@inproceedings{www200944, booktitle = {18th International World Wide Web Conference}, month = {April}, title = {Improved Techniques for Result Caching in Web Search Engines}, author = {Qingqing Gan and Torsten Suel}, year = {2009}, pages = {431--431}, url = {http://www2009.eprints.org/44/}, abstract = {Query processing is a major cost factor in operating large web search engines. In this paper, we study query result caching, one of the main techniques used to optimize query processing performance. Our ?rst contribution is a study of result caching as a weighted caching problem. Most previous work has focused on optimizing cache hit ratios, but given that processing costs of queries can vary very signi?cantly we argue that total cost savings also need to be considered. We describe and evaluate several algorithms for weighted result caching, and study the impact of Zipf-based query distributions on result caching. Our second and main contribution is a new set of feature-based cache eviction policies that achieve signi?cant improvements over all previous methods, substantially narrowing the existing performance gap to the theoretically optimal (clairvoyant) method. Finally, using the same approach, we also obtain performance gains for the related problem of inverted list caching.} }