We have a database that is around 1 TB in size, and a daily export process is set to execute at 12 AM CST. However, it's failing with the following error.
ORA-02354: error in exporting/importing data
ORA-01555: snapshot too old: rollback segment number 10 with nam"_SYSSMU10_3196945471$" too small
In order to resolve this issue, set undo retention to a greater value as part of the fix. Also, pay attention to the undo tablespace's size; it should be adequate.
Change the undo retention value to the duration of the export. Don't forget to add at least 30 minutes more. Keep the undo retention set to at least 20:30 hours if export takes 20 hours. In most cases, it will fix the problem.
SQL> show parameter undo NAME TYPE VALUE ------------------------------------ ----------- --------------- undo_management string AUTO undo_retention integer 900 undo_tablespace string UNDOTBS1 SQL> ALTER SYSTEM SET UNDO_RETENTION = 1800 scope=both; System altered. SQL> show parameter undo NAME TYPE VALUE ------------------------------------ ----------- --------------- undo_management string AUTO undo_retention integer 1800 undo_tablespace string UNDOTBS1