To be performed off hours
SQL> SELECT tablespace_name, file_name, bytes
FROM dba_temp_files WHERE tablespace_name = 'TEMP';
SQL> ALTER DATABASE TEMPFILE '/u02/oradata/TESTDB/temp01.dbf' DROP INCLUDING DATAFILES;
SQL> ALTER TABLESPACE temp ADD TEMPFILE '/u02/oradata/TESTDB/temp01.dbf' SIZE 512m
AUTOEXTEND ON NEXT 250m MAXSIZE UNLIMITED;