Temporary Tablespace Usage

I use below query to find temporary tablespace usage:


select b.tablespace_name,
b.SizeMB,
nvl(a.UsageMB, 0) as UsageMB,
b.SizeMB - nvl(a.UsageMB, 0) as FreeMB
from (select sum(BLOCKS) * b.VALUE / 1024 / 1024 as UsageMB,
tablespace as tablespace_name
from v$tempseg_usage a, v$parameter b
where b.name = 'db_block_size'
group by TABLESPACE, b.VALUE) a,
(select sum(bytes) / 1024 / 1024 as SizeMB, tablespace_name
from dba_temp_files
group by tablespace_name) b
where a.tablespace_name(+) = b.tablespace_name;