On the efficient indexing of ordered multidimensional tuples

Multidimensional data structures are applied in many areas, e.g. data mining, indexing multimedia data and text documents, and so on. Therefore many index data structures and algorithms have been proposed. These data structures provide efficient processing of many types of queries like point and range queries. There are some applications where the range query result must be ordered. A typical case is the result with tuples sorted according to values in one dimension defined by the ORDER BY clause of an SQL statement. If we use a common multidimensional data structure, the result set is sorted after the range query is processed. Since the sort operation must often be processed on tuples stored in the secondary storage, an external sorting algorithm must be utilized. Therefore, this operation is time consuming especially for a large result set. In this paper, we introduce a new data structure, a variant of the R-tree, supporting a storage of ordered tuples. In this way, the range query result is ordered without an application of any time consuming sort operation. Our experiments show an improvement of this data structure compared to the R-tree.