My Oracle Support Banner

Primary Note: High Undo Space Usage (Doc ID 1578639.1)

Last updated on NOVEMBER 21, 2022

Applies to:

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


This troubleshooting guide is to identify high undo usage and correct them. This also lists various known issues on high undo usage and their workarounds.

This also explains the method for Sizing Undo Tablespace appropriately.

Troubleshooting Steps

To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document
Troubleshooting Steps
 Sizing Undo Tablespace
Determining Space Requirement:
 Shrink Undo Datafiles
 Troubleshooting High Space Usage
 Case 1. Active transaction consuming space (Undo extents are marked Active)
 Case 2. High Space Usage by Committed transactions (Undo extents are marked Unexpired)
 Case 3: Lots of Expired blocks
 Known Issues
 Diagnostic Information Required While Raising a Service Request

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.