Research in Time-and-Error-Constrained Databases

可以将“时间受限数据库”定义为在(A)响应查询、(B)处理事务和(C)数据库维护方面具有严格的定时约束的数据库。“时间受限查询”的形式是“在不超过t个时间单位内获得信息x”。该项目研究在集中式和单用户时间受限数据库中处理任意时间受限查询的问题。研究了将查询修改为具有最多的“信息性”响应并且可以在给定的时间限制内以受控的超支风险进行评估的各种方法。介绍了碎片选择和风险分析的技术。研究了控制查询处理时间的语义查询处理技术。这项研究的预期结果是(I)处理有时间限制的查询的方法，(Ii)一个时间限制的数据库管理系统的原型和使用该原型的性能评估，以及(Iii)关于在不同数据特征下使用各种选项的启发式方法。研究成果的潜在应用领域是那些对时间要求严格的数据库处理非常重要的领域，例如科学应用和制造环境。

One may define a "time-constrained database" as a database that has strict timing constraints in (a) responding to queries, (b) processing transactions, and in (c) database maintenance. A "time-constrained query" has the form of "get the information x in no more than t time units". This project deals with the problem of processing arbitrary time-constrained queries in centralized and single-user time-constrained databases. Various ways of revising a query into one which has the most "informative" response and can be evaluated within the given time constraint with a controlled risk of overspending are investigated. Techniques for fragment selection and risk analysis are introduced. Semantic query processing techniques to control the query processing times are investigated. The expected outcome of this research is (i) a methodology to process queries with time constraints, (ii) a prototype time- constrained database management system and a performance evaluation using the prototype, and (iii) heuristics about the use of various options under different data characteristics. Potential applications of the research results are in those areas where time-critical database processing is important, e.g., scientific applications and manufacturing environments.