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RE: RE: Rollback Segment Problem

From: K Gopalakrishnan <kaygopal_at_yahoo.com>
Date: Thu, 14 Feb 2002 19:44:58 -0800
Message-ID: <F001.0041093A.20020214192824@fatcity.com> 






Gogala,



THe column you are looking is not the actual one. I have overlooked your
post and thought you are right. Now I have decided to test myself and here 
is the result.




SQL> select max(ktuxesqn) from X$KTuxe;



MAX(KTUXESQN)





          956



SQL> startup force pfile=c:\orawin\admin\test\pfile\init.ora
ORACLE instance started.



Total System Global Area   97283948 bytes

Fixed Size                   282476 bytes
Variable Size              62914560 bytes
Database Buffers           33554432 bytes
Redo Buffers                 532480 bytes


Database mounted.


Database opened.


SQL> select max(ktuxesqn) from X$KTuxe;



MAX(KTUXESQN)





          956



It is not getting changed by startup force.




Best Regards,


K Gopalakrishnan


Bangalore, INDIA





-----Original Message-----


Mladen


Sent: Thursday, February 14, 2002 2:42 PM
To: Multiple recipients of list ORACLE-L




Number of wraps gets reset with the instance. Below is the proof.
May be after the death of a rollback segment, when can have it's 
resurrection? What would we name it? A vampire rollback segment?
May be we should use documented V$ tables instead of the undocumented
X$ ones.




pdev3-a:dev:/oracle> sqlplus internal



SQL*Plus: Release 8.1.7.0.0 - Production on Thu Feb 14 17:26:02 2002



(c) Copyright 2000 Oracle Corporation.  All rights reserved.




Connected to:


Oracle8i Enterprise Edition Release 8.1.7.2.0 - 64bit Production
With the Partitioning option


JServer Release 8.1.7.2.0 - 64bit Production


SQL>
SQL>
SQL> select usn,wraps from v$rollstat;

       USN      WRAPS
---------- ----------
         0          0
         2          2
         3          3
         4          3
         5          2
         6          2





6 rows selected.



SQL> sshutdown immediate


SP2-0734: unknown command beginning "sshutdown ..." - rest of line ignored.
SQL> shutdown immediate


Database closed.


Database dismounted.


ORACLE instance shut down.


SQL> startup


ORACLE instance started.



Total System Global Area  114231784 bytes

Fixed Size                   104936 bytes
Variable Size              80039936 bytes
Database Buffers           33554432 bytes
Redo Buffers                 532480 bytes


Database mounted.


Database opened.


SQL> select usn,wraps from v$rollstat;



       USN      WRAPS



---------- ----------

         0          0
         2          0
         3          0
         4          0
         5          0
         6          0





6 rows selected.



SQL>


-----Original Message-----


Sent: Thursday, February 14, 2002 4:04 PM
To: Multiple recipients of list ORACLE-L




Gogala,



Not quite true.A simple restart will NOT cure that disease. The WRAP# is
visible as KTUXESQN in the X$KTUXE. You can check that value by restating
the instance. You can simply drop the rollback segment and force the
instance to use the other rollback segements, but not by restarting..:)




Best Regards,


K Gopalakrishnan


Bangalore, INDIA





-----Original Message-----


Mladen


Sent: Thursday, February 14, 2002 12:26 PM
To: Multiple recipients of list ORACLE-L




How long does a database have to remain running in order for a rollback
segment to go to the happy hunting grounds? Have you ever seen such an
event? A simple instance restart will cure that disease. Anyway, the only
thing that I can envision to cause this is to have an OLTP database with
something


like 1000000 online users doing more then 4000 transactions a day and the
instance is configured with a single rollback segment. In that case the
DBA deserves to be executed by the ways of the weight watchers!



-----Original Message-----


Sent: Thursday, February 14, 2002 2:36 PM
To: Multiple recipients of list ORACLE-L




Hi G_DBA ,



The transaction id (which is recorded in the ITL) consists of 3 components.
Undo Segment Number, Slot Number and Wrap Number.
THe max value of the wrap number is limited by UB4MAXVAL. (Approx 4G in
numbers) and once it reaches the MAXVAL the rollback segment is considered
as DEAD. i.e. it can not hold undo information for any transactions.,



THis condition is called as DEATH of a Rollback segment. THis is true for
SMU also.




Best Regards,


K Gopalakrishnan


Bangalore, INDIA





-----Original Message-----


Sent: Thursday, February 14, 2002 2:35 AM



Hi Ganesh,


Could u please elaborate, i did not get what u said.
What do u mean by Rollback segment dying.
I did not pick up the earlier mails so maybe thats why.
thanks and reg


Guru




On Thu, 14 Feb 2002 K Gopalakrishnan wrote :


> You never need to recreate the rollback segments (DROP

> and CREATE) unless

> the rollback segment dies. THe rollback segment will

> die after approx 4M

> (the number is not very accurate.. okay,, some number)

> transactions.

> THis is the only case I need to drop and recreate them.

>

> Best Regards,

> K Gopalakrishnan

> Bangalore, INDIA

>

>

>

> -----Original Message-----

> From: root_at_fatcity.com [mailto:root_at_fatcity.com]On

> Behalf Of Mohammad

> Rafiq

> Sent: Wednesday, February 13, 2002 9:54 AM

> To: Multiple recipients of list ORACLE-L

> Subject: RE: Rollback Segment Problem

>

>

> In many cases you will have to take RB segments offline

> and drop them, then

> re-create

>







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Author: K Gopalakrishnan
  INET: kaygopal_at_yahoo.com

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  INET: MGogala_at_oxhp.com

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Author: K Gopalakrishnan
  INET: kaygopal_at_yahoo.com

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Received on Thu Feb 14 2002 - 21:44:58 CST












Original text of this message













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