.png){kind=icon}
返回
Data integration under integrity constraints
.png){kind=icon}
PRE
AI
DOI：10.1016/S0306-4379(03)00050-4.png)
.png){kind=icon}
原文求助.png){kind=icon}
分享.png){kind=icon}
收藏
摘要
En 中文
Data integration systems provide access to a set of heterogeneous, autonomous data sources through a so-called global schema. There are basically two approaches for designing a data integration system. In the global-as-view approach, one defines the elements of the global schema as views over the sources, whereas in the local-as-view approach, one characterizes the sources as views over the global schema. It is well known that processing queries in the latter approach is similar to query answering with incomplete information, and, therefore, is a complex task. On the other hand, it is a common opinion that query processing is much easier in the former approach. In this paper we show the surprising result that, when the global schema is expressed in the relational model with integrity constraints, even of simple types, the problem of incomplete information implicitly arises, making query processing difficult in the global-as-view approach as well. We then focus on global schemas with key and foreign key constraints, which represents a situation which is very common in practice, and we illustrate techniques for effectively answering queries posed to the data integration system in this case. (C) 2003 Elsevier Ltd. All rights reserved.
Keyword:
data integration
integrity constraints
global-as-view approach
query answering
AI总结
对已上传原文的论文进行重点信息的提取，主要内容包括：简要概述、研究摘要、背景介绍、关键亮点、图文解析、展望与总结。
期刊
IF:
3.9
论文数:
2.8K
被引数:
1.8K
机构
暂无机构信息
引用论文
.png){kind=icon}
Subject-Predicate Agreement in Hebrew: Interrelations with Semantic Processes希伯来语的主谓一致：与语义过程的相互关系
PREAI
分享收藏
查看更多内容