informatics, Athens University of Economics and Business,
Patision 76, 10434 Athens, Greece,
 Abstract: Spatio-temporal databases deal with geometries changing over time. In general, geometries cannot only change in discrete steps, but continuously, and we are talking about moving objects. If only the position in space of an object is relevant, then moving point is a basic abstraction; if also the extent is of interest, then the moving region abstraction captures moving as well as growing or shrinking regions. We propose a new line of research where moving points and moving regions are viewed as three-dimensional (2D space + time) or higher-dimensional entities whose structure and behaviour is captured by modeling them as abstract data types. Such types can be integrated as base (attribute) data types into relational, object-oriented, or other DBMS data models; they can be implemented as data blades, cartridges, etc. for extensible DBMSs. We expect these spatio-temporal data types to play a similarly fundamental role for spatio-temporal databases as spatial data types have played for spatial databases. The paper explains the approach and discusses several fundamental issues and questions related to it that need to be clarified before delving into specific designs of spatio-temporal algebras.

 Keywords: Spatial, temporal, spatio-temporal, data types, moving objects, moving point, moving region

 Published: FernUniversität Hagen, Informatik-Report 224, December 1997. To appear in GeoInformatica 3:3, 1999.