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大规模船舶数据库优化和查询研究 被引量:2
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作者 李淑娣 《舰船科学技术》 北大核心 2019年第4期142-144,共3页
船舶数据库优化和查询结果好坏直接影响船舶信息管理系统的性能,针对当前单一方法无法有效实现大规模船舶数据库优化和查询问题的求解,为了加快船舶数据库优化和查询效率,设计了基于组合理论的船舶数据库优化和查询方法。首先分析国内... 船舶数据库优化和查询结果好坏直接影响船舶信息管理系统的性能,针对当前单一方法无法有效实现大规模船舶数据库优化和查询问题的求解,为了加快船舶数据库优化和查询效率,设计了基于组合理论的船舶数据库优化和查询方法。首先分析国内外当前船舶数据库优化和查询研究现状,找到当前船舶数据库优化和查询方法存在的局限性,然后采用粒子群算法对大规模船舶数据库优化和查询问题进行求解,然后在此基础上,引入蚁群算法进行大规模船舶数据库优化和查询问题进一步求解,最后与单一方法进行船舶数据库优化和查询对比实验,结果表明,本文方法的船舶数据库优化和查询速度快,可以在短时间内找到用户需要的信息,而且船舶数据库查询精度更高,是一种性能优异的船舶数据库优化和查询方法。 展开更多
关键词 信息管理系统 数据库查询 组合理论 查询精度 平均查询时间
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Improved caching policies and hybrid strategy for query result cache
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作者 钱立兵 Ji Zhenzhou Bai Jun 《High Technology Letters》 EI CAS 2015年第3期339-346,共8页
To improve efficiency of search engines, the query result cache has drawn much attention re- cently. According to the query processing and user's query logs locality, a new hybrid result cache strategy which associat... To improve efficiency of search engines, the query result cache has drawn much attention re- cently. 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 accord- ance 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 hy- brid result cache is implemented in term of the document content and document ids (docIds) se- quence. Based on a score format and the new hybrid structure, an initial algorithm and a new rou- ting 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 signifi- cantly. By choosing comfortable combination of page cache and docIds cache, the new hybrid cac- hing strategy almost reduces more than 20% of the only cache and docId-only cache. average query time compared with the basic page- 展开更多
关键词 query result cache hybrid caching query repeated distance caching policy
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