如何区分一个初始化参数是静态还是动态的

如何区分一个初始化参数是静态还是动态的

 

在Oracle中，从9i开始引入了spfile，也就是服务器端初始化参数，有很多是可以支持在线修改的，也就是修改会马上生效，详细内容看下面的说明：

 

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 immediately upon being changed.

 

SQL> select distinct issys_modifiable from v$parameter;

 

ISSYS_MODIFIABLE

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

DEFERRED

FALSE

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.