Changing the Datafiles for an Undo Tablespace to a Fixed Size

You change the datafiles for an undo tablespace to a fixed size to prevent the tablespace from growing too large or to better support Oracle Flashback operations. You can use Oracle Enterprise Manager Database Express (EM Express) to change the datafiles for an undo tablespace to a fixed size.

To change the datafiles for an undo tablespace to a fixed size:

  1. In EM Express, go to the Undo Management Details page, as described in "Viewing Undo Information".

  2. After determining the minimum required undo tablespace size, click the link after the Name field in the Tablespace section.

    The Tablespace page appears, with the undo tablespace displayed.

  3. Select and expand the undo tablespace. Select one of the datafiles for the undo tablespace. Then from the Actions menu, select Resize.

    The Resize Datafile page appears.

  4. In the Size field, enter the computed minimum size for the undo tablespace.

    See "Computing the Minimum Undo Tablespace Size Using the Undo Advisor".

  5. Click OK.

    A confirmation message appears.

  6. You can perform these steps for all the datafiles for the undo tablespace to change them all to a fixed size.