RE: automatic undo 100% used

Paula, UNDO segments are created automa[t|g]ically in an UNDO tablespace. They are
the same good old rollback segments that you know and love from the previous versions,

only created automatically. They should never be truncated. System may offline some

of them in the times of plenty (low system activity), but the space should NEVER be released.

The worst thing imaginable, from the performance point of view, is to have the instance do dynamic

space allocation. If the space is allocated, that is because it was needed. If you de-allocate it,

it will be allocated again at some point, probably the least convenient one at that. That's Murphy.

You want to have a leeway for the segments to extend, so you should always have enough free

space to accommodate an additional segment. All of your DBA tables are still there and they still

apply. V$rollstat is replaced by v$undostat, but that's it.    

--

Mladen Gogala

Ext. 121

  _____  

From: Paula_Stankus_at_doh.state.fl.us [mailto:Paula_Stankus_at_doh.state.fl.us] 
Sent: Monday, December 13, 2004 2:08 PM
To: MGogala_at_allegientsystems.com
Subject: RE: automatic undo 100% used

 

Mladen,  I know you ask a lot of questions.  Seriously, is this how undo
segments work - is 100% of the tablespace allocated showing actually mean
that that much space is really being used?  Is there any problems with undo
segments (automatic) not actually releasing 

 

  _____  

From: Gogala, Mladen [mailto:MGogala_at_allegientsystems.com] 
Sent: Monday, December 13, 2004 1:59 PM
To: Stankus, Paula G; davidsharples_at_gmail.com; oracle-l_at_freelists.org
Subject: RE: automatic undo 100% used

Your logic would push storage manufacturers into recession. 
Don't you have any compassion for the poor workers in India and Malaysia? 
You are supposed to buy more disks and not ask any questions. 

-- 
Mladen Gogala 
Ext. 121 

-----Original Message----- 
From: Paula_Stankus_at_doh.state.fl.us [mailto:Paula_Stankus_at_doh.state.fl.us
<mailto:Paula_Stankus_at_doh.state.fl.us> ] 
Sent: Monday, December 13, 2004 1:16 PM 
To: davidsharples_at_gmail.com; oracle-l_at_freelists.org 
Subject: RE: automatic undo 100% used 

Have 3Gb allocated for undo retention, a few batch processes and 
tablespace is showing 100% full.  Is this normal behavior?  I am used to 
old rollback segments where it would be and likely revolve around poorly 
written batch processes. 
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