Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> show parameter undo

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      AUTO
undo_retention                       integer     50000
undo_tablespace                      string      UNDO_NEW0




SQL> select RETENTION from dba_tablespaces where TABLESPACE_NAME='UNDO_NEW0';

RETENTION
-----------
NOGUARANTEE




SQL> select sum(bytes)/1024/1024/1024  "size_in_gb" from dba_data_files where tablespace_name='UNDO_NEW0';

size_in_gb
----------
95.9999542




SQL>   select u.maxquerysqlid,
  2           round (((max (u.unexpiredblks) * p.value) / 1024 / 1024 / 1024), 2)    as gb_unexpire
  3      from dba_hist_undostat u, v$parameter p
  4     where 1 = 1 and p.name = 'db_block_size' and u.end_time >= sysdate - 7
  5  group by u.maxquerysqlid, p.value
  6    having round (((max (u.unexpiredblks) * p.value) / 1024 / 1024 / 1024), 2) >= 95
  7  order by round (((max (u.unexpiredblks) * p.value) / 1024 / 1024 / 1024), 2) desc;


MAXQUERYSQLID GB_UNEXPIRE
------------- -----------
cj2h00pd9h4uf          96
0rc4km05kgzb9          96
bcczhd6zmr29y          96
0hf365k4cf8dm       95.99
c3grdz4gpkyp2       95.99
93bq2869k9k42       95.99
8tmj8s99y09zm       95.99
424h0nf7bhqzd       95.99
5xbbf036g054c       95.99
ajb6c0shjbb5v       95.97
3wyz3c99jnm6q       95.93
9dzjush42kmfs       95.86
19jayuy078n04       95.79
0422fz4tpgvvj       95.66
8f1sjvfxuup9w       95.62




SQL>   SELECT tablespace_name                                 tablespace,
  2           status,
  3           ROUND (SUM (bytes) / 1024 / 1024 / 1024, 2)     sum_in_gb,
  4           COUNT (*)                                       counts
  5      FROM dba_undo_extents
  6  GROUP BY tablespace_name, status
  7  ORDER BY 1, 2;

TABLESPACE                     STATUS     SUM_IN_GB     COUNTS
------------------------------ --------- ---------- ----------
UNDO_NEW0                      ACTIVE             0          1
UNDO_NEW0                      EXPIRED          .01          8
UNDO_NEW0                      UNEXPIRED      95.99      25312




SQL> SELECT ses.sid,
  2         ses.username,
  3         ses.status,
  4         ses.program     command,
  5         round(tra.used_ublk / 8192 / 1024 ,1 ) as MB
  6    FROM v$SESSION ses INNER JOIN v$TRANSACTION tra ON ses.saddr = tra.ses_addr;

no rows selected