You may receive the above ORA-01555 error during a long-running Performance Analysis (PA) transaction
- small or inadequate rollback segments (rbs)
- other background process like export may use up available resources
- not enough undo retention
If increasing the rbs and temp tablespace does not help, do the following:
Increase the undo_retention initialization parameter. To determine the appropriate value please run:
select max(maxquerylen) from v$undostat;
and set the undo_retention parameter to the retrieved value. Please be careful when you are increasing the parameter, it's not recommended to keep this parameter too high.