Oracle Error ORA-03170: deadlocked on readable physical standby (undo segment string)

Oracle Error Message

ORA-03170: deadlocked on readable physical standby (undo segment string)

Reason for the Error

A new undo segment was added. A query can occasionally deadlock when issued around the time an undo segment is added and used immediately on the primary.

Solution

Retry the query. Avoid creating new undo segments when using standby as a regular part of operation.