ALTER ROLLBACK SEGMENT

Take an existing RBS on-line or off-line or change its storage parameters.

Syntax:

   ALTER ROLLBACK SEGMENT rbs_name {ONLINE | OFFLINE}

   ALTER ROLLBACK SEGMENT rbs_name STORAGE storage_clause

   ALTER ROLLBACK SEGMENT rbs_name SHRINK [TO int {K | M}]

If you use rollback segments to manage undo space, you are operating in manual undo management mode.

If you use an undo tablespace, you are operating in automatic undo management mode. You determine the mode at instance startup using theUNDO_MANAGEMENT initialization parameter. See the Oracle9i Database Reference for further information.

To monitor rollback usage (waits/gets should be < 1 %)

select name, waits, gets
from v$rollstat, v$rollname
where v$rollstat.usn = v$rollname.usn;

"Never mistake motion for action" - Ernest Hemmingway

Related Commands:

CREATE ROLLBACK SEGMENT
DROP ROLLBACK SEGMENT
ORA-01555 - Snapshot too old (Rollback has been overwritten)

Related Views:

 DBA_ROLLBACK_SEGS
 V$ROLLNAME
 V$ROLLSTAT