MOBILE AGENT COOPERATION METHODS IN HYBRID QUERY OPTIMIZATION

The database field has developed very powerful technologies for finding efficient execution plans for declaratively specified queries. Moreover, database queries have increasingly complex in the age of the distributed DBMS (DDBMS). In order to optimize queries accurately, sufficient information must be available to determine which data access techniques are most effective. The role of query optimization is to find a strategy close to optimal. To optimize the query efficiently, it is important to choose the site to execute. For site selection, the statistical information of underlining relations is essential. In this paper, we propose the query optimization model based on mobile agents. This model provides a strategy for executing each query over the network in the most cost-effective way. Our proposed system focuses on these modules: query decomposition: decomposes the input query into mono-relation query using the detachment techniques, optimization plan: computes all possible plans using statistical database information and intermediate relation size by cooperating with mobile agents and chooses the optimized plan, and execution plan: executes the optimized plan by using mobile agent and send results to client