SQL> select systimestamp from dual;

SYSTIMESTAMP
--------------------------------------------------
25-JUL-12 09.18.04.683056 AM +01:00

SQL> insert into test1 (select * FROM DCA_CLA_BATCH AS OF TIMESTAMP TO_TIMESTAMP([b]'2012-07-23 13:15'[/b],'YYYY-MM-DD HH24:MI'));

1018 rows created.

SQL> rollback;

Rollback complete.

SQL> insert into test1 (select * FROM DCA_CLA_BATCH AS OF TIMESTAMP TO_TIMESTAMP([b]'2012-07-23 13:00'[/b],'YYYY-MM-DD HH24:MI'));
insert into test1 (select * FROM DCA_CLA_BATCH AS OF TIMESTAMP TO_TIMESTAMP('2012-07-23 13:00','YYYY-MM-DD HH24:MI'))
            *
ERROR at line 1:
ORA-01555: snapshot too old: rollback segment number 20 with name "_SYSSMU20$" too small

SQL> show parameter flash

NAME                                 TYPE                             VALUE
------------------------------------ -------------------------------- -----------------------
db_flashback_retention_target        integer                          1440
SQL> show parameter undo

NAME                                 TYPE                             VALUE
------------------------------------ -------------------------------- -----------------------
undo_management                      string                           AUTO
undo_retention                       integer                          900
undo_tablespace                      string                           UNDOTBS

ECSCDAS1S > alter system set undo_retention=0 scope=both sid='*';

System altered.

ECSCDAP1P > select     instance_name,name
  2  ,  floor(space_limit / 1024 / 1024) "Size MB"
  3  ,  ceil(space_used  / 1024 / 1024) "Used MB"
  4  from       v$recovery_file_dest,v$instance;

INSTANCE_N NAME               Size MB    Used MB
---------- --------------- ---------- ----------
CSCDAP1    +CCDA_FLASH_01      102400       9319

ORIGINAL_VALUE                           PARAMETER_NAME
---------------------------------------- -----------------------------
                                         db_flash_cache_file
0                                        db_flash_cache_size
+CCDA_FLASH_01                           db_recovery_file_dest
5344591872                               db_recovery_file_dest_size
1440                                     db_flashback_retention_target
900                                      undo_retention
on                                       recyclebin

CURRENT_VALUE                            PARAMETER_NAME
---------------------------------------- -----------------------------
                                         db_flash_cache_file
0                                        db_flash_cache_size
+CCDA_FLASH_01                           db_recovery_file_dest
107374182400                             db_recovery_file_dest_size
7200                                     db_flashback_retention_target
0                                        undo_retention
on                                       recyclebin

ECSESBP1 > select     instance_name,name
  2  ,  floor(space_limit / 1024 / 1024) "Size MB"
  3  ,  ceil(space_used  / 1024 / 1024) "Used MB"
  4  from       v$recovery_file_dest,v$instance
  5  order by name;

INSTANCE_N NAME               Size MB    Used MB
---------- --------------- ---------- ----------
CSESBP1    +NFL_CS_FLASH        30720      30650

ECSESBP1 > select value from v$parameter
  2  where name='db_flashback_retention_target';

VALUE
----------------
1440

Errors in file /u01/app/oracle/admin/CSESBP/udump/csesbp1_ora_26461.trc:
ORA-19815: WARNING: db_recovery_file_dest_size of 32212254720 bytes is 100.00% used, and has 0 remaining bytes available.
Thu Jul 26 01:32:59 2012
************************************************************************
You have following choices to free up space from flash recovery area:
1. Consider changing RMAN RETENTION POLICY. If you are using Data Guard,
   then consider changing RMAN ARCHIVELOG DELETION POLICY.
2. Back up files to tertiary device such as tape using RMAN
   BACKUP RECOVERY AREA command.
3. Add disk space and increase db_recovery_file_dest_size parameter to
   reflect the new space.
4. Delete unnecessary files using RMAN DELETE command. If an operating
   system command was used to delete files, then use RMAN CROSSCHECK and
   DELETE EXPIRED commands.