Question

ORA-01555 Snapshot Too Old

Answer 1

Caused by Read consistency Mechanism.

 

ORA-01555: snapshot too old: rollback segment number string with name "string" too small

Cause: Rollback records needed by a reader for consistent read are overwritten by other writers.

Action: If in Automatic Undo Management mode, increase the setting of UNDO_RETENTION. Otherwise, use larger rollback segments.

 

The ORA-01555 snapshot too old error can be addressed by several remedies:

1.  Re-schedule long-running queries when the system has less DML load.

2. Increasing the size of your rollback segment (undo) size.  The ORA-01555 snapshot too old also relates to your setting for automatic undo retention.

3. Don't fetch between commits.

   The ORA-01555 snapshot too old error can be addressed by several remedies:

4.  Re-schedule long-running queries when the system has less DML load.

5. Increasing the size of your rollback segment (undo) size.  The ORA-01555 snapshot too old also relates to your setting for automatic undo retention.

6. Don't fetch between commits.