10g New Features- Tip of the Day

How to avoid or fix the famous ORA-01555 or "snapshot too old error"?

In 10g, use the RETENTION GUARANTEE (to avoid snapshot too old error ) clause when creating the undo tablespace (CREATE UNDO TABLESPACE or CREATE DATABASE) or later using the ALTER TABLESPACE statement.

SQL> alter tablespace undotbs1 retention guarantee;
Tablespace altered.

SQL> alter tablespace undotbs1 retention noguarantee;
Tablespace altered.