are invariant under topological transformations like translation, scaling, and rotation (2) Direction relationships, for example, above, below, north_of, southwest_of, etc. The most representative spatial relationships are: (1) Topological relationships, such as adjacent, inside, disjoint, etc. Spatial Operators: Spatial operators represent the spatial relationships between spatial objects.

A spatial object is an object with at least one attribute of a spatial data type. Spatial Data Types: Spatial data types provide a fundamental abstraction for modeling the structure of geometric entities in space (geometry) as well as their relationships (topology), e.g. The answer is a set of pairs of objects from the two input datasets that are within distance d from each other, provided that the first object appears at least K times in the join result. Iceberg Distance Join: This spatial query involves two spatial datasets, a distance threshold d and a cardinality threshold K (K=1).

Spatial Query: It is a set of spatial conditions characterized by spatial operators that form the basis for the retrieval of spatial information from a spatial database system. Spatial Database System (SDBS): A spatial database system is a database system that offers spatial data types in its data model and query language and supports spatial data types in its implementation, providing at least spatial indexing and efficient spatial query processing. The answer is a set of pairs of spatial objects from the two input datasets that are within distance d from each other. Key Terms in this Chapterīuffer Query: This spatial query involves two spatial datasets and a distance threshold d.

From the query processing point of view, the following three properties characterize the differences between spatial and relational databases (Brinkhoff et al., 1993): (1) unlike relational databases, spatial databases do not have a fixed set of operators that serve as building blocks for query evaluation (2) spatial databases deal with extremely large volumes of complex objects, which have spatial extensions and cannot be sorted in one dimension (3) computationally expensive algorithms are required to test the spatial operators, and the assumption that I/O costs dominate CPU costs is no longer valid.

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