Association for Computing Machinery
SQL presents limitations to return aggregations as tables with a horizontal layout. A user generally needs to write separate queries and data definition statements to combine transposition with aggregation. With that motivation in mind, the authors introduce horizontal aggregations, a complementary class of aggregations to traditional (vertical) SQL aggregations. The SQL syntax extension is minimal and it significantly enhances the expressive power and ease of use of SQL. Their proposed SQL extension blurs the boundary between row values and column names. They present a prototype query optimizer that can evaluate arbitrary nested queries combining filtering, joins and both classes of aggregations.