III: Medium: Data Interoperability via Schema Mappings

该奖项是根据2009年《美国复苏和再投资法案》(Public Law 111-5)资助的。异类数据的互操作性是每个关注数据分析、数据迁移和数据演变的现代企业面临的关键问题。数据互操作性的基本目标是促进从驻留在不同位置的多个异类数据源提取信息，并使其对最终用户透明。实现数据互操作性的核心是模式映射的设计和管理。模式映射是两个数据库模式之间关系的规范。模式映射是指定如何将不同来源的数据集成到统一格式或交换(即转换)为不同格式的基本构件。该项目的智力优势是为设计、理解和管理模式映射开发了坚实的基础和一套技术和工具。早期关于模式映射的基础性工作主要集中在操作模式映射的一些基本操作符的语义和算法问题上，重点是复合操作符和逆操作符。虽然到目前为止，人们已经很好地理解了复合算子，但对逆算子的研究还需要做更多的工作。这个项目的主要目标之一是深入研究逆算子和差分算子，这在很大程度上到目前为止还没有被探索。这个项目解决了逆运算符和差运算符的几个基本问题，包括以下问题：这两个运算符的正确语义是什么？表示这些运算符的确切语言是什么？有没有有效的算法来计算逆算子和差分算子的结果？该项目的一个并行目标是开发一套概念和技术，用于优化模式映射并将更复杂的模式映射转换为更简单但等价的模式映射。本项目的最后一个主要目标是研究使用数据示例来解释和说明模式映射的问题。众所周知，在两个模式之间设计模式映射是实现数据互操作性的最昂贵和最耗时的任务之一。以前的研究表明，(熟悉的)数据示例可以在设计模式映射方面提供非常强大的帮助。这个项目解决了以下问题：什么是模式映射的一个或多个说明性数据示例的正确概念？计算用于说明模式映射的小示例是容易还是困难？如何用数据示例说明大型而复杂的模式映射网络？如何描述多个模式映射之间的异同？该项目更广泛的影响是通过对研究生和本科生的教学、指导和研究培训，开发科学和工程领域的人力资源，促进该项目的基础和系统开发工作。有关通过该项目开发的出版物、课程材料、软件原型和工具的更多信息，请访问项目网页http://datainterop.cs.ucsc.edu

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Interoperability of heterogeneous data is a critical problem faced by every modern enterprise that is concerned with data analysis, data migration, and data evolution. The fundamental goal in data interoperability is to facilitate and make transparent to end-users the extraction of information from multiple heterogeneous data sources that reside in different locations. At the heart of achieving data interoperability is the design and management of schema mappings. A schema mapping is a specification of the relationship between two database schemas. Schema mappings are the essential building blocks in specifying how data from different sources are to be integrated into a unified format or exchanged (i.e., translated) into a different format.The intellectual merit of this project is the development of a solid foundation and a suite of techniques and tools for designing, understanding, and managing schema mappings. Earlier foundational work on schema mappings has mainly focused on the semantics and algorithmic issues of some of the basic operators for manipulating schema mappings with emphasis on the composition operator and the inverse operator. While the composition operator is well understood by now, much more remains to be done in the study of the inverse operator. One of the main goals of this project is to investigate in depth the inverse operator and also the difference operator, which remains largely unexplored to date. This project addresses several fundamental questions for the inverse and the difference operators, including the following: What is the right semantics for these two operators? What is the exact language for expressing these operators? Are there efficient algorithms for computing the result of the inverse operator and the difference operator? A parallel goal of this project is the development of a set of concepts and techniques for optimizing schema mapping and transforming more complex schema mappings into simpler, yet equivalent, ones. The final main goal of this project is to study the problem of using data examples to explain and illustrate schema mappings. The design of schema mappings between two schemas has been known to be one of the most costly and time-consuming tasks in achieving data interoperability. Prior studies have suggested that (familiar) data examples can be extremely powerful aids in designing schema mappings. This project addresses the following questions: What is the right notion or notions of illustrative data examples for schema mappings? How easy or difficult it is to compute small examples for illustrating schema mappings? How can one illustrate large and complex networks of schema mappings with data examples? How can one depict the similarities and differences among multiple schema mappings?The broader impact of this project is the development of human resources in science and engineering through the teaching, mentoring, and research training of graduate and undergraduate students on the foundational and system development work of this project. Further information about publications, course material, and software prototypes and tools developed through this project can be found at the project web page http://datainterop.cs.ucsc.edu