CAJ | 학술논문

针对目前的查询优化技术并没有考虑网格环境中数据源的动态特征,导致数据访问质量很差的问题,文中提出了网格环境中具有服务质量(QoS)支持的数据访问方法.它能在查询优化的过程中考虑数据源的动态特征以及用户的QoS要求,根据用户的QoS要求选择不同的查询执行计划;文中还提出了基于管道并行方式的分层管道树来对多连接表达式进行优化,它不仅可以提高并行度而且可以尽快返回部分结果给用户.实验结果表明,文中提出的方法是有效的,可以为不同类型的用户提供不同等级的数据访问服务.
침대목전적사순우화기술병몰유고필망격배경중수거원적동태특정,도치수거방문질량흔차적문제,문중제출료망격배경중구유복무질량(QoS)지지적수거방문방법.타능재사순우화적과정중고필수거원적동태특정이급용호적QoS요구,근거용호적QoS요구선택불동적사순집행계화;문중환제출료기우관도병행방식적분층관도수래대다련접표체식진행우화,타불부가이제고병행도이차가이진쾌반회부분결과급용호.실험결과표명,문중제출적방법시유효적,가이위불동류형적용호제공불동등급적수거방문복무.
The data access on grid is of low quality because the existing query optimization techniques do not consider the dynamic properties of data resources in grid environments. In order to solve this problem, a QoS (Quality of Service)-based approach to data access is proposed, which considers not only the dynamic properties of data resources but also the QoS goals of users, and selects generated query plans according to the QoS goals of users. Moreover, a segmented pipe tree based on the pipelined parallelism is presented to optimize multi-join queries, which not only improves the parallelism but also returns some results to users as soon as possible. Experimental results show that the proposed approach is effective in providing data access at different levels for different users.