Search notes:

Oracle: V$TEMPSEG_USAGE

select
   tus.username,
   ses.sid,
   ses.serial#,           -- same as tus.session_num
   tus.blocks,
   tus.extents,
-- tus."USER",            -- Obsolete and always equal to username. Use quotes to prevent ORA-01747
   tus.tablespace,
   tus.segtype,
   sqx.sql_text    txt_x,
   sqt.sql_text    txt_t,
   tus.contents,
   tus.segfile#,
   tus.segblk#,
   tus.ts#,
   tus.sql_id,
   tus.sql_id_tempseg
from
   v$tempseg_usage  tus                                    left join
   v$session        ses on tus.session_addr   = ses.saddr  left join
   v$sqlarea        sqx on tus.sql_id         = sqx.sql_id left join
   v$sqlarea        sqt on tus.sql_id_tempseg = sqt.sql_id;

See also

v$sort_usage is a synonym that also points to v_$tempseg_usage.
v$temp_space_header
Oracle Dynamic Performance Views

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