| 摘要: |
| 在面向对象数据库中，“联系-选择”复合操作的功能类似于嵌套关系数据库中多个嵌套关系的连接，是查询优化时需要重点考虑的问题．本文首先证明满足一定条件限制的“联系-选择”复合操作可在多项式时间内得到最佳查询方案，然后给出了支持双向联系时“联系-选择”复合操作的一些优化算法．模拟实验表明，文中所提出的优化算法性能平稳，效果很好． |
| 关键词: 面向对象数据库 查询优化 “联系-选择”复合操作 |
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| OPTIMIZATION OF "ASSOCIATE-SELECT" COMPOUND OPERATION IN OBJECT-ORIENTED; DATABASE SYSTEMS |
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WU Shengli,WANG Nengbin
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| Abstract: |
| “Associate-Select”compound operation．which is similar in functionality to join operation of multi-nested relations in nested relational databases，is a key issue of query optimization in object-oriented database systems．This paper proves that the optimum solution for treelike“Associate-Select”queries with some restrictions can be obtained with polynomial complexity，then presents some algorithms to deal with the situation when birelationship exists in complex objects(for example by defining inverse attribute et a1．)．A simulation experiment is performed to demonstrate the steadiness and effective ness of the algorithms proposed in the paper． |
| Key words: Object-oriented database query optimization " associate-select" compound operation |
