RIA: Evaluation of Approximate Query Processing for Real- Time Databases

实时系统对数据库查询的处理有特定的时间限制，对其时态数据也有一致性要求。如果不可能在指定的截止日期之前生成数据库查询的精确答案，则可以使用近似查询处理来在时间限制内提供近似答案，但它不处理数据的时间维度。本项目整合了近似查询处理和时态数据两个领域，以检验实时数据库的近似查询处理的性能。对近似查询处理的语义支持所需开销的分析决定了近似查询处理系统的设计。性能分析演示了系统如何满足查询的时间约束，并在其近似答案中维护数据的时间一致性要求。该项目的结果提供了一个近似的查询处理系统，适用于必须保持数据一致性和必须满足截止日期的实时环境。

A real-time system has specific time constraints for the processing of database query as well as consistency requirements for its temporal data. If it is not possible to produce an exact answer to a database query by a specified deadline, approximate query processing can be used to provide an approximate answer within the time constraints, but it does not address the temporal dimension of the data. This project integrates the two areas of approximate query processing and temporal data in order to examine the performance of approximate query processing for a real-time database. An analysis of the overhead required for the semantic support of approximate query processing determines the design of the approximate query processing system. A performance analysis demonstrates how well the system satisfies the timing constraints of the queries and maintains the temporal consistency requirements of the data in its approximate answers. The result of this project provides an approximate query processing system that is applicable in real-time environments where data consistency must be maintained an deadlines must be met.