Relational languages for metadata integration
Relational languages for metadata integration
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用于元数据集成的关系语言
DOI：
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发表时间：
2005
期刊：
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通讯作者：
E. Robertson
中科院分区：
文献类型：
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作者：
C. M. Wyss;E. Robertson
在本文中，我们开发了一种用于元数据集成的关系代数，即联邦互操作关系代数（Federated Interoperable Relational Algebra，FIRA）。FIRA具有许多理想的属性，如组合性，封闭性，确定性语义，适度的复杂性，支持嵌套查询，子代数等价于规范关系代数（RA），以及在某些类别的模式演化下的鲁棒性。除此之外，FIRA查询能够产生完全动态的输出模式，其中输出的关系的数量和/或关系中的列的数量随着输入实例而动态变化。在现有的关系元数据集成的查询语言中，只有FIRA提供了广义的动态输出模式，其中任何（固定）数量的输入列中的值可以确定输出schema.Further贡献本文包括元数据集成的扩展关系模型，联邦关系数据模型，这是严格向下兼容的关系模型的发展。此外，我们定义了关系查询语言的转换完整性的概念，并假设FIRA作为一个规范的转换完整的语言。我们还给出了一个声明式的，SQL一样的查询语言，相当于FIRA，称为联邦互操作结构化查询语言（FISQL）。虽然我们的主要贡献是概念，联邦模型，FISQL/FIRA，和概念的转换完整性，但有重要的应用数据集成和OLAP。除了总结这些应用程序，我们说明了使用FIRA优化FISQL查询使用基于规则的转换，直接平行的规范关系。最后，我们的文章与相关工作的扩展讨论，以及当前和未来的工作FISQL/FIRA的指示。
In this article, we develop a relational algebra for metadata integration, Federated Interoperable Relational Algebra (FIRA). FIRA has many desirable properties such as compositionality, closure, a deterministic semantics, a modest complexity, support for nested queries, a subalgebra equivalent to canonical Relational Algebra (RA), and robustness under certain classes of schema evolution. Beyond this, FIRA queries are capable of producing fully dynamic output schemas, where the number of relations and/or the number of columns in relations of the output varies dynamically with the input instance. Among existing query languages for relational metadata integration, only FIRA provides generalized dynamic output schemas, where the values in any (fixed) number of input columns can determine output schemas.Further contributions of this article include development of an extended relational model for metadata integration, the Federated Relational Data Model, which is strictly downward compatible with the relational model. Additionally, we define the notion of Transformational Completeness for relational query languages and postulate FIRA as a canonical transformationally complete language. We also give a declarative, SQL-like query language that is equivalent to FIRA, called Federated Interoperable Structured Query Language (FISQL).While our main contributions are conceptual, the federated model, FISQL/FIRA, and the notion of transformational completeness nevertheless have important applications to data integration and OLAP. In addition to summarizing these applications, we illustrate the use of FIRA to optimize FISQL queries using rule-based transformations that directly parallel their canonical relational counterparts. We conclude the article with an extended discussion of related work as well as an indication of current and future work on FISQL/FIRA.