Скачать или смотреть Resolving the ORA-14452 Error: How to Drop a GTT in Oracle 12c

Learn how to identify blocking sessions and successfully drop a Global Temporary Table (GTT) in Oracle 12c without losing data.
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How to Drop a Global Temporary Table (GTT) in Oracle 12c: Troubleshooting the ORA-14452 Error

In the world of databases, encountering errors can be quite frustrating, especially when you’re not sure why they occur. A common issue faced by many Oracle 12c users is the inability to drop a Global Temporary Table (GTT), which can throw the error ORA-14452: attempt to create, alter or drop an index on a temporary table already in use. This post will walk you through understanding this error and provide a structured approach to resolving it easily.

What is a GTT?

A Global Temporary Table (GTT) is a special kind of table in Oracle that is used to store temporary data for the duration of a session or a transaction. It's useful for scenarios where you need to handle intermediate calculations or bulky datasets without affecting the underlying database structure permanently.

Understanding the Error

The error message ORA-14452 specifically indicates that there are still active sessions or transactions utilizing the temporary table you're trying to drop. Here’s a breakdown of what this means:

Active Sessions: There are sessions holding locks on the GTT. This could occur if a user has not completed their transaction or has maintained an open session.

Pending Transactions: If other transactions are still in progress and referencing the GTT, Oracle will prevent you from dropping the table.

Given this scenario, what do you do next? The key lies in identifying which sessions are blocking your GTT.

Steps to Identify Blocking Sessions

Run the Query: To find out which session is blocking the GTT, run the following SQL query:

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What This Does: The query checks the locks held on the GTT and identifies which username is associated with the blocking session.

Note the SID and SERIAL# : Once you have identified the session, take note of the SID and SERIAL# which will be necessary to terminate the session.

Correcting Blocking Sessions

Option 1: Gentle Approach

Before taking drastic actions, it’s advisable to politely ask the user holding the lock to close their session. This is essential in environments where data integrity is critical.

Option 2: Force Terminate the Session

If you absolutely must drop the GTT and cannot wait for the session to close, you can forcibly terminate the session with the following command:

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Caution: Use this command with caution as it may cause loss of any uncommitted data in the session being killed.

Final Cleanup

After terminating the blocking session, you should now be able to drop the GTT with the following command:

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If errors still persist after these steps, ensure no other active transactions are using the GTT or consider checking for additional locks.

Conclusion

Dropping a GTT in Oracle 12c while it's in use can certainly be challenging, but by identifying the blocking sessions and employing the right strategies, you can resolve the ORA-14452 error effectively. Remember to always try to communicate with users before opting to end their sessions for smoother database operations!

Feel free to leave your thoughts or questions in the comments below; we're here to help!