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* TROUBLESHOOTING: Possible Causes of Poor SQL Performance (Doc ID 33089.1)

Last updated on MARCH 12, 2021

Applies to:

Oracle Database - Enterprise Edition - Version 9.0.1.0 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 Backup Service - Version N/A and later
Information in this document applies to any platform.

Purpose

This document contains a number of potentially useful pointers for use when attempting to tune an individual SQL statement. This is a vast topic and this is just a drop in the ocean.

Troubleshooting Steps

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In this Document
Purpose
Troubleshooting Steps
 Diagnostics/Remedies
 1. Poorly tuned SQL
 2. Poor disk performance/disk contention
 3. Unnecessary sorting
 4. Late row elimination
 5. Over parsing
 6. Missing indexes/use of 'wrong' indexes
 7. Wrong plan or join order selected
 8. Import estimating statistics on tables
 9. Insufficiently high sample rate for CBO
 10. Skewed data
 11. New features forcing use of CBO
 12. ITL contention
References

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