发明申请
- 专利标题: Method and apparatus for associating logical conditions with the re-use of a database query execution strategy
- 专利标题(中): 将逻辑条件与数据库查询执行策略的重用相关联的方法和装置
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申请号: US11094655申请日: 2005-03-30
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公开(公告)号: US20060224561A1公开(公告)日: 2006-10-05
- 发明人: Robert Bestgen , Carol Ramler , Jeffrey Tenner
- 申请人: Robert Bestgen , Carol Ramler , Jeffrey Tenner
- 申请人地址: US NY Armonk
- 专利权人: International Business Machines Corporation
- 当前专利权人: International Business Machines Corporation
- 当前专利权人地址: US NY Armonk
- 主分类号: G06F17/30
- IPC分类号: G06F17/30
摘要:
A query facility for database queries saves and re-uses query execution strategies, and automatically determines whether a strategy can be re-used when an imported variable changes. The query facility automatically saves one or more logical conditions associated with the one or more imported variables in the query. When the query is reused, the logical conditions are evaluated using the imported variable values, and the previously saved execution strategy is used only if the condition or conditions are met. Preferably, the logical conditions express a range of imported variable values which are included in a database subset data structure used by the saved query execution strategy, such as a materialized query table or partitioned table. Logical conditions are preferably generated by negating the predicates from a logical expression defining the applicability of the execution strategy, inserting the negated predicates into the query, and performing a transitive closure.