How to Switch/Recreate Undo Tablespace at PDB Level(12cR2)

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Hi Dears,

In this article, we will see How to Switch/Recreate Undo Tablespace at PDB Level(12cR2)

In Oracle Database 12c Release 1 all containers in an instance shared the same undo tablespace.
In Oracle 12c Release 2 each container in an instance can use its own undo tablespace.
This new undo management mechanism is called local undo mode, Local undo mode is the default mode in newly created databases
You will probably only need to consider switching undo modes for upgraded instances.

Local undo mode:
In this mode, each PDB in container will have their own active undo tablespace

Share Undo mode:
In this mode, Every PDB will use only one undo tablespace for the entire instance.

Check local undo in database


When a CDB is in local undo mode, you can change it to use shared undo mode by issuing an ALTER DATABASE LOCAL UNDO OFF statement and restarting the database.

After converting to shared mode we have to drop undo tablespaces manually, by connecting to the respective database.


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Note: Please test scripts in Non Prod before trying in Production.
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