Saturday , September 23 2023

How To Check Undo Tablespace Usage in Oracle

Undo tablespace is extremely used during peak times. There is a possibility that some operations may be interrupted if you go uncontrolled. You should regularly check the undo tablespace usage.

Check Undo Tablespace Usage

You can use the following query to check the undo tablespace usage.

The information in the status column in the above query also indicates whether the corresponding undo information will be truncated. If its status is ACTIVE, this means that undo is being used in an active process and will not be truncated in any way. If its status is UNEXPIRED, this undo information belongs to a completed transaction, indicating that it has not yet exceeded the time specified by undo_retention. It can be truncated if required. If the status is EXPIRED, this undo information belongs to a completed transaction and indicates that it has exceeded the period specified by undo_retention. This means that this is the first undo information to be truncated. You can use the following query to control user-based undo usage.

You can ask users who consume a lot of undo to commit or rollback more frequently in their transactions. In this way, there will be no active use of undo for a long time.


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  1. Hi, can yo please update the second script? I just copied it and it’s missing something in the “FROM” segment

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