数据库默认临时表空间
作者:gototop
在9i之前,假如一个数据库用户没有被指定默认临时表空间,那么Oracle就会使用system表空间作为该用户的临时表空间,这是很危险的。在9i里面,database可以被指定一个默认临时表空间。这样假如数据库用户没有被明确指定临时表空间,oracle 9i就会自动指定database的默认临时表空间作为该用户的临时表空间。
我们可以通过下面的语句来查询数据库的默认临时表空间:
SQL select * from database_properties where property_name = 'DEFAULT_TEMP_TABLESPACE';
PROPERTY_NAME PROPERTY_VALUE DESCRIPTION
--------------------- ------------------- ------------------------
DEFAULT_TEMP_TABLESPACE TEMP Name of default temporary tablespace
默认临时表空间的限制:
1. 默认临时表空间必须是TEMPORARY的:
SQL alter database default temporary tablespace tools;
alter database default temporary tablespace tools
*
ERROR at line 1:
ORA-12902: default temporary tablespace must be SYSTEM or of TEMPORARY type
2. 默认临时表空间一旦被指定,将无法在改成PERMANET:
SQL alter tablespace temp2 permanent;
alter tablespace temp2 permanent
*
ERROR at line 1:
ORA-12904: default temporary tablespace cannot be altered to PERMANENT type
3. 在删除默认临时表空间必须先重新指定默认临时表空间:
SQL drop tablespace temp including contents and datafiles;
drop tablespace temp including contents and datafiles
*
ERROR at line 1:
ORA-12906: cannot drop default temporary tablespace
SQL create tablespace TEMP2
2 datafile '/data1/ora9data/temp2_01.dbf'
3 size 100k TEMPORARY;
Tablespace created.
SQL alter database default temporary tablespace TEMP2;
Database altered.
SQL drop tablespace temp including contents and datafiles;
Tablespace dropped.
4. 默认临时表空间无法OFFLINE:
SQL alter tablespace temp offline;
alter tablespace temp offline
*
ERROR at line 1:
ORA-12905: default temporary tablespace cannot be brought OFFLINE
5. 用户的临时表空间必须是TEMPORARY的(在9i之前没有这个限制,可以是PERMANENT):
SQL alter user scott temporary tablespace TOOLS;
alter user scott temporary tablespace TOOLS
*
ERROR at line 1:
ORA-12911: permanent tablespace cannot be temporary tablespace
SQL create tablespace temp2
2 datafile '/data1/ora9data/temp2_01.dbf'
3 size 100k temporary;
Tablespace created.
SQL alter user scott temporary tablespace temp2;
User altered.
6. 假如删除了用户的临时表空间,而这个临时表空间又不是数据库的默认临时表空间(假如是数据库的默认临时表空间是删不掉的),用户的临时表空间不会自动转换到数据库的默认临时表空间上:
SQL select tablespace_name, contents from dba_tablespaces where tablespace_name like 'TEMP%';
TABLESPACE_NAME CONTENTS
------------------------------ ---------
TEMP TEMPORARY
TEMP2 TEMPORARY
SQL select TEMPORARY_TABLESPACE from dba_users where username='SCOTT';
TEMPORARY_TABLESPACE
------------------------------
TEMP2
SQL drop tablespace TEMP2 including contents and datafiles;
Tablespace dropped.
SQL select TEMPORARY_TABLESPACE from dba_users where username='SCOTT';
TEMPORARY_TABLESPACE
------------------------------
TEMP2