- Administration
- Structure
- Performance
- Backup
- Miscellaneous
- SQL*Net
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Structure - Undo
Display the rollback segments
select segment_name
, status
from dba_rollback_segs
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Alter undo retention
alter system set undo_retention=500 scope=memory;
Note. This is in seconds
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What's in undo
select tablespace_name
, status
, count(*) as HOW_MANY
from dba_undo_extents
group by tablespace_name
, status
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Is anything rolling back at the moment?
Look for the used_ublk value decreasing. If it is, the session connected with it is rolling back. When it reaches zero, rollback is complete.
set lines 100 pages 999
col username format a15
col command format a20
select ses.username
, substr(ses.program, 1, 19) command
, tra.used_ublk
from v$session ses
, v$transaction tra
where ses.saddr = tra.ses_addr
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