Data Warehouse Maintenance over Dynamic Distributed Information Sources

随着数字信息库如雨后春笋般随处可见，世界各地计算机之间的互联性正在建立，在这种分布式数据源上构建和维护数据仓库（视图）已被认为对现代应用程序非常重要。但是，数据源不仅通过修改其内容，还通过修改其查询功能和模式以及加入或离开环境而不断发展。该研究解决了如何与数据源的模式变化同步重写视图定义这一关键而及时的问题，称为“视图同步”问题。可进化视图环境（Evolvable View Environment， EVE）解决方案基于用于视图进化的偏好模型和用于捕获数据源相互关系的元模型。设计了利用不同类型的元数据和视图演化偏好来同步视图的算法。建立了基于质量对替代观点重写进行排名的方法。为了确保在任何动态环境中的生存能力，采用了一种策略来协调模式更改时的视图同步和数据更改时更传统的视图维护。EVE软件系统的实现可作为概念验证和实验测试平台。进行实验评估，以评估重写的性能，适用性和质量。将该技术应用于Web和电子商务应用程序的案例研究有助于确定该技术的适用性和局限性。总而言之，该项目不仅将推进数据仓库（数据库技术的核心领域）的最新技术，而且通过提供技术和软件工具来简化对大型动态分布式数据源集的访问，其好处可能是深远的。http://davis.wpi.edu/dsrg/EVE

As digital repositories of information are springing up everywhere and interconnectivity between computers around the world is being established, the construction and maintenance of data warehouses (views) over such distributed data sources has been recognized to be of great importance for modern applications. However, data sources continuously evolve by modifying not only their content but also their query capabilities and schema and by joining or leaving the environment. This research addresses this critical and timely problem of how to rewrite view definitions synchronously with the schema changes of data sources, coined the "view synchronization" problem. The Evolvable View Environment (EVE) solution is based on a preference model for view evolution and a meta model for capturing data source interrelationships. Algorithms that exploit different types of metadata and view evolution preferences to synchronize views are designed. Measures for ranking alternative view rewritings based on their quality are established. To assure survivability in any dynamic environment, a strategy for coordinating view synchronization under schema changes and the more traditional view maintenance under data changes is incorporated. Implementation of the EVE software system serves as a proof of concept and as an experimental test bed. Experimental evaluations are conducted to assess performance, applicability, and quality of the rewritings. A case study on applying the technology to Web and E-commerce applications helps to determine the applicability as well as the limitation of the technology. In summary, this project will advance not only the state-of-the-art in data warehousing, a core area of database technology, but the benefits are potentially far-reaching by providing techniques and software tools for simplifying access to large sets of dynamic distributed data sources.http://davis.wpi.edu/dsrg/EVE