On getting some answers quickly, and perhaps more later

Traditionally, the answer to a database query is construed to be the set of all tuples that meet the criteria stated. Strict adherence to this notion in query evaluation is, however, increasingly unsatisfactory, because decision makers are more prone to adopting an exploratory strategy for information searching, which we call “getting some answers quickly, and perhaps more later”. In this paper, we propose a progressive query processing strategy that exploits this behavior to conserve system resources and to minimize query response time. This is accomplished by the heuristic decomposition of user queries into subqueries that can be evaluated on demand. We also describe the architecture of a prototype system that provides a non-intrusive implementation of our approach. Finally, we present experimental results that demonstrate the benefits of the progressive query processing strategy