Improved caching policies and hybrid strategy for query result cache

To improve efficiency of search engines, the query result cache has drawn much attention recently. According to the query processing and user's query logs locality, a new hybrid result cache strategy which associates with caching heat and worth is proposed to compute cache score in accordance with cost-aware strategies. Exactly, query repeated distance and query length factor are utilized to improve the static result policy, and the dynamic policy is adjusted by the caching worth. The hybrid result cache is implemented in term of the document content and document ids(docIds) sequence. Based on a score format and the new hybrid structure, an initial algorithm and a new routing algorithm are designed for result cache. Experiments' results show that the improved caching policies decrease the average response time effectively, and increase the system throughput significantly. By choosing comfortable combination of page cache and docIds cache, the new hybrid caching strategy almost reduces more than 20% of the average query time compared with the basic page-only cache and docId-only cache.