We study consistent query answering in relational databases. We consider an expressive class of schema constraints that generalizes both tuple-generating dependencies and equality-generating dependencies. We establish the complexity of consistent query answering and repair checking under tuple-deletion semantics for different fragments of the above constraint language. In particular, we identify new subclasses of constraints in which the above problems are tractable or even first-order rewritable.
翻译:我们研究对相关数据库的一致答题。我们考虑一种表达式的典型制约,它既概括了产生图普尔依赖性,又概括了产生平等依赖性。我们根据图普尔删除语的语义,确定上述制约语言不同部分的一致答题和修理检查的复杂性。特别是,我们找出了上述问题可伸缩甚至可重写的新制约亚类。