关键词: Mediator/Wrapper, 查询优化, 半连接, 半连接加权有向图, 固定终点最小分支流量算法

Abstract: This paper analyzes the integration system based on mediator/wrapper and its feature of query in detail. According to the fact that global join query involving more than several datasources is the main query type and its cost of query is very high, we considers global join query as the main object to be optimized. At the same time this article puts forward optimization of join query based on semijoin. This paper presents the directed weighted graph of semijoin in order to optimize semijoin execution plan. Furthermore, the fast and effective optimization algorithm is presented in order to produce optimum semijoin execution plan based on directed weighted graph of semijoin.

Key words: Mediator/Wrapper, Query optimization, Semijoin, Directed weighted graph of semijoin, Algorithm for minimal branch flow to fixed end-point