Adaptive query processing: Why, how, when, what next

There has been much work in recent years on adaptive query processing, especially in the context of emerging data management environments such as data integration and data streams. This has resulted in an overwhelming number of publications in last few years. Our goal is to give an overview of the work in this area, with a focus on identifying the common themes in this work, on clearly laying out the optimization space, and on discussing the open research problems. We plan to discuss why adaptive query processing is needed, different proposed techniques for doing it (the how), where this technology works and has the most potential for impact, and finally, what next, the open problems that still need further research. Copyright 2006 ACM.