動態引數,靜態引數

靜態引數： 修改後必須重啟才能生效
動態引數：修改後立即生效

當使用spfile的情況下，動態和靜態引數都可以透過：

Alter system 全部會話有效.

Alter system set  xxx=xxx; 同時更新spfile和memory內容

Alter system set xxx=xxx scope = spfile|memory; 只更新一個地方的.

 

對於動態引數，還可以透過

Alter session set xxx=xxx; 來修改引數值，但只對當前會話有效.

  在Oracle中，從9i開始引入了spfile，也就是伺服器端初始化引數，有很多是可以支援線上修改的，也就是修改會馬上生效，詳細內容看下面的說明：

The ISSYS_MODIFIABLE column in V$PARAMETER tells us whether the parameters are static or dynamic. Static parameters require the instance to be restarted while dynamic parameters can take effect（生效） immediately upon（在…之後） being changed.

SQL> select distinct issys_modifiable from v$parameter;

 

ISSYS_MODIFIABLE

---------------------------

DEFERRED

FALSE       ----表明為靜態的

IMMEDIATE

 

If the ISSYS_MODIFIABLE value is set to FALSE for a parameter, it means that the parameter cannot change its value in the lifetime of the instance; the database needs to be restarted for changes to take effect.

A parameter set to IMMEDATE value means that it is dynamic and can be set to change the present active instance as well as future database restarts.

A parameter set to DEFERRED is also dynamic, but changes only affect subsequent sessions, currently active sessions will not be affected and retain the old parameter value.