断接下查询的缓存处理  

Answering Query Through Cache During Disconnection

作　　者：吴婷婷[1] 章文嵩[1] 周兴铭[1] 

机构地区：[1]国防科学技术大学并行与分布处理国家重点实验室,长沙410073

出　　处：《计算机学报》2003年第10期1393-1399,共7页Chinese Journal of Computers

基　　金：国家自然科学基金 ( 60 2 73 0 68)资助

摘　　要：移动环境下 ,由于无线网络可靠性低、费用高 ,移动主机本身受电源、资源等方面的限制 ,移动主机经常会主动或被动地处于断接 ,即没有网络连接的状态 .为了提高断接时移动客户对数据的访问能力 ,有效利用移动缓存 ,该文提出断接下基于语义缓存的查询处理QPID算法 .该算法的主要思路是先找出缓存中与当前查询相关的缓存项 ,再通过对相关项数据的进一步处理获得缓存中满足查询的结果 .试验表明 ,基于QPID算法的查询处理可以更好地满足断接下客户的查询请求 .Because of the characteristic of wireless networks and mobile units in mobile environments, the mobile computer has to be disconnected often by the user or by accident. During disconnection, clients have no access to networks and can only access information in the local cache. In this paper, we propose a query processing algorithm QPID (Query Processing In Disconnection) based on semantic caches. Semantic cache is a cache that explores the semantic locality among client-issued queries and is composed of former query results and descriptions. In order to provide better support for clients to access data during disconnection and to utilize cache more effectively, QPID algorithm satisfies a query by several cache items. The main idea is to find cache items related to the query first, classify them into direct-related and indirect-related cache items, then process data corresponding to these cache items to get query result. Whether equivalent query answer is obtained is determined by the descriptions of cache items and the query. Experiments show that based on QPID algorithm, semantic cache can be used more effectively and more client queries can be answered during disconnection.

关 键 词：缓存处理 数据访问 数据集合 数据查询 待价查询 数据库 语义缓存 QPID算法 

分 类 号：TP331.13[自动化与计算机技术—计算机系统结构]