PURPOSE: A method for processing ranking queries is provided to efficiently perform query processing by searching for top tuples according to a path based on relations between tuples. CONSTITUTION: A skyline for tuple sets is obtained(S320). A relation is set by deriving tuples of other skylines(S330). A convex skyline of the skyline is obtained(S340). The relation is set by deriving tuples of other convex skylines(S350). [Reference numerals] (AA) Start; (BB) End; (S310) Input tuple sets; (S320) Obtain a skyline for the tuple sets(Repeat until all tuples are obtained as skylines); (S330) Set the relation of each tuple of each skyline with the tuble of other skylines on which the tuple depends; (S340) Obtain a convex skyline of each skyline; (S350) Set the relation of each tuple of each convex skyline with the tuple of other convex skyline on which the tuple depends
