摘要： 提出一种贪心算法，以最佳方式把查询中所有Web services调用排列到一管线化执行方案中，使所有Web services以最佳并列方式工作，减少整个查询过程的总运行时间，解决以选择-投影-连接方式查询多个Web services的查询优化问题。该优化方案适用于在Web services之间存在任意优先约束的情况。

关键词: Web服务, 查询优化, 管线化, 贪心算法, 瓶颈开销

Abstract: This paper proposes a greedy algorithm to arrange all Web service calls of a query into a pipelined execution plan that optimally exploits parallelism among Web services to minimize the query’s total running time. It solves the basic question: query optimization for select-project-join queries spanning multiple Web services. The optimization plan can be found in the presence of arbitrary precedence constraints among Web services.

Key words: Web services, query optimization, pipelined, greedy algorithm, bottleneck cost

中图分类号: 

• TP319