Reevaluation of the storage of numerical fuzzy data in multidimensional indexes

The performance of a database system significantly depends on the application of suitable indexes. Integrating fuzzy sets in databases requires indexes which can handle that kind of data. One of the few variants concerning an indexing technique for fuzzy data manages the storage of numerical possibility distributions in multidimensional indexes. A subsequent analysis shows that the storage of fuzzy numbers in a B+tree, which is a standard index in most database systems, is the more preferable option. Due to some problematic assumptions in the aforementioned analysis, a reevaluation of that comparison is performed in this paper. In doing so, several modifications of the techniques are proposed and a comparison between B+trees and multidimensional indexes based on these modifications is examined. According to these examinations, a variant of the KDB-tree clearly outperforms the B+tree.