Datenbase Systems
Operations in Spatial Database Systems
During the last decade, the management of spatial data in geographic information systems (GIS) which are used in application areas such as geography, CAD/CAM, biology, medicine, etc. gaines increasing importance. Due to the high complexity of objects and queries and also due to the extremely large data volumes, geographic database systems impose stringent requirements on the employed storage and access structures.
Since spatial database systems are used in completely different application environments, it is not possible to find a compact set of operations fulfilling the requirements of all applications. We therefore distinguish three different classes of basic operations which should be efficiently supported in spatial database systems:
1. Update operations: insert, delete or modify.
2. Simple spatial selections are of great importance within the set of spatial queries and operations. An efficient implementation of spatial selections is an important requirement for good overall performance of a spatial database system.
The point query yields all objects which geometrically contain a query point.
The region query yields all objects sharing points with a query polygon. A special case of the region query is the window query. The query region of a window query is given by a rectilinear rectangle. Both, the window query and the region query are often called range queries.
The nearest neighbor query yields the closest object to a given query object.
3. Combination of object sets:
The spatial join computes all pairs of objects fulfilling a spatial predicate.
The map overlay geometrically combines two or more sets of objects.
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