K-Relations and Beyond

Although the theory of relational databases is highly developed and proves its usefulness in practice every day Garcia-Molina et al. (2008), there are situations where the relational model fails to offer adequate formal support. For instance, when querying approximate data Hjaltason & Brooks (2003); Minker (1998) or data within a given range of distance or similarity Hjaltason & Brooks (2003); Patella & Ciaccia (2009). Examples of such similarity-search applications are databases storing images, fingerprints, audio clips or time sequences, text databases with typographical or spelling errors, and text databases where we look for documents that are similar to a given document. A core component of such cooperative systems is a treatment of imprecise data Hajdinjak & Mihelič (2006); Minker (1998).