oracle undo usage per session
-- UNDOTBS usage per User: SELECT u.TABLESPACE_NAME AS TABLESPACE, s.USERNAME, u.STATUS, sum(u.BYTES) / 1024 / 1024 AS SUM_IN_MB, count(u.SEGMENT_NAME) AS SEG_CNTS FROM DBA_UNDO_EXTENTS u, V$TRANSACTION T, V$SESSION s WHERE T.ADDR = s.TADDR GROUP BY u.TABLESPACE_NAME, s.USERNAME, u.STATUS ORDER BY 1, 2, 3;