Undo tablespace usage

 Below are the undo tablespace usage sql queries

1.

select a.sid, a.serial#, a.username, b.used_urec used_undo_record, b.used_ublk used_undo_blocks
from v$session a, v$transaction b
where a.saddr=b.ses_addr ;

2.

select
s.sid,s.serial#,
NVL(s.username, 'NA') orauser,
s.program,r.name undoseg,
t.used_ublk * TO_NUMBER(x.value)/1024||'K' "Undo"
from
sys.v_$rollname r,
sys.v_$session s,
sys.v_$transaction t,
sys.v_$parameter x
where s.taddr = t.addr
AND r.usn = t.xidusn(+)
AND x.name = 'db_block_size';

3.

SET LINESIZE 200
COLUMN username FORMAT A15
SELECT s.username,
       s.sid,
       s.serial#,
       t.used_ublk,
       t.used_urec,
       rs.segment_name,
       r.rssize,
       r.status
FROM   v$transaction t,
       v$session s,
       v$rollstat r,
       dba_rollback_segs rs
WHERE  s.saddr = t.ses_addr
AND    t.xidusn = r.usn
AND    rs.segment_id = t.xidusn
ORDER BY t.used_ublk DESC;

4.

SELECT s.inst_id,
        r.name                   rbs,
        nvl(s.username, ‘None’)  oracle_user,
        s.osuser                 client_user,
        p.username               unix_user,
        to_char(s.sid)||’,’||to_char(s.serial#) as sid_serial,
        p.spid                   unix_pid,
        TO_CHAR(s.logon_time, ‘mm/dd/yy hh24:mi:ss’) as login_time,
        t.used_ublk * 8192  as undo_BYTES,
                st.sql_text as sql_text
   FROM gv$process     p,
        v$rollname     r,
        gv$session     s,
        gv$transaction t,
        gv$sqlarea     st
  WHERE p.inst_id=s.inst_id
    AND p.inst_id=t.inst_id
    AND s.inst_id=st.inst_id
    AND s.taddr = t.addr
    AND s.paddr = p.addr(+)
    AND r.usn   = t.xidusn(+)
    AND s.sql_address = st.address
  AND t.used_ublk * 8192 > 1073741824
  ORDER
       BY undo_BYTES desc
/

5.
select s.sid, t.name, s.value
from v$sesstat s, v$statname t
where s.statistic#=t.statistic#
and t.name='undo change vector size'
order by s.value desc;

6.
select sql.sql_text, t.used_urec records, t.used_ublk blocks,
(t.used_ublk*8192/1024) kb from v$transaction t,
v$session s, v$sql sql
where t.addr=s.taddr
and s.sql_id = sql.sql_id
and s.username ='&USERNAME';

7.
select SID,PROGRAM from v$session where TYPE='BACKGROUND';

8.
col machine for a10;
select  s.sid,s.serial#,username,s.machine,
t.used_ublk ,t.used_urec,(rs.rssize)/1024/1024 MB,rn.name
from    v$transaction t,v$session s,v$rollstat rs, v$rollname rn
where   t.addr=s.taddr and rs.usn=rn.usn and rs.usn=t.xidusn and rs.xacts>0;