基于Petri网的查询计划模型适应性进化的一致性保证

CONSISTENCY OF ADAPTIVE EVOLUTION OF QUERY PLAN BASED ON PETRI NET

网格数据库是数据库技术和网格技术相结合后的新的研究领域,其适应性查询优化技术对传统的查询计划模型产生了新的要求。在分析了基于DAG(directed acylicgraph)的查询计划模型不足的基础上,提出了基于Petri网的查询计划描述模型QPPN(Query Plan Petn Net)网,丰富了查询计划模型中子查询与节点之间数据关系的描述能力,并在OPPN网的基础上,给出了适应性进化的查询计划一致性分析及定理,保证了进化的正确性。

Grid Database is a new research area in Grid and Database. There is new requirement for Adaptive query plan in this area. This paper describes the deficiency of query plan based on DAG,propeses a new QPPN model based on Petri Net. It also enriches the descriptive ability of relation between QPPN and nodes. This paper gives consistency analysis and theorem of QPPN and ensures the correctness of query evolution.