[bbk2228] 第41集 - Chapter 11-SQL Statement Tuning(00)

Objectives

After completing this lesson,you should be able to do the following:

Control optimizer options

Use optimizer hints

Employe plan stability

Use store outlines(在10g,11g已经过时)

Use SQL Trace and TKPROF

Overview

The purpose of this lesson is:

To provide mthods to determine the resources used by SQL statements:

-Oracle Enterprise Manager

-Statuspack

-Explain plan

-SQL Trace and TKPROF

-Autotrace

To determine which SQL statements possibly require tuning

Not to tune the actual SQL statements

Optimizer Modes

There are two types of optimizer modes:

Rule-based:(Rule based Optimizer 俗称RBO)

Uses a ranking system

Syntax-and data dictionary-driven(基于语法逻辑和一些数据字典信息进行驱动的优化)

Cost-based:(Cost based Optimizer 俗称CBO)

Chooses the path with lowest cost

Statistics-driven(基于分析统计报表数据，进行优化驱动)

备注：目前RBO已经退出历史舞台，不在实际应用中使用;