Efficient processing of skyline queries with partially-ordered domains

Many decision support applications are characterized by several features: (1) the query is typically based on multiple criteria; (2) there is no single optimal answer (or answer set); (3) because of (2), users typically look for satisfying answers; (4) for the same query, different users, dictated by their personal preferences, may find different answers meeting their needs. As such, it is important for the DBMS to present all interesting answers that may fulfill a user´s need. In this article, we focus on the set of interesting answers called the skyline. Given a set of points, the skyline comprises the points that are not dominated by other points. A point dominates another point if it is as good or better in all dimensions and better in at least one dimension. We address the novel and important problem of evaluating skyline queries involving partially-ordered attribute domains.