SM$TS_USED,SM$TS_FREE,SM$TS_AVAIL

SM$TS_USED,SM$TS_FREE,SM$TS_AVAIL，这三个在Oracle官方文档的reference上找不到相关解释。其实三者都是视图，从DBA_VIEWS中可以得到相关信息。

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1. SYS@ORCL> desc SM$TS_USED
   
2.  Name                                 Null? Type
   
3.  ----------------------------------------------------------------- -------- --------------------------------------------
   
4.  TABLESPACE_NAME                             VARCHAR2(30)
   
5.  BYTES                                     NUMBER
   
6. 
   
7. SYS@ORCL> desc SM$TS_FREE
   
8.  Name                                 Null? Type
   
9.  ----------------------------------------------------------------- -------- --------------------------------------------
   
10.  TABLESPACE_NAME                             VARCHAR2(30)
    
11.  BYTES                                     NUMBER
    
12. 
    
13. SYS@ORCL> desc SM$TS_AVAIL
    
14.  Name                                 Null? Type
    
15.  ----------------------------------------------------------------- -------- --------------------------------------------
    
16.  TABLESPACE_NAME                             VARCHAR2(30)
    
17.  BYTES                                     NUMBER

SYS@ORCL> select view_name,text_length,text from dba_views where view_name='SM$TS_USED';


VIEW_NAME       TEXT_LENGTH
------------------------------ -----------
TEXT
--------------------------------------------------------------------------------
SM$TS_USED 87
select tablespace_name, sum(bytes) bytes from dba_segments
    group by tablespa（ce_name ）
意即该视图是上述查询中的text列所示SQL语句的等效视图，如下可证明该结论：
SYS@ORCL> select tablespace_name,sum(bytes) bytes from dba_segments
  2  group by tablespace_name;

TABLESPACE_NAME    BYTES
------------------------------ ----------
SYSAUX 561971200
UNDOTBS1 20971520
USERS  3211264
SYSTEM 793051136
EXAMPLE 324206592

SYS@ORCL> select * from sm$ts_used;

TABLESPACE_NAME    BYTES
------------------------------ ----------
SYSAUX 561971200
UNDOTBS1 20971520
USERS  3211264
SYSTEM 793051136
EXAMPLE 324206592

剩下二者同上
SYS@ORCL> select view_name,text_length,text from dba_views where view_name='SM$TS_FREE';

VIEW_NAME       TEXT_LENGTH
------------------------------ -----------
TEXT
--------------------------------------------------------------------------------
SM$TS_FREE 89
select tablespace_name, sum(bytes) bytes from dba_free_space
    group by tables

SYS@ORCL> select view_name,text_length,text from dba_views where view_name='SM$TS_AVAIL';

VIEW_NAME       TEXT_LENGTH
------------------------------ -----------
TEXT
--------------------------------------------------------------------------------
SM$TS_AVAIL 89
select tablespace_name, sum(bytes) bytes from dba_data_files
    group by tables

by the way， SM$TS_USED,SM$TS_FREE,SM$TS_AVAIL，个人觉得sm有可能是sum的简写，ts则是tablespaces的简写。

感谢ORA-600的提示:-)

@760