difference between ALTER SYSTEM and ALTER DATABASE

http://www.dbasupport.com/forums/archive/index.php/t-48720.html 참고


ALTER SYSTEM statement to dynamically alter your Oracle instance.
The settings stay in effect as long as the database is mounted.

 

ALTER DATABASE statement to modify, maintain, or recover an existing database.  

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https://kr.forums.oracle.com/forums/thread.jspa?threadID=933081 참고

ALTER SYSTEM is an Instance Level command. Generally this applies for running processes, parameters etc. (however "ALTER SYSTEM DUMP" seems to be an exception).

ALTER DATABASE is a Database Level command. Generally, this applies to the physical structure of the database.

Think of an RAC environment.
Most ALTER SYSTEM commands (ALTER SYSTEM DUMP is one exception) are local to the instance (although SET can set for multiple instances).
The ALTER DATABASE commands are for the whole database.