Oracle 線上生效的初始化參數判定

當使用spfile時，不用重啟就能生效的初始化參數，可以通過v$parameter.ISSYS_MODIFIABLE欄位來判斷。

v$parameter.ISSYS_MODIFIABLE參數

Indicates whether the parameter can be changed with ALTER SYSTEM and when the change takes effect:

IMMEDIATE - Parameter can be changed with ALTER SYSTEM regardless of the type of parameter file used to start the instance. The change takes effect immediately.

DEFERRED - Parameter can be changed with ALTER SYSTEM regardless of the type of parameter file used to start the instance. The change takes effect in subsequent sessions.

FALSE - Parameter cannot be changed with ALTER SYSTEM unless a server parameter file was used to start the instance. The change takes effect in subsequent instances.

1. SQL>  select distinct issys_modifiable from v$parameter;  
2.    
3. ISSYS_MODIFIABLE  
4. ----------------   
5. IMMEDIATE  
6. FALSE  
7. DEFERRED  
8.   
9. SQL>  select  name,issys_modifiable from v$parameter where name='sga_target';  
10.    
11. NAME                                                                             ISSYS_MODIFIABLE  
12. -------------------------------------------------------------------------------- ----------------   
13. sga_target                                                                       IMMEDIATE  
14. SQL>  select  name,issys_modifiable from v$parameter where name='remote_login_passwordfile';  
15.    
16. NAME                                                                             ISSYS_MODIFIABLE  
17. -------------------------------------------------------------------------------- ----------------   
18. remote_login_passwordfile                                                        FALSE