Oracle中SID的作用
SID 主要用于区分同一台计算机上的同一个数据库的不同实例.SID 与ORACLE_HOM 一起HASH 出来一个UNIQUE KEY NAME 分配给SGA.ORACL
SID 主要用于区分同一台计算机上的同一个数据库的不同实例.SID 与Oracle_HOM 一起HASH 出来一个UNIQUE KEY NAME 分配给SGA.
ORACLE 数据库服务器主要有两部分组成：物理数据库和数据库管理系统
数据库管理系统是用户和物理数据库之间的一个中间层, 是软件层. 这个软件层具有一定的结构, 这个结构又被称为例程结构.
在启动数据库时, ORACLE 首先要在内存中获取,划分,保留各种用途的区域, 运行各种用途的后台进程, 即创建一个例程( instance ) , 然后由该例程装载, 打开数据库, 最后由这个例程来访问和控制数据库的各种物理结构.
在启动数据库并使用数据库的时候, 实际上是连接到该数据库的例程, 通过例程来连接、使用数据库. 所以例程是用户和数据库之间的一个中间层.
例程是由操作系统的内存结构和一系列进程所组成的, 可以启动和关闭.
一台计算机上可以创建多个ORACLE 数据库, 当同时要使用这些数据库时, 就要创建多个例程. 为了不使这些例程相互混淆, 每个例程都要用称为SID 的符号来区分, 即创建这些数据库时填写的数据库SID.
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