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。
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 cost.
出处
《电子设计工程》
2009年第8期110-112,共3页
Electronic Design Engineering
关键词
关系代数
查询优化
查询计划
优化策略
relational algebra
query optimization
query plan
optimization strategy
