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Schema mapping coverage
Annals of Mathematics and Artificial Intelligence ( IF 1.2 ) Pub Date : 2021-01-02 , DOI: 10.1007/s10472-020-09720-4
Ning Deng , Jan Chomicki

In this paper, we introduce and study schema mapping coverage for relational databases. Given a relational schema mapping in the presence of both source dependencies and target dependencies, the coverage problem is to decide and describe which source instances have solutions under the mapping. Our main motivation is to describe limitations of schema mappings and hence to effectively determine if the mappings can fulfill their user expectations for the given tasks. We first propose using database dependencies to model user expectations of schema mappings. Then we formally define the notion of schema mapping coverage and propose using a set of dependencies in the source schema language to represent coverage. We look into how target dependencies indirectly enforce dependencies via mapping specifications on source instances and thus determine which source instances have solutions. We prove that the problem of computing schema mapping coverage is undecidable in general. We present algorithms for computing coverage for schema mappings where both the source dependencies and the target dependencies consist of functional dependencies and acyclic inclusion dependencies. Schema mapping coverage describes the ability to map source instances to target instances for mappings, it provides a way to describe limitations of schema mappings, which can be especially useful for mapping design and evolution.



中文翻译:

模式映射覆盖

在本文中,我们介绍和研究关系数据库的模式映射范围。给定在源依赖关系和目标依赖关系都存在的情况下的关系模式映射,覆盖范围的问题是确定并描述哪些源实例在映射下具有解决方案。我们的主要动机是描述架构映射的局限性,从而有效地确定映射是否可以满足用户对给定任务的期望。我们首先建议使用数据库依赖关系来建模用户对架构映射的期望。然后,我们正式定义模式映射覆盖率的概念,并提出使用源模式语言中的一组依赖关系来表示覆盖率。我们研究目标依赖关系如何通过在源实例上映射规范间接地强制依赖关系,从而确定哪些源实例具有解决方案。我们证明了计算模式映射覆盖率的问题通常是不确定的。我们提出了用于计算架构映射覆盖率的算法,其中源依赖项和目标依赖项均由功能依赖项和非循环包含依赖项组成。模式映射覆盖率描述了将源实例映射到目标实例以进行映射的能力,它提供了一种描述模式映射限制的方法,这对映射设计和演化特别有用。我们提出了用于计算架构映射覆盖率的算法,其中源依赖项和目标依赖项均由功能依赖项和非循环包含依赖项组成。模式映射覆盖率描述了将源实例映射到目标实例以进行映射的能力,它提供了一种描述模式映射限制的方法,这对映射设计和演化特别有用。我们提出了用于计算模式映射的覆盖率的算法,其中源依赖项和目标依赖项均由功能依赖项和非循环包含依赖项组成。模式映射覆盖率描述了将源实例映射到目标实例以进行映射的能力,它提供了一种描述模式映射限制的方法,这对映射设计和演化特别有用。

更新日期:2021-01-02
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