Vertical and horizontal percentage aggregations

摘要

Existing SQL aggregate functions present important limitations to compute percentages. This article proposes two SQL aggregate functions to compute percentages addressing such limitations. The first function returns one row for each percentage in vertical form like standard SQL aggregations. The second function returns each set of percentages adding 100% on the same row in horizontal form. These novel aggregate functions are used as a framework to introduce the concept of percentage queries and to generate efficient SQL code. Experiments study different percentage query optimization strategies and compare evaluation time of percentage queries taking advantage of our proposed aggregations against queries using available OLAP extensions. The proposed percentage aggregations are easy to use, have wide applicability and can be efficiently evaluated.