ORACLE中SQL执行原理及性能优化研究

SQL性能优化是一个系统工程,熟知SQL语法并不能保证SQL语句的高效。从分析ORACLE数据库中SQL语句执行原理入手,指出减少SQL语句的解析次数和优化CBO是SQL性能优化的重点,并用实例验证了使用绑定变量和高速缓存游标在提高SQL性能方面的重要作用。CBO将输入的SQL语句转化为实际的执行计划,而执行计划的优劣又主要依赖于初始化参数与统计信息的质量,因此在优化CBO中重点阐述了如何设置影响CBO行为的初始化参数及收集统计信息必须遵守的五条原则。

RESEARCH OF SQL'S EXECUTION-PRINCIPLE AND PERFORMANCE-TUNING IN ORACLE

SQL performance tuning is system engineering.Being familiar with SQL grammar can not guarantee the high efficiency of SQL statement.In this paper it analyzes the execution process of SQL statement in Oracle database and finds out that reducing times of SQL statement parsing and optimizing CBO are the emphases of SQL performance tuning.Then it validates the key role of using bound variable and cache cursor in enhancing performance of SQL with example.CBO transforms SQL statement into execution plan,the quali...