Cost Based Optimizer - Common Misconceptions and Issues - 10g and Above
(Doc ID 754931.1)
Last updated on DECEMBER 14, 2020
Applies to:Oracle Database - Enterprise Edition - Version 10.1.0.2 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.
This short article is intended to dispel a few myths about the cost based optimizer (referred to as the CBO from here on) and to highlight common mistakes and problem areas.
For a detailed description of the CBO see <Document:10626.1> which defines in detail some of the terms used in the article.
Also refer to:
11g Release 1 (11.1)
Part Number B28274-02
Chapter 11 The Query Optimizer
10g Release 2 (10.2)
Part Number B14211-03
Chapter 13 The Query Optimizer
This article is designed to give a basic understanding of the CBO.
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