Below queries can be helpful to find details regarding temp tablespace usage.
Index
Temp segment usage per session
SELECT S.sid || ',' || S.serial# sid_serial, S.username, S.osuser, P.spid, S.module,
P.program, SUM (T.blocks) * TBS.block_size / 1024 / 1024 mb_used, T.tablespace,
COUNT(*) statements
FROM v$sort_usage T, v$session S, dba_tablespaces TBS, v$process P
WHERE T.session_addr = S.saddr AND S.paddr = P.addr
AND T.tablespace = TBS.tablespace_name
GROUP BY S.sid, S.serial#, S.username, S.osuser, P.spid, S.module, P.program, TBS.block_size, T.tablespace ORDER BY mb_used;
Temp segment usage per statement
SELECT S.sid || ',' || S.serial# sid_serial, S.username, Q.hash_value, Q.sql_text,
T.blocks * TBS.block_size / 1024 / 1024 mb_used, T.tablespace
FROM v$sort_usage T, v$session S, v$sqlarea Q, dba_tablespaces TBS
WHERE T.session_addr = S.saddr
AND T.sqladdr = Q.address
AND T.tablespace = TBS.tablespace_name ORDER BY mb_used;
Temp tablespace usage
select TABLESPACE_NAME, BYTES_USED, BYTES_FREE from V$TEMP_SPACE_HEADER;Hope this article will be helpful during troubleshooting of temp tablespace.