| 摘要 |
An object language application (e.g., C++, JAVA, etc.,) issues a query over a view and receives back, as query results, handles to application type objects which can be further manipulated by the application. A view is defined herein as a collection of a view type, and a view type is defined as a class or type. A tool is used by a programmer writing the application to create object language class definitions that are based upon the view type of the view referenced by the query. Upon receipt of the query referencing a view type, a query engine generates a query plan that builds mock (i.e., proxy) application type objects in memory based upon the view types. The application objects have a form that is consistent with the class definition for a type of object returned as a result. The application can run methods on the application type objects or point to other application type objects from the handles, to the application objects, that are returned to the application; and these manipulations will be understood by the query engine. In a preferred embodiment, query rewrite optimizations are applied to the queries over views requiring object building in order to optimize the evaluation of the query and the building of view objects as query results. Query rewrite optimizations can also be applied so that parts of the query are pushed down to the DBMS to minimize the number of objects that need to be built.
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