查看Oracle表空间大小及所剩空间大小

select f.tablespace_name, a.total, u.used, f.free, round((u.used / a.total) * 100) % USED,

select f.tablespace_name,
a.total,
u.used,
f.free,
round((u.used / a.total) * 100) "% USED",
round((f.free / a.total) * 100) "% FREE"
from (select tablespace_name, sum(bytes / (1024 * 1024)) total
from dba_data_files
group by tablespace_name) a,
(select tablespace_name, round(sum(bytes / (1024 * 1024))) used
from dba_extents
group by tablespace_name) u,
(select tablespace_name, round(sum(bytes / (1024 * 1024))) free
from dba_free_space
group by tablespace_name) f
where a.tablespace_name = f.tablespace_name
and a.tablespace_name = u.tablespace_name;

下面这种方法更快：

select a.tablespace_name,
a.bytes / 1024 / 1024 "Sum MB",
(a.bytes - b.bytes) / 1024 / 1024 "used MB",
b.bytes / 1024 / 1024 "free MB",
round(((a.bytes - b.bytes) / a.bytes) * 100, 2) "percent_used"
from (select tablespace_name, sum(bytes) bytes
from dba_data_files
group by tablespace_name) a,
(select tablespace_name, sum(bytes) bytes, max(bytes) largest
from dba_free_space
group by tablespace_name) b
where a.tablespace_name = b.tablespace_name
order by ((a.bytes - b.bytes) / a.bytes) desc;