1. SQL Performance Tuning team recommends using COUNT(1) instead COUNT(*) for SQL query performance optimization. Example: --Do not use: SELECT COUNT(*) FROM master; --Use: SELECT COUNT(1) FROM master; 2. Never compare NULL with NULL. Consider that NULL is not like an empty string or...
SQL Tuning Advisor: Overview SQL优化顾问:概述 Using the SQL Tuning Advisor • Use the SQL Tuning Advisor to analyze SQL statements and obtain performance recommendations. • Sources for SQL Tuning Advisor to analyze: –Top Activity: Analyzes the top SQL statements currently active –SQL Tuning ...
4. Click on a SQL Tuning button: 5. Now you will get SQL PERFORMANCE TUNING recommendations SQL Tuning in Quest Toad for Oracle The example below shows how you can tune SQL query in TOAD for Oracle database. In TOAD we will use SQL tuning tool “Explain Plan”. 1. First I created ...
SELECT /*RECENTSQL */SQL_ID,CHILD_NUMBER,HASH_VALUE,ADDRESS,EXECUTIONS,SQL_TEXT FROM V$SQL WHERE PARSING_USER_ID = (SELECT USER_ID FROM ALL_USERS WHERE USERNAME = 'ISS') AND COMMAND_TYPE IN (2,3,6,7,189) AND UPPER(SQL_TEXT) NOT LIKE UPPER('%RECENTSQL%'); ...
Oracle ACE authors with decades of experience building complex production systems for government, industry, and educational organizations present a hands-on approach to enabling optimal results from PL/SQL. Real-world examples and...Rosenblum Michael...
要查看执行慢的SQL,可以使用Oracle提供的性能监控工具,例如Oracle Enterprise Manager或SQL Developer。以下是使用SQL Developer的步骤: 打开SQL Developer,并连接到Oracle数据库。 在左侧的导航栏中,展开“Performance”节点。 点击“SQL Tuning Advisor”。 在“SQL Tuning Advisor”页面上,点击“Create Task”按钮。 在...
statistics_level 参数是oracle9.2开始引入的一个控制系统统计参数收集的一个开关.一共有三个:basic,typical,all.支持alter session,alter system 动态修改.如果要用statspack或者AWR收集系统性能统计数据.那么这个参数的值必须为typical或all.通常all是一个全面收集,包括 OS以及sql执行路径方面的一些统计信息,除非遇见非常...
种声明,如RULE,COST,CHOOSE,ALL_ROWS,FIRST_ROWS . 你当然也在SQL句 级或是会话(session)级对其进行覆盖. 为了使用基于成本的优化器(CBO, Cost-Based Optimizer) , 你必须经常 运行analyze 命令,以增加数据库中的对象统计信息(object statistics) 的准确性. ...
SQL> 检查视图列V$SQL.IS_REOPTIMIZABLE显示优化器已经探测到了不正确的势评估并把该语句标示为将被重新优化。 COLUMN sql_text FORMAT A50 COLUMN is_reoptimizable FORMAT A16 SELECT sql_text, is_reoptimizable FROM v$sql WHERE sql_text LIKE '%f_tab_pl%' ...
Oracle调整顾问,也称为Oracle SQL Tuning Advisor,是一个自动化的工具,用于分析和优化SQL语句和数据库配置。它通过分析数据库的执行计划、访问路径、索引和表统计信息等数据,为DBA提供有关如何改进SQL性能的建议。一、工作原理Oracle调整顾问的工作原理是基于Oracle的自动性能诊断和调优框架(Automatic Performance Diagnostic...