3. The skyline query apparatus for performing a skyline query of claim 1 , wherein the data comprise at least one attribute having ordered values, and the processor is further configured to determine a leaf node of the quad tree, to which the data will belong, by splitting a space, which has the number of the attributes of the data indicated by the criteria contained in the skyline query as a dimension, once or more according to location of points represented by the data in the space.
3. The skyline query apparatus for performing a skyline query of claim 1 , wherein the data comprise at least one attribute having ordered values, and the processor is further configured to determine a leaf node of the quad tree, to which the data will belong, by splitting a space, which has the number of the attributes of the data indicated by the criteria contained in the skyline query as a dimension, once or more according to location of points represented by the data in the space. 5. The skyline query apparatus for performing a skyline query of claim 3 , wherein the processor is further configured to assign a bit string, which has the same length as the dimension of the space, as an ID of each of the split spaces.