There are several steps you can take to purge safely and efficiently:
Back up the database before you start the purge process. For more information, see your Oracle server documentation.
Confirm the integrity of the database backup.
Create database rollback segments that are large, or set the commit size to a smaller number to ensure that the process does not terminate for lack of rollback segment space. See your database administrator for assistance. For more information about the commit size, see: Purge Project Data and PA: Commit Size for Archive and Purge, Oracle Projects Implementation Guide.
Run the purge process when the load on the system is relatively light.
The purge process can take several hours to complete, depending on the number of records to purge and the capacity of your system. You can purge many records more efficiently by submitting several smaller purges. On your first purge, set a Closed-Through Date (for closed projects) or Purge-Through (for open projects) that is far in the past, and gradually increase the date with each purge.