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Don Burleson Blog 







ORA-01555 in expdp

Oracle Tips by Burleson Consulting

May 15, 2015

Question:  I have an export expdp job failing with an ORA-01555 error:

ORA-31693: Table data object "BAXXDB"."MS_DATA" failed to load/unload and is being skipped due to error:
ORA-02354: error in exporting/importing data
ORA-01555: snapshot too old: rollback segment number 20 with name "_SYSSMU20_4037596720$" too small

All of the other tables (before and after) exported fine, it is just this one table.   How do I fix this error in expdp?

Answer:  There are several solutions to this ORA-01555 problem.
  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. Increase the size of your undo_retention parameter.  Automatic undo management depends upon the undo_retention parameter, which defines how long Oracle should try to keep committed transactions in UNDO segments. However, the undo_retention parameter is only a suggestion.

  4. You must also have an UNDO tablespace that’s large enough to handle the amount of UNDO you will be generating/holding, or you will get "ORA-01555: Snapshot too old, rollback segment too small" errors.

  5. If a table has any columns defined a LOB? If so see MOSC Note: 452341.1.  You can offload CLOB tables using alternative techniques.

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