port deep tank

For the join operator that is the most difficult to process and optimize in DBMS,the query optimization strategies, based on genetic algorithms, over the plan collections of left-deep join tree and the plan collections of bushy join tree are discussed.

介绍基本遗传算法的基本思想和工作流程,针对数据库管理系统中最难处理和优化的连接操作,讨论在左深连接树的计划集合和浓密连接树的计划集合上的基于遗传算法的查询优化策略。