Evaluation of relational algebras incorporating the time dimension in databases
Evaluation of relational algebras incorporating the time dimension in databases
复制标题
评估数据库中包含时间维度的关系代数
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
R. Snodgrass
中科院分区：
文献类型：
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作者：
Edwin McKenzie;R. Snodgrass
关系代数是关系数据库的过程查询语言。在本文中，我们研究了关系代数的扩展，它可以查询记录时变数据的数据库。这样的代数是时态 DBMS 的关键部分。我们确定了 26 个标准，为评估时态代数提供了客观基础，其中 7 个标准被证明是相互不可满足的，这意味着不可能有完美的时态代数，选择满足哪些不相容的标准来描述现有代数的特征。总结了 12 个面向时间的代数，然后根据这些标准进行评估。我们证明，设计空间在某种意义上已经被探索过，因为基本设计决策的所有组合都至少有一个代表性代数。其余标准的覆盖范围提供了对每个代数质量的一种衡量标准。我们认为所有标准都是独立的，并且被确定为兼容的标准确实如此。最后，我们列出了其他人提出的看似合理的属性，这些属性要么被其他标准包含，要么没有明确定义，要么没有评估的客观基础。代数实现了许多不同的方法来完成最初看似简单的设计任务。
The relational algebra is a procedural query language for relational databases. In this paper we survey extensions of the relational algebra that can query databases recording time-varying data. Such an algebra is a critical part of a temporal DBMS. We identify 26 criteria that provide an objective basis for evaluating temporal algebras, Seven of the criteria are shown to be mutually unsatisfiable, implying there can be no perfect temporal algebra, Choices made as to which of the incompatible criteria are satisfied characterize existing algebras Twelve time-oriented algebras are summarized and then evaluated against the criteria. We demonstrate that the design space has in some sense been explored in that all combinations of basic design decisions have at least one representative algebra. Coverage of the remaining criteria provides one measure of the quality of each algebra We argue that all of the criteria are independent and that the criteria identified as compatible are indeed so, Finally, we list plausible properties proposed by others that are either subsumed by other criteria, are not well defined, or have no objective basis for being evaluated. The algebras realize many different approaches to what appears initially to be a straightforward design task.