关键词: 并行查询优化 两阶段优化 代价估计 启发式规则

Abstract:

The key problem is how to prune the big search space in order to get an optimized query plan for query parallel optimization.Therefore,based on the sh ared-nothing structure and taking communications into account with cost estimation,a two-phase optimization strategy is used to optimize the query tree  sequentially in the first phase and to parallelize the sequential optimization tree in the second phase by heuristic rules in the PRTDBASE optimizer.Mul  ti-processor parallelism is utilized and faster response time is obtained.

Key words: （parallel query optimization,two-phase optimization,cost estimation,heuristic rule）