Introduction to Preference Query Analysis and Optimization

Abstract

Preference query is one of the important queries in database community. Currently, the preference query only returns the query results to users. If the query result is unexpected for the users, the database system neither gives explanations for the unexpected query results, nor offers any suggestion on how to get the expected results for users. If the database system can offer such explanations and suggestions through query analysis and optimization, it helps the users understand initial query better. Toward this, the studies on preference query analysis and optimization have been explored. In this chapter, we introduce the concepts of (i) query analysis and optimization, which includes three aspects, i.e., causality and responsibility problem, why-not and why questions, why-few and why-many questions, and (ii) the preference query, which includes quantitative preference query and qualitative preference query. Then, we present the research issues and challenges for preference query analysis and optimization.