Monday, July 9, 2012

ORA-01555 causes and suggestions to avoid it

Here are the causesof this error
  • The undo segments are too small
  •  The application fetches across commits (a design flaw)
  • Delayed block cleanout
Here are some suggestions to avoid  ORA-01555: snapshot too old erro
  • Adjust the undo_retention parameter (for 9i and higher releases of Oracle
  •  Increase the size of the UNDO tablespace 
  • Increase the size of the undo segments [if using manual UNDO management]

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