Integer 

Static 

Lowest available number (depends on instance startup order and on the INSTANCE_NUMBER values assigned to other instances).

0 if not configured for Oracle Parallel Server. 

1 to maximum number of instances specified when the database was created 

Multiple instances need not specify, but must have different values if they do specify. You can change the values if necessary. 

INSTANCE_NUMBER is an Oracle Parallel Server 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.

See Also: Oracle8i Parallel Server Administration, Deployment, and Performance for more information.