Invention Grant
US07987200B2 Method and apparatus for predicting selectivity of database query join conditions using hypothetical query predicates having skewed value constants
有权
使用具有偏差值常数的假设查询谓词来预测数据库查询连接条件的选择性的方法和装置
- Patent Title: Method and apparatus for predicting selectivity of database query join conditions using hypothetical query predicates having skewed value constants
- Patent Title (中): 使用具有偏差值常数的假设查询谓词来预测数据库查询连接条件的选择性的方法和装置
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Application No.: US11931255Application Date: 2007-10-31
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Publication No.: US07987200B2Publication Date: 2011-07-26
- Inventor: Michael S. Faunce , Shantan Kethireddy , Brian Robert Muras
- Applicant: Michael S. Faunce , Shantan Kethireddy , Brian Robert Muras
- Applicant Address: US NY Armonk
- Assignee: International Business Machines Corporation
- Current Assignee: International Business Machines Corporation
- Current Assignee Address: US NY Armonk
- Agent Roy W. Truelson
- Main IPC: G06F7/00
- IPC: G06F7/00
Abstract:
A database management system predicts a selectivity for database query conditions requiring a join of records from different tables. The system identifies at least one skewed value in a field specified in the join condition, and constructs, for each skewed value, a set of hypothetical query predicates in which the field specified in the join condition is replaced with a constant equal to the skewed value. The system then predicts the selectivity for the hypothetical predicates, using any appropriate prediction technique. The selectivities of the hypothetical predicates are used to predict a selectivity for the original query.
Public/Granted literature
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