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


Default value

0 (zero)



Modifiable in a PDB


Range of values

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



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.