Return
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Title
Error: "ORA-01555 (snapshot to old)" - caused by Performance Analysis (PA) or other background pr -
Description
You may receive the above ORA-01555 error during a long-running Performance Analysis (PA) transaction
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Cause
- small or inadequate rollback segments (rbs)
- other background process like export may use up available resources
- not enough undo retention -
Resolution
WORKAROUND:
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. -
Additional Information
There are some delete statements running on the monitored instance which may generate UNDO, this is normal. We purge advisory data every now and then so the data won't grow and cause performance issues on the monitored instance. Before we delete, it also being copied to the repository.