Admission polices for outperforming the efficiency of search engines

We study the caching of query result pages in Web search engines. Popular search engines receive millions of queries per day, and efficient policies for caching query results may enable them to lower their response time. In this paper, we propose an architecture that uses a combination of cache result and admission policy to improve the efficiency of search engines. In our system, we divide the cache into two layers to ensure the high hit ratio of the cache. We propose a admission policy to prevent infrequent queries from taking space of more frequent queries in the cache. We also introduce new eviction policy to update the result cache, which is more general than traditional heuristics such as LRU. We experiment with real query logs and a large document collection, and show that the hybrid cache enables efficient reduction of the query processing costs and thus is practical to use in Web search engines.