DBA_ROLLBACK_SEGS describes rollback segments.
| Column | Datatype | NULL | Description | 
|---|---|---|---|
| SEGMENT_NAME | VARCHAR2(30) | NOT NULL | Name of the rollback segment | 
| OWNER | VARCHAR2(6) | Owner of the rollback segment: 
 | |
| TABLESPACE_NAME | VARCHAR2(30) | NOT NULL | Name of the tablespace containing the rollback segment | 
| SEGMENT_ID | NUMBER | NOT NULL | ID number of the rollback segment | 
| FILE_ID | NUMBER | NOT NULL | File identifier number of the file containing the segment head | 
| BLOCK_ID | NUMBER | NOT NULL | ID number of the block containing the segment header | 
| INITIAL_EXTENT | NUMBER | Initial extent size in bytes | |
| NEXT_EXTENT | NUMBER | Secondary extent size in bytes | |
| MIN_EXTENTS | NUMBER | NOT NULL | Minimum number of extents | 
| MAX_EXTENTS | NUMBER | NOT NULL | Maximum number of extent | 
| PCT_INCREASE | NUMBER | Percent increase for extent size | |
| STATUS | VARCHAR2(16) | Rollback segment status: 
 | |
| INSTANCE_NUM | VARCHAR2(40) | Rollback segment owning Real Application Clusters instance number | |
| RELATIVE_FNO | NUMBER | NOT NULL | Relative file number of the segment header |