Oracle SQL: the Essential Reference

CREATE/ALTER/DROP ROLLBACK SEGMENT

CREATE [PUBLIC] ROLLBACK SEGMENT segment_name TABLESPACE tablespace [STORAGE Storage_Clause]

Creates a rollback segment, which Oracle uses to store data necessary to roll back changes made by transactions.

ALTER ROLLBACK SEGMENT segment_name 
  [STORAGE Storage_Clause]
  [ONLINE | OFFLINE] 
  [SHRINK]

Changes the online status of a rollback segment or modifies storage characteristics.

DROP ROLLBACK SEGMENT segment_name

Removes a rollback segment from the database.

Keywords

PUBLIC

Specifies that this rollback segment is available to any instance. If omitted, it is only available to the instance naming it in the ROLLBACK_SEGMENTS parameter in the INIT.ORA file.

segment_name

Name of the rollback segment to be created.

TABLESPACE

Specifies the name of the tablespace where this rollback segment will be created.

STORAGE

Specifies the physical storage characteristics. See Chapter 4 for detailed information.

ONLINE

Specifies that the named rollback segment be brought online.

OFFLINE

Specifies that the named rollback segment be taken offline.

SHRINK

Specifies that the named rollback segment should be reduced to the size specified, or to the OPTIMAL size if no size is specified.

When it is created, a rollback segment will be offline. It must be brought online by using the ALTER ROLLBACK SEGMENT statement or by restarting the database with the rollback segment ...