User defined topological predicates in database systems

Current database systems cannot only store standard data like integer , string , and real values, but also spatial data like points , lines, and regions . The importance of topological relationships between spatial objects has been recognized a long time ago. Using the well known 9 intersection model for describing such relationships, a lot of constellations can be distinguished. For the query language of a database system it is not desirable to have such a large number of topological predicates. Particularly the query language should not be extended by a large number of topological predicates. This paper describes how a database system user can define and use her own topological relationships. We show algorithms for computing user defined topological predicates in an efficient way. Last, we compare these general versions with specialized implementations of topological predicates.