Extensible and similarity-based grouping for data integration

The general concept of grouping and aggregation appears to be a fitting paradigm for various issues in data integration, but in its common form of equality-based grouping, a number of problems remain unsolved. We propose a generic approach to user-defined grouping as part of a SQL extension, allowing for more complex functions, for instance integration of data mining algorithms. Furthermore, we discuss high-level language primitives for common applications.