公开(公告)号：US5717911A

公开(公告)日：1998-02-10

申请号：US377287

申请日：1995-01-23

申请人： Louise M. Madrid ,  Richard A. Meier ,  Franco Putzolu ,  Sunil Sharma ,  Thomas J. O'Shea ,  James H. Troisi ,  Hansjorg Zeller ,  Gary M. Gilbert ,  Donald S. Maier ,  Elizabeth G. Davis ,  Pedro Celis

发明人： Louise M. Madrid ,  Richard A. Meier ,  Franco Putzolu ,  Sunil Sharma ,  Thomas J. O'Shea ,  James H. Troisi ,  Hansjorg Zeller ,  Gary M. Gilbert ,  Donald S. Maier ,  Elizabeth G. Davis ,  Pedro Celis

IPC分类号： G06F12/00 ,  G06F17/30

CPC分类号： G06F17/30433 ,  Y10S707/99932 ,  Y10S707/99942

摘要： An SQL program executor and an SOL compiler both include options for avoiding recompilations of execution plans whenever the runtime object and the compile time object referenced by an execution plan meet predefined schema similarity criteria. Thus, recompilation is sometimes avoided even though the compile time object has been altered or the run time object is not the same object as the compile time object. To enable late binding, schema information is stored in each execution plan for each object to be accessed by the execution plan. The stored schema information is a subset of the full object schema, and includes information about all the aspects of the objects to be accessed which must remain unchanged in order for the execution plan to be operable. While executing a compiled program, the SQL executor avoids recompilations of execution plans whenever the runtime object and the compile time object referenced by an execution plan meet predefined schema similarity criteria. When a recompilation of an SQL program is required, only the execution plans which do not meet the schema similarity criteria are recompiled if the compiled program has been assigned appropriate runtime parameters. The late binding features of the SQL executor also enable a compiled program to access objects distinct from the objects referenced by the program at compile time. Similarly, the SQL compiler includes the ability to recompile only those execution plans which do not meet the schema similarity criteria and thus are inoperable.

摘要翻译： SQL程序执行器和SOL编译器都包括用于在运行时对象和执行计划引用的编译时对象满足预定义的模式相似性标准时避免重新编译执行计划的选项。 因此，即使编译时间对象已被更改或运行时间对象与编译时间对象不是相同的对象，有时也可避免重新编译。 为了启用后期绑定，模式信息存储在执行计划要访问的每个对象的每个执行计划中。 存储的模式信息是完整对象模式的一个子集，并且包括关于要访问的对象的所有方面的信息，这些信息必须保持不变，以便执行计划可操作。 在执行编译程序时，只要执行计划引用的运行时对象和编译时对象都符合预定义的模式相似性标准，SQL执行程序就会避免重新编译执行计划。 当需要重新编译SQL程序时，如果已编译的程序已分配适当的运行时参数，则仅重新编译不符合模式相似性标准的执行计划。 SQL执行程序的后期绑定功能还使得编译的程序能够在编译时访问与程序引用的对象不同的对象。 类似地，SQL编译器包括仅重新编译那些不符合模式相似性标准因而无法操作的执行计划的能力。