An Introduction to Spatial Database Systems Ralf Hartmut Güting Praktische Informatik IV, FernUniversität Hagen D-58084 Hagen, Germany gueting@fernuni-hagen.de Abstract: We propose a definition of a spatial database system as a database system that offers spatial data types in its data model and query language and supports spatial data types in its implemen- tation, providing at least spatial indexing and spatial join methods. Spatial database systems offer the underlying database technology for geographic information systems and other applications. We survey data modeling, querying, data structures and algorithms, and system architecture for such systems. The emphasis is on describing known technology in a coherent manner rather than on listing open problems. Invited Contribution to a Special Issue on Spatial Database Systems of the VLDB Journal (Vol. 3, No. 4, October 1994) September 1994