本站中文解释
INSTANCE_NUMBER参数指定实例的数字编号，取值范围从0到32767，不能与其他实例相同（同一个数据库中只能有一个实例）。INSTANCE_NUMBER参数通常需要在新建实例时指定，当前用户下使用sqlplus连接数据库时，可以通过以下SQL语句来查看当前实例的INSTANCE_NUMBER：
SELECT instance_number FROM v$instance;
要更改INSTANCE_NUMBER参数的值，在内存中，需要使用以下SQL语句：
ALTER SYSTEM SET INSTANCE_NUMBER = SCOPE=MEMORY;
如果要在服务器重启后保存INSTANCE_NUMBER的值，需要在spfile或者动态参数文件（pfile）中修改相应的参数，然后进行重启。
官方英文解释
INSTANCE_NUMBER specifies a unique number that maps the instance to one free list group for each database object created with storage parameter FREELIST GROUPS.
| Property | Description |
|---|---|
|
Parameter type |
Integer |
|
Default value |
|
|
Modifiable |
No |
|
Modifiable in a PDB |
No |
|
Range of values |
1 to maximum number of instances specified when the database was created |
|
Basic |
Yes |
|
Oracle RAC |
You must set this parameter for every instance, and all instances must have different values. |
INSTANCE_NUMBER is an Oracle RAC parameter that can be specified in parallel mode or exclusive mode.
The INSTANCE parameter of the ALTER TABLE ... ALLOCATE EXTENT statement assigns an extent to a particular free list group. If you set INSTANCE_NUMBER to the value specified for the INSTANCE parameter, the instance uses that extent for inserts and for updates that expand rows.
The practical maximum value of this parameter is the maximum number of instances specified in the CREATE DATABASE statement. The absolute maximum is operating system-dependent.
See Also:
Oracle Real Application
Clusters Administration and Deployment Guide for more information
