Uso da PGA por sessões

SELECT SS.USERNAME,
SS.OSUSER ,
ST.SID "SID",
SN.NAME "TYPE",
CEIL(ST.VALUE / 1024 / 1024) "MB"
FROM V$SESSTAT ST
JOIN V$SESSION SS ON ST.SID = SS.SID
JOIN V$STATNAME SN ON ST.STATISTIC# = SN.STATISTIC#
WHERE UPPER(SN.NAME) LIKE '%PGA%'
AND SS.TYPE <> 'BACKGROUND'
ORDER BY ST.SID,ST.VALUE DESC