Oracle9i SQL Reference Release 1 (9.0.1) Part Number A90125-01 |
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SQL Statements:
CREATE LIBRARY to CREATE SPFILE, 13 of 16
Use the CREATE
ROLLBACK
SEGMENT
statement to create a rollback segment, which is an object that Oracle uses to store data necessary to reverse, or undo, changes made by transactions.
The information in this section assumes that your database is running in rollback undo mode (the UNDO_MANAGEMENT
initialization parameter is set to MANUAL
or not set at all).
If your database is running in Automatic Undo Management mode (the UNDO_MANAGEMENT
initialization parameter is set to AUTO
), then user-created rollback segments are irrelevant. In this case, Oracle returns an error in response to any CREATE
ROLLBACK
SEGMENT
or ALTER
ROLLBACK
SEGMENT
statement. To suppress these errors, set the UNDO_SUPPRESS_ERRORS
parameter to TRUE
.
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To create a rollback segment, you must have CREATE
ROLLBACK
SEGMENT
system privilege.
create_rollback_segment::=
create_rollback_segment
storage_clause: See storage_clause.
Specify PUBLIC
to indicate that the rollback segment is public and is available to any instance. If you omit this clause, the rollback segment is private and is available only to the instance naming it in its initialization parameter ROLLBACK_SEGMENTS
.
Specify the name of the rollback segment to be created.
Use the TABLESPACE
clause to identify the tablespace in which the rollback segment is created. If you omit this clause, Oracle creates the rollback segment in the SYSTEM
tablespace.
Restriction: You cannot create a rollback segment in a tablespace that is system managed (that is, during creation you specified EXTENT
MANAGEMENT
LOCAL
AUTOALLOCATE
).
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The storage_clause
lets you specify the characteristics for the rollback segment.
CREATE
ROLLBACK
SEGMENT
ExampleThe following statement creates a rollback segment with default storage values in the system tablespace:
CREATE ROLLBACK SEGMENT rbs_1TABLESPACE system;
The above statement is equivalent to the following:
CREATE ROLLBACK SEGMENT rbs_2 TABLESPACE system STORAGE ( INITIAL 10K NEXT 10K MAXEXTENTS UNLIMITED);
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