【摘要】 讨论了ORDBMS的一些新特性 ,ORDBMS应该支持用户自定义的数据类型和函数 ;存储机制能够支持复杂对象或大对象 ;其索引结构必须是类属的 ;它还必须支持数据和函数的继承 .讨论了这些特性对查询优化策略的影响 ,指出传统DBMS的优化策略将不能适应这些新特性 ,提出了基于成本的查询优化模型更多还原

【Abstract】 New characteristics of the ORDBMS are introduced, the ORDBMS should support the types of data and functions defined by users; complex objects and big objects can be stored under their mechanism of storage; the structure of index of the ORDBMS must be classified by classes; the ORDBMS must support the inheritance of data and functions. This paper discusses the effect of these characteristics on the optimization of query policy, points out that the traditional query policy should not be fit for these new characteristics and puts forward the model of query optimization based on cost.更多还原