DBA_UNDO_EXTENTS describes the extents comprising the segments in all undo tablespaces in the database.
Note:
The status of the undo space distribution reported byDBA_UNDO_EXTENTS is correct for the undo tablespace that is active on the instance on which DBA_UNDO_EXTENTS is queried. However, due to the use of in-memory information that is different on each instance, there can be a discrepancy in the status of the undo space distribution of undo tablespaces active on other instances when queried from one instance. This does not affect undo functionality and is only a reporting discrepancy for other instances' undo tablespace space distribution status. As a best practice, query the space distribution for an undo tablespace from the instance on which it is active.| Column | Datatype | NULL | Description |
|---|---|---|---|
OWNER |
CHAR(3) |
Owner of the undo tablespace | |
SEGMENT_NAME |
VARCHAR2(30) |
NOT NULL |
Name of the undo segment |
TABLESPACE_NAME |
VARCHAR2(30) |
NOT NULL |
Name of the undo tablespace |
EXTENT_ID |
NUMBER |
ID of the extent | |
FILE_ID |
NUMBER |
NOT NULL |
File identifier number of the file containing the extent |
BLOCK_ID |
NUMBER |
Start block number of the extent | |
BYTES |
NUMBER |
Size of the extent (in bytes) | |
BLOCKS |
NUMBER |
Size of the extent (in blocks) | |
RELATIVE_FNO |
NUMBER |
Relative number of the file containing the segment header | |
COMMIT_JTIME |
NUMBER |
Commit time of the undo in the extent expressed as Julian time. This column is deprecated, but retained for backward compatibility reasons. | |
COMMIT_WTIME |
VARCHAR2(20) |
Commit time of the undo in the extent expressed as Wallclock time.This column is deprecated, but retained for backward compatibility reasons. | |
STATUS |
VARCHAR2(9) |
Transaction Status of the undo in the extent:
|