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11. 发明授权

US5857182A Database management system, method and program for supporting the mutation of a composite object without read/write and write/write conflicts 失效
标题翻译：数据库管理系统，支持复制对象突变的方法和程序，无需读/写和写/写冲突
公开(公告)号：US5857182A
公开(公告)日：1999-01-05
申请号：US786605
申请日：1997-01-21
申请人： Linda Gail DeMichiel , Gene Y. C. Fuh , Michelle Mei-Chiou Jou , Bruce Gilbert Lindsay , Nelson Mendonca Mattos , Serge Philippe Rielau , Brian Thinh-Vinh Tran
发明人： Linda Gail DeMichiel , Gene Y. C. Fuh , Michelle Mei-Chiou Jou , Bruce Gilbert Lindsay , Nelson Mendonca Mattos , Serge Philippe Rielau , Brian Thinh-Vinh Tran
IPC分类号： G06F17/30
CPC分类号： G06F17/30607 , Y10S707/99931 , Y10S707/99932 , Y10S707/99933 , Y10S707/99934 , Y10S707/99935 , Y10S707/99936 , Y10S707/99937 , Y10S707/99938
摘要： The system, method, and program of this invention avoids potential write/write conflicts and read/write conflicts when a subcomponent of a composite object (e.g., an ADT) is mutated. The embodiments of this invention define a copy semantic for the mutation function. In one embodiment, a copy function is inserted prior to any mutation function. In a another embodiment, a global compile-time analysis is performed to determine if a write/write or read/write conflict exists; and to eliminate redundant copy constructors if a conflict does exist. In a preferred embodiment, only a local analysis is performed during the parsing phase, thereby avoiding a global compile-time analysis. A mutation safe flag is associated with each parse tree node. A read target leaf parse tree node is set to false while non-leaf parse tree nodes (functions) derive their value from an incoming node, except that constructors and copy constructor functions are always true. Whether or not a copy is made of the composite object (i.e., whether or not a copy constructor is inserted) prior to a mutation is determined according to the setting of the mutation safe flags and according to the following. If a mutation safe flag for a mutation function is false, a copy constructor is inserted for the mutated composite object and the mutation safe flag is set to true. In addition, for update and trigger statements, the mutation safe flag for a mutated target is defaulted to true. Furthermore, related update entries are grouped together and a copy is generated for the common target. The generated copy is used as the common target for all of the mutations caused by the update entries grouped together in order to accumulate all of the desired mutations in a same copy of the composite object.
摘要翻译：本发明的系统，方法和程序在复合对象（例如，ADT）的子组件被突变时避免潜在的写入/写入冲突和读/写冲突。本发明的实施例定义了突变功能的复制语义。在一个实施例中，在任何突变功能之前插入复制功能。在另一实施例中，执行全局编译时分析以确定是否存在写/写或读/写冲突; 并且如果存在冲突，则消除冗余的拷贝构造函数。在优选实施例中，在解析阶段仅执行局部分析，从而避免了全局编译时分析。突变安全标志与每个解析树节点相关联。读取目标叶解析树节点设置为false，而非叶解析树节点（函数）从传入节点导出其值，除了构造函数和复制构造函数始终为真。根据突变安全标志的设置，根据以下来确定复制对象（即，是否插入复制构造函数）之前的副本是否被复制。如果突变功能的突变安全标志为假，则为突变复合对象插入复制构造函数，并将突变安全标志设置为true。另外，对于更新和触发语句，突变目标的突变安全标志默认为true。此外，将相关的更新条目分组在一起，并为共同目标生成副本。生成的拷贝被用作由更新条目组合在一起引起的所有突变的共同目标，以便累积复合对象的相同副本中的所有期望的突变。

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