[oracle@einyboy ~]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.1.0 - Production on Wed Jul 25 12:21:02 2012
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string AUTO
undo_retention integer 900
undo_tablespace string UNDOTBS1
SQL> alter system set undo_retention=1200 scope=both;
System altered.
SQL> show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string AUTO
undo_retention integer 1200
undo_tablespace string UNDOTBS1
SQL>