Nathan Ong, Stephen Rojcewicz, Dr. Nicholas Farnan, Dr. Adam Lee, Dr. Chrysanthis, Dr. Ting Yu (North Carolina State University) have a demo entitled "Interactive Preference-Aware Query Optimization" in ICDE 2015 in Seoul, South Korea.
Link

Abstract:
PASQL is an extension to SQL that allows users of a distributed database to specify privacy constraints on an SQL query evaluation plan. However, privacy constraints can be difficult for users to specify, and worse yet, all possible situations that could lead to a privacy violation may not be known to the user a priori. To address these challenges, we propose a GUI-based interactive process for detecting such violations and generating appropriate constraints. In this work, we demonstrate two approaches to implementing such a GUI that provide different ways of analyzing and interactively optimizing a PASQL query plan.