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How To Diagnose Why an Identical Query Has Different Plans (and Performance) in Different Environments (Doc ID 1671642.1)

Last updated on OCTOBER 30, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 8.0.6.0 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.

Purpose

This article discusses reasons that queries may have different execution plans in different environments . Many factors can influence an execution plan so that the same query running on the same database on same version and patchset level in 2 different environments may not have the identical plan. This document assists in diagnosing the possible reasons for the divergence.

Troubleshooting Steps

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In this Document
Purpose
Troubleshooting Steps
 Influential Factors in Plan Selection
 Statistics
 Base Object Statistics
 System Statistics
 Dynamic Statistics
 Statistics Feedback
 Physical Differences
 Physical and Logical Layout of the Database
 Schema Changes
 Settings and Features
 Parallelism
 Baselines, Profiles and Stored Outlines
 Bind Variables
 Optimizer and System Parameters
 SPFILE/PFILE
 PGA and SORT AREA
 Optimizer Parameters
 Client Settings
References

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