On database query languages for K-relations

The relational model has recently been extended to so-called K-relations in which tuples are assigned a unique value in a semiring K. A query language, denoted by RAC K , similar to the classical positive relational algebra, allows for the querying of K-relations. In this paper, we define more expressive query languages for K-relations that extend RAC K with the difference and constant annotations operations on annotated tuples. These operations are natural extensions of the difference and duplicate elimination operations in the relational algebra on sets and bags, respectively. We investigate conditions on semirings under which these operations can be added to RAC K in a natural way, and establish basic properties of the resulting query languages. Moreover, we show how the provenance semiring of Green et al. can be extended to record provenance of data in the presence of difference and constant annotations. Finally, we investigate the completeness of RAC K and extensions thereof in ...

• Type: Journal
• Year: 2010
• Where: JAPLL
• Authors: Floris Geerts, Antonella Poggi
• Keywords: Constant Annotations, JAPLL 2010, Query Languages, Relational Algebra