数据仓库视图一致性维护与下查研究

The Consistency of View Maintenance and Drill-down in a Warehous ing Environment

数据仓库是存储供查询和决策分析用的集成化信息仓库。实体化视图作为数据仓库中存储的主要信息实体,是由对上一级或外部数据源进行抽取、转化、传输和上载的数据构成的。当源数据发生变化时,如何进行数据仓库实体化视图的一致性维护以及OLAP查询,是一个有着实际意义的研究课题。论文提出的算法Glide采用版本控制、补偿思想和应答机制来协调源数据库与数据仓库间的数据更新,保证了数据仓库视图维护与下查的一致性,提高了算法的健壮程度和对源数据库端CPU的利用率,是以往同类算法的一个本质改进。论文指出算法Glide是完全一致的,并给出了严格的数学证明。文章还通过一个示例说明了该算法在实际中的具体运用。

A warehouse is a data repository containing integrated information for efficient querying and analysis.As the primary information entity stored in the data warehouse,the data of Materialized views is extracted,transformed,transmit-ted,or loaded from last or remote sources.Since a warehouse effectively implements materialized views ,we must maintain the views as data sources are updated.Using version control and compensating mechanisms ,along with acknowledgement mechanisms ,we introduce a new algorithm,Glide,to synchronize the data refreshments between data sources and data warehouse so as to ensure the consistency of maintenance and drill-down query.Several results are improved,and the robustness of the algorithm or the utilization ratio of CPU in source computers achieves a high performance.In addition,proofness is given that the level of consistency in algorithm Glide is complete.At the end of the paper,the authors il-lustrate the application of the algorithm by a typical example.