Data Warehouse Maintenance over Dynamic Distributed Information Sources

随着信息的数字存储库在各地如雨后春笋般涌现，并且世界各地的计算机之间的互连性正在建立，在这种分布式数据源上的数据仓库（视图）的构造和维护已经被认识到对于现代应用是非常重要的。然而，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通过加入或离开环境来不断发展。本文研究了如何在数据源模式改变的同时同步重写视图定义这一关键而及时的问题，即“视图同步”问题。可演化视图环境（Evolvable View Environment，EVE）解决方案基于用于视图演化的偏好模型和用于捕获数据源相互关系的Meta模型。算法，利用不同类型的元数据和视图进化的偏好同步视图的设计。建立了基于质量的替代观点重写排名方法。为了保证在任何动态环境中的生存性，一个战略，协调视图同步模式的变化和更传统的数据变化下的视图维护。EVE软件系统的实施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。最后通过一个应用于Web和电子商务应用的案例分析，说明了该技术的适用性和局限性。总之，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，而且通过提供简化对大量动态分布式数据集的访问的技术和软件工具，其好处可能是深远的。sources.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