| 关系代数与SQL查询优化的研究 |
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| 引用本文： | 王峥,王亚平. 关系代数与SQL查询优化的研究[J]. 国外电子元器件, 2009, 0(8): 110-112 |
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| 作者姓名： | 王峥 王亚平 |
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| 作者单位： | 郑州铁路职业技术学院;西安外事学院; |
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| 摘 要： | 详细分析关系代数表达式等价变换前后的查询代价。针对DBMS查询优化器如何生成成本最小的查询计划问题，给出关系代数表达式的优化规则。提出基于关系代数运算等价变换规则的SQL查询优化策略。该策略提供了查询优化器生成成本最小的查询计划的设计依据。
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| 关 键 词： | 关系代数 查询优化 查询计划 优化策略 |
Research on relational algebra and SQL query optimization |
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| WANG Zheng,WANG Ya-ping. Research on relational algebra and SQL query optimization[J]. International Electronic Elements, 2009, 0(8): 110-112 |
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| Authors: | WANG Zheng WANG Ya-ping |
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| Affiliation: | WANG Zheng, WANG Ya-pin(1.Zhengzhou Railway Vocational Technology College, Zhengzhou 450052,China; 2.Xi ＇ an International University, Xi ＇ an 710077,China ) |
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| Abstract: | In this paper,the query cost before and after the equivalent transformation of the relational algebra expression is researched and analyzed in detail.Aiming at how the DBMS query optimizer to generate the smallest cost query plan,optimization rules of the relational algebra expression are given.SQL query optimization strategy based on equivalent transformation rules of the relational algebra is proposed.The strategy provides the design basis for the query optimizer to generate query plan of the smallest cos... |
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| Keywords: | relational algebra query optimization query plan optimization strategy |
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