database与instance区别

database与instance区别

原创:http://blog.youkuaiyun.com/haifenglong/article/details/5347322

拜读过thomas kyte的大作后对database和instance有更深入的理解了。

Database:A collection of physical operating system files or disk. When using Oracle 10g
Automatic Storage Management (ASM) or RAW partitions, the database may not appear
as individual separate files in the operating system, but the definition remains the
same.

 

数据库其实就是存储在操作系统或磁盘上的文件集合。

 

Instance: A set of Oracle background processes/threads and a shared memory area,
which is memory that is shared across those threads/processes running on a single
computer. This is the place to maintain volatile, nonpersistent stuff (some of which gets
flushed to disk). A database instance can exist without any disk storage whatsoever. It
might not be the most useful thing in the world, but thinking about it that way will definitely
help draw the line between the instance and the database.

 

实例就是Oracle后台进程/线程和共享内存区的集合。

 

我们使用create database语句的应该叫创建数据库而不应该叫创建实例，库是Oracle最大的概念了。