轉自: http://www.cnblogs.com/HondaHsu/archive/2009/08/14/1545914.html

select a.tablespace_name,a.bytes bytes_used,b.largest,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

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

查詢所有表空間的總容量、已經使用、剩餘、已經使用的百分比！

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

一般來說可以把上面的複雜的查詢語句放入一個檔案中，需要時再呼叫，或者建立一個試圖，需要時可以查詢。
1  寫入檔案:#vi /home/mzl/percent_used_tablespace.sql
內容：
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

2 匯入：
SQL> @/home/mzl/percent_used_tablespace.sql
SQL> l
  1  select a.tablespace_name,a.bytes "Sum",a.bytes-b.bytes "used",b.bytes "free",
  2  round(((a.bytes-b.bytes)/a.bytes)*100,2) "percent_used"
  3  from
  4  (select tablespace_name,sum(bytes) bytes from dba_data_files group by tablespace_name) a,
  5  (select tablespace_name,sum(bytes) bytes,max(bytes) largest from dba_free_space group by tablespace_name) b
  6  where a.tablespace_name=b.tablespace_name
  7* order by ((a.bytes-b.bytes)/a.bytes) desc
SQL> /

或者建立檢視：
SQL>create view percent
SQL>as
SQL>select a.tablespace_name,a.bytes/1024/1024 "Sum MB",(a.bytes-b.bytes)/1024/1024 "used MB",b.bytes/1024/1024 "free MB",
SQL>round(((a.bytes-b.bytes)/a.bytes)*100,2) "percent_used"
SQL>from
SQL>(select tablespace_name,sum(bytes) bytes from dba_data_files group by tablespace_name) a,
SQL>(select tablespace_name,sum(bytes) bytes,max(bytes) largest from dba_free_space group by tablespace_name) b
SQL>where a.tablespace_name=b.tablespace_name
SQL>order by ((a.bytes-b.bytes)/a.bytes) desc;

SQL> select * from percent;

查看錶空間的資料檔案是否是自動擴充套件：
SQL> l
  1* select file_name,tablespace_name,autoextensible from dba_data_files
SQL> /

FILE_NAME                                     TABLESPACE_NAME                AUT
--------------------------------------------- ------------------------------ ---
/u01/app/oracle/oradata/orcl/risenet.dbf      RISENET
/u01/app/oracle/oradata/orcl/perfstat.dbf     PERFSTAT                       NO
/u01/app/oracle/oradata/orcl/example01.dbf    EXAMPLE                        YES
/u01/disk1/users01.dbf                        USERS                          YES
/u01/app/oracle/oradata/orcl/sysaux01.dbf     SYSAUX                         YES
/u01/app/oracle/oradata/orcl/undotbs01.dbf    UNDOTBS1
/u01/disk2/system01.dbf                       SYSTEM                         YES
/u01/app/oracle/oradata/orcl/undotbs02.dbf    UNDOTBS2                       NO
/u01/disk1/pioneer_data.dbf                   PIONEER_DATA                   YES
/u01/disk2/pioneer_indx.dbf                   PIONEER_INDX                   NO
/u01/disk3/pioneer_undo.dbf                   PIONEER_UNDO                   NO

FILE_NAME                                     TABLESPACE_NAME                AUT
--------------------------------------------- ------------------------------ ---
/u01/app/oracle/oradata/orcl/paul01.dbf       PAUL                           NO
/u01/disk1/wenchuan.dbf                       WENCHUAN                       NO

13 rows selected.

比如表空間PIONEER_INDX已經用了83.33％，資料檔案不能自動擴充套件，可以修改成自動擴充套件，以免資料寫滿資料檔案。
SQL> alter database
  2  datafile '/u01/disk2/pioneer_indx.dbf'  autoextend on;

Database altered.

SQL> select file_name,tablespace_name,autoextensible from dba_data_files     
  2  where tablespace_name='PIONEER_INDX';

FILE_NAME                                     TABLESPACE_NAME                AUT
--------------------------------------------- ------------------------------ ---
/u01/disk2/pioneer_indx.dbf                   PIONEER_INDX                   YES

或者給表空間多加一個自動擴充套件的資料檔案,如果有多個硬碟，可以增加多個數據檔案（這樣多資料庫系統的併發性比較好）
SQL> alter tablespace pioneer_indx
  2  add datafile size 30M;

Tablespace altered.

SQL> select file_name,tablespace_name,bytes/1024/1024 "MB"  from dba_data_files
  2  where tablespace_name='PIONEER_INDX';

FILE_NAME                                     TABLESPACE_NAME
--------------------------------------------- ------------------------------
        MB
----------
/u01/disk2/pioneer_indx.dbf                   PIONEER_INDX
         6

/u01/disk5/ORCL/datafile/o1_mf_pioneer__45dpy PIONEER_INDX
fty_.dbf
        30