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Home -> Community -> Mailing Lists -> Oracle-L -> RE: RE: Rollback Segment Problem
It's nice to see people appreciate learning something new!
-----Original Message-----
Sent: Friday, February 15, 2002 1:55 PM
To: Multiple recipients of list ORACLE-L
It might not get reset, but it's not a public information
and the behavior of it can change from one version to another .
It is unclear and undefined what happens when the number of transactions
on a rollback segments reaches the MAXVALUE. There are several
possibilities:
a) It wraps around and starts from 0, recording a carry.
b) It kills the affected rollback segment, thus forcing the DBA
to drop and re-create it.
c) It gets reset
Transaction ID (XID) consists of:
Rollback segment number (XIDUSN),
Rollback segment slot (entry in the transaction table, located in
the header of a rollback segment - XIDSLOT) and
the sequential number of transaction on that particular segment (XIDSQN)
since the creation of the rollback segment. I
I would hardly use the term "wrap" for the "transaction sequence".
-----Original Message-----
Sent: Thursday, February 14, 2002 9:23 PM
To: Multiple recipients of list ORACLE-L
The wrap# you're both talking about are completely different.
The wrap# that K Gopal means (that sequence number in the X$<table>) is a sequence number that keeps incrementing for every transaction happening in that transaction slot.
It never gets reset.
I remember reading when it reaches the higher limit, the RBS needs to be dropped.
It's easy to test:
Get the segment number for one of the rollback segments.
List the sequence numbers for all the slots in that RBS
using:
select ktuxesqn from x$ktuxe where ktuxeusn = the segment_number_for_the_RBS
SET transaction use rollback segment <the same rollback segment>
DO some inserts , updates
Commit;
select ktuxesqn from x$ktuxe where ktuxeusn = the segment_number_for_the_RBS
You will see that one of the numbers got incremented.
restart the database.
select ktuxesqn from x$ktuxe where ktuxeusn = the segment_number_for_the_RBS
Nothing changed.
Regards,
Waleed
-----Original Message-----
Sent: Thursday, February 14, 2002 7:13 PM
To: Multiple recipients of list ORACLE-L
Thanks for the correction. I was looking some other column. I am sorry for the mistake.
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$rollstat;
USN WRAPS
---------- ----------
0 0
2 2
3 3
4 3
5 2
6 2
6 rows selected.
SQL> sshutdown immediate
SP2-0734: unknown command beginning "sshutdown ..." - rest of line ignored.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.
Total System Global Area 114231784 bytes
Fixed Size 104936 bytes Variable Size 80039936 bytes Database Buffers 33554432 bytes Redo Buffers 532480 bytesDatabase mounted.
USN WRAPS
---------- ----------
0 0
2 0
3 0
4 0
5 0
6 0
6 rows selected.
SQL>
-----Original Message-----
Sent: Thursday, February 14, 2002 4:04 PM
To: Multiple recipients of list ORACLE-L
Gogala,
Not quite true.A simple restart will NOT cure that disease. The WRAP# is visible as KTUXESQN in the X$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
>
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: K Gopalakrishnan INET: kaygopal_at_yahoo.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Gogala, Mladen INET: MGogala_at_oxhp.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: K Gopalakrishnan INET: kaygopal_at_yahoo.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Gogala, Mladen INET: MGogala_at_oxhp.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: K Gopalakrishnan INET: kaygopal_at_yahoo.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Khedr, Waleed INET: Waleed.Khedr_at_FMR.COM Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Gogala, Mladen INET: MGogala_at_oxhp.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Khedr, Waleed INET: Waleed.Khedr_at_FMR.COM Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Fri Feb 15 2002 - 15:01:08 CST
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