CREATE ROLLBACK SEGMENT
CREATE [PUBLIC] ROLLBACK SEGMENTsegment_name
TABLESPACEtablespace_name
[STORAGE ( [INITIALinteger
[K | M] ] [NEXTinteger
[K | M] ] [MINEXTENTSinteger
[K | M] ] [MAXEXTENTS {integer
| UNLIMITED} ] [PCTINCREASEinteger
] [FREELISTSinteger
] [FREELIST GROUPSinteger
] ] [OPTIMAL {integer
[K | M] | NULL} ] ) ]
Creates a rollback segment (segment_name), which is used by Oracle to store data necessary to roll back changes made by transactions.
Specifies that this rollback segment is available to any instance. If PUBLIC is omitted, it is only available to the instance naming it in the ROLLBACK_SEGMENTS parameter in the INIT.ORA file.
Specifies the tablespace (tablespace_name) where this rollback segment will be created.
Specifies the physical characteristics of the rollback segment as follows:
Specifies the size of the first extent for this rollback segment in bytes, kilobytes, or megabytes. If this value is not a multiple of the database blocksize, it will be rounded up to a multiple of the database blocksize.
Specifies the size of the next extent in bytes, kilobytes, or megabytes. If this value is not a multiple of the database blocksize, it will be rounded up to a multiple the of database blocksize.
Specifies the number of extents to be allocated when this rollback segment is created. The minimum number of extents for a rollback segment is 2, and this is the default.
Specifies the maximum number of extents that may be allocated for this rollback segment. The default will vary according to the database blocksize. Specify UNLIMITED for unlimited expansion.
Specifies the percentage by which each extent will grow over the previous extent. The default is 50, which means that each extent will be one-and-one-half times larger than the previous extent. It is recommended that rollback segments use a PCTINCREASE value of 0, in order to allocate equal-size extents.
Specifies the number of free lists contained in each freelist group in this rollback segment. The default is 1, and the maximum depends on the database blocksize.
Specifies the number of groups of free lists for this rollback segment. The default is 1. This parameter should be used only with the Parallel Server option running in parallel mode.
Specifies the optimal size for this rollback segment. Oracle will attempt to maintain this size by deallocating unused extents. The default is NULL, which means that no deallocation will ever take place.
You must have the CREATE ROLLBACK SEGMENT privilege to issue this command. The tablespace must be online for you to create a rollback segment in it. When it is created, the rollback segment will be offline and must be brought online by using the ALTER ROLLBACK SEGMENT statement or restarting the database with the rollback segment named in the INIT.ORA file.