INSTANCE_NUMBER

Property	Description
Parameter type	Integer
Default value	0 (zero)
Modifiable	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. It specifies a unique number that maps the instance to one free list group for each database object created with storage parameter FREELIST GROUPS.

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.