| 摘要: |
| 对线性序约束数据库中的数据依赖和无损连接分解进行了研究.介绍了线性序约束数据库的一些基本概念,提出了线性序约束关系中多区域存在依赖和分组多区域存在依赖的概念,证明了变量集满足变量独立和多区域存在依赖是进行模式无损连接分解的充要条件.探讨了变量集在坐标线性变换下保持良性分解的情形. |
| 关键词: 线性序约束数据库,无损连接分解,多区域存在依赖,变量独立,分组多区域存在依赖. |
| DOI： |
| 分类号: |
| 基金项目:本文研究得到国家自然科学基金资助. |
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| Lossless Join Decomposition in Dense Linear Order Constraint Databases |
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FAN Zhi-xin,SHI Bo-le
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| Abstract: |
| In this paper, the data dependencies and lossless join decomposition in dense linear order constraint databases are studied. Several concepts of the dense linear order constraint databases are introduced. The concept of the multi-region existence dependencies is defined and studied. It is proved that the lossless join decomposition of constraint relational scheme preserves if and only if they satisfies variable independence and multi-region existence dependencies. Another dependency——partitioned multi-region existence dependencies is given. The issue of variable set under linear transformation is also proposed. |
| Key words: Dense linear order constraint database, lossless join decomposition, multi-region existence dependencies, variable independence, partitioned multi-region existence dependencies. |
