https://blog.csdn.net/dba_monkey/article/details/60141467

scope=memory scope=spfile scope=both 动态修改
scope=memory;---直接修改内存中的值
scope=spfile;---只改的磁盘上的参数，没有更改内存
scope=both;--同时修改内存和磁盘

ALTER SYSTEM 中 SCOPE=SPFILE/MEMORY/BOTH 的区别：
SCOPE = SPFILE
 The change is applied in theserverparameter file only. The effect is as follows:
■ For dynamic parameters, the change is effective at the next startup and is persistent.
■ For static parameters, the behavior. is the same as for dynamic parameters. This is the only SCOPE specification allowed for static parameters.
（此更改写入初始化参数文件，更改将在下次启动时生效。动态参数与静态参数都一样可以。也是静态参数唯一可以使用的方式。）

SCOPE = MEMORY
The change is applied in memory only. The effect is as follows:
■ For dynamic parameters, the effect is immediate, but it is not persistent because the server parameter file is not updated.
■ For static parameters, this specification is not allowed.
（只在内存上修改，立即生效，但重启后将不再生效，因为并没有写入到初始化参数文件。只适用于动态参数，静态参数则不允许。）

SCOPE = BOTH
The change is applied in both the server parameter file and memory. The effect is as follows:
■ For dynamic parameters, the effect is immediate and persistent.
■ For static parameters, this specification is not allowed.
（既写入到初始化参数文件，也在内存上修改，立即生效。同样也只适用于动态参数，静态参数则不允许。）