Query rewriting in spatial database for access control

Abstract

Current database with numerous users requires access control. It is also needed in spatial database systems that keep both spatial attribute and non-spatial attribute safe. The query rewriting technology in spatial database is discussed in this paper. First the operations for merging authorization policies are discussed. By classifying the subjects and permit flag of the authorization policies, two operations, both intersection and union, are discussed with different purpose. And an algorithm for merging user's authorization policies is prompted. Then a view based query rewriting method is set up by replacing the all relations in the query with the corresponding view. That makes sure the finegrained access control for the spatial database and spatial objects. Finally, a spatial database as an application is given to validate the effectiveness of query rewriting technology in spatial database.