One sytem rollback segment though AUM

Hello guys,
i know from oracle documentation and experience that there exists one rollback segment in system until the initial installation... but why?
Why can oracle not use the undo tablespace for this rollback segment if i use AUM? Can i delete this one or is it necessary after the installation too?
Maybe someone of you has an explanation for that.
Thanks and Regards
Stefan

Hi Dim,
no... if you have a closer look... you will see one rollback segment in system ... though if you are using Automatic Undo Mangagment (UNDO Tablespace).
As i see in your profile... you are german too... have a closer look at this document:
-> http://www.ordix.de/ORDIXNews/4_2002/db_2.html
Auch im automatischen Modus des UNDO Managements befindet sich im SYSTEM Tablespace ein Rollback Segment, welches beim Erstellen der Datenbank erzeugt wirdThere is described that also one segment exists (always!) ... but why?
Regards
Stefan

Similar Messages

SYSTEM Rollback Segment

I had 7 system rolback segment in my database. I know about the one but i don't know how the other 6 are created.
Can I take the other 6 system rollback segment offline and drop?
Did they hurst the database ?

<<I have multiple system Rollback segment in my database. I want to keep one system rollback segment.>>
why do you want to offline remainning rollback segment.
if u offline rollback segments then it will effect the performance.
i think you should read first rollback segment concept guide.
http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96521/undo.htm#9114
Thanks and Regards
Kuljeet pal singh

Can rollback segments span one datafile like data segments

1.Can rollback segments span one datafile like data segments?
For e.g we have undo tablespace with 2 data files
We have one active transaction in rbs01,now when rollback segment grows and extents are allocated to it ,if all the extents will be allocated to one data file or it can be allocated to any of the two data file.
2.Can we set the transaction to a particular rollback segment when undo_management parameter is set to AUTO?

1.Can rollback segments span one datafile like data
segments?
For e.g we have undo tablespace with 2 data files
We have one active transaction in rbs01,now when
rollback segment grows and extents are allocated to
it ,if all the extents will be allocated to one data
file or it can be allocated to any of the two data
file.I don't think so. E.g. if you have a long transaction, you will need to create a larger RB segment and allocate this segment to be used. That's why you should be using automatic undo management as opposed to manual rollback segments.
2.Can we set the transaction to a particular rollback
segment when undo_management parameter is set to AUTO?No, when you use automatic undo management, you create one tablespace for undo management. THere is no concept of individual rollback segments.

Which rollback segment ???

rdbms 9207
is there a way to tell which rollback segments a process used after it has been executed. i have a script that will give me some good info on rbsegs during execution but that's not what i want. i have a process running for more than an hour that is using "set transaction use rollback segment rbsxl;" it does several commits and then issues the set stmnt after every commit. anyway... problem is... sometimes it blows up because it grabs a different rollback segment which are all smaller than rbsxl. sqltrace hasn't seemed to help. statspack?? oem?? any ideas??
would love to know where it's grabbing this other rbseg. even a mod to the program to output the current rbseg would be nice.... just don't know how.
thanks
-doug-

Hmm...some thoughts:
1.) Since you're on 9.2, why not moveto AUM? Much easier to deal with.
2.) If you want to stick w/ conventional rollback segments, you ought to make sure they are equisized (governed by optsize) and are able to grow enough to fit your needs (based on free space in the rollback segment tablespace).
3.) If you really want to just see what's going on w/ the code, try a 10046 trace. Everything should be captured there, including all 'set transaction use rollback segment' statements, and it may help you identify if there are any commits that are not followed by a 'set transaction use rollback segment' statement. My guess is that after one of the commits, you missed a 'set transaction ...' statement.
Hope that helps,
-Mark

Forcing a specific rollback segment on a transaction does not seem to work

Hi!
We're using Oracle 9.2.0.5.0 on Sun Solaris and we're still configured to use Rollback Segments.
We have an issue with Snapshot too old due to RBS too small on a long query I attach below for reference:
set heading off
set pagesize 0
set feedback off
set linesize 200
<<<<< SET TRANSACTION USE ROLLBACK SEGMENT UMF_RBS_LARGE_TRAN; <<<<<
SELECT ucms_cards.msisdn
|| ';;' || to_char(to_date(substr(ucms_cards.notes,14+length(ucms_cards.msisdn),19),'MM-DD-YYYY.HH24-MI-SS'),'DD/MM/YYYY HH24:MI:SS')
|| ';;' || to_char(ucms_batches.expiry_date,'dd/mm/yyyy')
|| ';;' || ucms_cards.serial_no
|| ';;' || ucms_cards.serial_no
|| ';;' || ucms_cards.batch_serial_no
|| ';;' || ' '
|| ';;' || CASE ucms_cards.card_status
WHEN 'used' THEN '1'
ELSE '0'
END
|| ';;' || CASE WHEN date_booked_in is null THEN '01/01/1970 00:00:00' ELSE to_char(date_booked_in,'DD/MM/YYYY') || ' 00:00:00' END
|| ';;' || ' '
from ucms_batches,ucms_cards, UCMS_EVENT_LOG
WHERE ucms_cards.batch_serial_no = ucms_batches.serial_no
AND ucms_cards.serial_no = substr(UCMS_EVENT_LOG.ENTITY_ID,11,length(UCMS_EVENT_LOG.ENTITY_ID)-9)
AND UCMS_EVENT_LOG.PARTY_NO in (0)
AND UCMS_EVENT_LOG.TIMESTAMP>=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 00:00:01', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.TIMESTAMP<=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 23:59:59', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.USER_ID LIKE 'SCP-AGENT1%'
AND UCMS_EVENT_LOG.EVENT_TYPE_ID IN (1,2)
AND UCMS_EVENT_LOG.ENTITY_TYPE_ID LIKE 'ucms_cards%'
UNION
SELECT ucms_imported_cards.msisdn
|| ';;' || to_char(to_date(substr(ucms_imported_cards.notes,14+length(ucms_imported_cards.msisdn),19),'MM-DD-YYYY.HH24-MI-SS'),'DD/MM/YYYY H24:MI:SS')
|| ';;' || to_char(ucms_imported_cards.expiry_date,'dd/mm/yyyy')
|| ';;' || ucms_imported_cards.serial_no
|| ';;' || ucms_imported_cards.serial_no
|| ';;' || DBMS_UTILITY.GET_HASH_VALUE(ucms_imported_cards.card_type,1,65536)
|| ';;' || ' '
|| ';;' || CASE ucms_imported_cards.card_status
WHEN 'used' THEN '1'
ELSE '0'
END
|| ';;' || '01/01/1970 00:00:00'
|| ';;' || ' '
from ucms_imported_cards, UCMS_EVENT_LOG
where ucms_imported_cards.serial_no = substr(UCMS_EVENT_LOG.ENTITY_ID,11,length(UCMS_EVENT_LOG.ENTITY_ID)-9)
AND UCMS_EVENT_LOG.PARTY_NO in (0)
AND UCMS_EVENT_LOG.TIMESTAMP>=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 00:00:01', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.TIMESTAMP<=TO_TIMESTAMP(TO_CHAR(SYSDATE-1, 'DD-MM-YYYY') || ' 23:59:59', 'DD-MM-YYYY HH24:MI:SS')
AND UCMS_EVENT_LOG.USER_ID LIKE 'SCP-AGENT1%'
AND UCMS_EVENT_LOG.EVENT_TYPE_ID LIKE '2%'
AND UCMS_EVENT_LOG.ENTITY_TYPE_ID LIKE 'ucms_imported_cards%';
As you see we forced the session to use a huge RBS created for the purpose, but strangely after a long while the query fails with a RBS too small failure due to another RBS, not the one specified.
Is there any chance the UNION or any other component of the query is implicitly opening a new transaction with a different RBS associated?
Any chance to force the same RBS specified explicitly?
Thanks!
Mike

albertone wrote:
but strangely after a long while the query fails with a RBS too small failure due to another RBS, not the one specified.You misunderstand snapshot too old. It can be caused by other sessions same as by your session. Assume AFTER your session issued select some other session modified one (or more) tables ucms_batches, ucms_cards, UCMS_EVENT_LOG and committed changes. By the time your select reaches to fetch rows modified by that other session rollback extents in rollback segment used by that other session were reused. You will get snapshot too old. Bottom line - all sessions modifying table(s) used by your select must use rollback segments large enough so they are not overwritten before corresponding rows are needed by your select.
SY.

Rollback segment is filling up during creation of the database

Hi
The Rollback segment is showing around 520mb immediately after
creation of the database after following the wizard provided in
the enterprise manager of oracle. What might be the reason. How
to reduce it. Could any one give me a solution for this matter.
Thanks in Advance.

I tried creating the password file using the following command:
orapwd file=/home/oracle/product/9.2.0/dbs/orapwHR.ora
password=HR entries=5
and got the same error:
ORA-01501 Create Database failed.
ORA-01990 -ERROR opening password file '/home/oracle/product/9.2.0/dbs/orapw'
ORA-27037 Unable to obtain file status.
Linux error: 2: No such file or directory.
Additional information: 3.
Does anybody know how to fix this problem?
Thanks,
Katya

How to get the size of rollback segments

Hi,
on which oracle table can I see which are the rollback segments and its own size?
Thanks!

doc questions like this one are best answered by querying the view DICT which is present in every release of Oracle (and which you of course -again- fail to mention)
Sybrand Bakker
Senior Oracle DBA

Trying to understand rollback segments - offline tblspaces for backup

Using Oracle 8i, on Windows platform - The question - receive an error ORA-01556 when performing a
sql "ALTER TABLESPACE MY_TBS_LT OFFLINE IMMEDIATE";
=============================================
First off I created a tablespace and table on an 8i database.
create tablespace my_tbs_lt_tbs_lt
datafile '&&2\oradata\&&1\my_tbs_lt_guitest1.dbf'
size 10M
AUTOEXTEND ON NEXT 1280k EXTENT MANAGEMENT LOCAL UNIFORM SIZE 128K; <===== Is this right for use with rollback segments?
CREATE ROLLBACK SEGMENT rbgui1t2 STORAGE(INITIAL 50K NEXT 250K)
tablespace my_tbs_lt;
CREATE ROLLBACK SEGMENT rbgui2t2 STORAGE(INITIAL 50K NEXT 250K)
tablespace my_tbs_lt;
CREATE ROLLBACK SEGMENT rbgui3t2 STORAGE(INITIAL 50K NEXT 250K)
tablespace my_tbs_lt;
CREATE ROLLBACK SEGMENT rbgui4t2 STORAGE(INITIAL 50K NEXT 250K)
tablespace my_tbs_lt;
-- Bring new rollback segments online
ALTER ROLLBACK SEGMENT rbgui1t2 ONLINE;
ALTER ROLLBACK SEGMENT rbgui2t2 ONLINE;
ALTER ROLLBACK SEGMENT rbgui3t2 ONLINE;
ALTER ROLLBACK SEGMENT rbgui4t2 ONLINE;
CREATE TABLE guitester.guitester_t2
( employee_id NUMBER(6)
, first_name VARCHAR2(20)
, last_name VARCHAR2(25)
CONSTRAINT emp_last_name_nn_demo NOT NULL
, email VARCHAR2(25)
CONSTRAINT emp_email_nn_demo NOT NULL
, phone_number VARCHAR2(20)
, hire_date DATE DEFAULT SYSDATE
CONSTRAINT emp_hire_date_nn_demo NOT NULL
, job_id VARCHAR2(10)
CONSTRAINT emp_job_nn_demo NOT NULL
, salary NUMBER(8,2)
CONSTRAINT emp_salary_nn_demo NOT NULL
, commission_pct NUMBER(2,2)
, manager_id NUMBER(6)
, department_id NUMBER(4)
, dn VARCHAR2(300)
, CONSTRAINT emp_salary_min_demo
CHECK (salary > 0)
tablespace my_tbs_lt;
=======================================
I changed the initSID.ora file to have
Rollback_segments=( rbgui1t2, rbgui2t2, rbgui3t2, rbgui4t2)
=======================================
restarted everything
========================================
did a backup of the tablespace my_tbs_lt;
========================================
added some data to the table in the tablespace
========================================
ran a restore/recover - Get the error
========================================
It makes sense that I get the error because it is the tablespace that I have been working with, adding data. Is my logic correct? How does one restore a tablespace if it has rollback segments active? Can someone look to make sure I am declaring the rollback segments appropriately?

Thank you for the link - very helpful.
So would a more appropriate scheme be:
Create a tablespace
Create rollback segments
Put them online
enter their names in the ROLLBACK_SEGMENTS= segment(s)
I havent read everything, so you may say go look at the link again, but a second question. If you are managing the extent locally, does it not use a rollback segments, or is it using system, or is it actually creating rollback segments for itself within the context of the local management?
In my above scenario, I would have to take my rollback segment offline as well as the tablespace.

Rollback Segments

Hello all,
I am hoping someone can help me. I have a dev and prod
instance, with identical rollback segment specs. The problem I
have is that I am running out of space on one of my instances
(dev). The prod instances rbs's are all the same size while the
dev instance rbs's are all over the place. One rbs (in dev) may
be at 10mb and another at 800. I don't know why the size
doesn't reduce after I issue a commit. I think the problem is
that the rbs's for both instances are public and one set of
rbs's is only being used. Can any offer any suggestions? Thank
you!

I would like to suggest 2 things :
1) make all rollback segments to same size
2) set optimal storage parameter of rollback segment.

Rollback segment error

Hello experts,
My problem is as follows:
I need to perform a large transaction on one of my tables in my
database. I have to delete a large number of records using a
command as follows:
Delete from mytable where ordernumber like '2000%';
Each time i launch this command i have the following error:
ERROR at line 1:
ORA-01562: failed to extend rollback segment (id = 3)
ORA-01628: max # extents (30) reached for rollback segment R03
I know that i have a problem with my rollback segment. I have
thus created a large rollback segment so that my transaction can
use it.
I don't know how to tell my transaction use the large rollback
segment that i created.
(i know there is a command called set transation user rollback
segment large_rs1, i have tried it on sqlplus. it gives me
error: ORA-01453: SET TRANSACTION must be first statement of
transaction)
Please help
thanks in advance for a reply
Kind regards
Yogeeraj

First, you have to create a bigger rollback segment (i.e. RBBIG).
Then, before each query, you must type:
set transaction use rollback segment rbbig;
This will force the use of the specified rollback segment.
Hope this helps.

Is "SET TRANSACTION USE ROLLBACK SEGMENT" only a hint

I have two users, one makes some inserts in a table.
The other makes a select which visits many rows.
I have a big rollback-segment.
To ensure, both users use this rollback-segment I created a logon-trigger:
CREATE OR REPLACE TRIGGER a_logon AFTER LOGON
ON DATABASE
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BEGIN
SET TRANSACTION USE ROLLBACK SEGMENT rbs_big;
END;
But I still get "snapshot to old" messages from the select, which contains the name off an other rollback-segment in the message.
The trigger really fires, i tested it by adding an insert-statement to a log-table.
What`s wrong ?

The set transaction use rollback segment lasts only until you commit or rollback first time and all other transactions in that session will not be forced to that rbs anymore. Other possible solution could be that other users are accessing same tables / updating them so those sessions can't keep the read consistent image available anymore for your sessions.

R0 Rollback Segment in Import of 10gR2 into 11gR2 Database

I have a new install of Oracle Database Server Enterprise Edition 11.2.0.3.6 on AIX 7.1.
I used the DBCA to create two databases and used export datapump and import datapump to upgrade two 10gR2 database to 11gR2.
One of the import logs includes the following messages:
Processing object type DATABASE_EXPORT/ROLLBACK_SEGMENT
ORA-39083: Object type ROLLBACK_SEGMENT failed to create with error:
ORA-02221: invalid MAXEXTENTS storage option value
Failing sql is:
CREATE ROLLBACK SEGMENT "R0" TABLESPACE "SYSTEM" STORAGE(INITIAL 131072 NEXT 131072 MINEXTENTS 2 MAXEXTENTS 2147483645)
I verified that the source database has R0 with maxextents of 2147483645.
I can copy and modify the CREATE ROLLBACK statement and lower the value assigned to MAXEXTENTS, or use MAXEXTENTS UNLIMITED, then run the command in the target database.
In light of the fact that the DBCA did not create R0 in my two 11gR2 databases, I want to know if I still need to create R0 in the one that showed the error in the import log. Has anyone else noticed the disappearance of R0?
Here are the rollback segments that exist in the 11gR2 database at this time:
SQL> Select SEGMENT_NAME, OWNER, TABLESPACE_NAME, INITIAL_EXTENT, NEXT_EXTENT, MIN_EXTENTS, MAX_EXTENTS, PCT_INCREASE, STATUS
from SYS.DBA_ROLLBACK_SEGS;
SEGMENT_NAME OWNER TABLESPACE_NAME INITIAL_EXTENT NEXT_EXTENT MIN_EXTENTS MAX_EXTENTS PCT_INCREASE STATUS
SYSTEM SYS SYSTEM 114688 57344 1 32765 ONLINE
_SYSSMU1_3638931391$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU2_3033359625$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU3_2670780772$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU4_286801445$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU5_1738828719$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU6_3548494004$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU7_700714424$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU8_2755301871$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU9_2087597455$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
_SYSSMU10_3267518184$ PUBLIC UNDOTBS1 131072 65536 2 32765 ONLINE
11 rows selected.
Thanks,
Bill

Srini,
Both the 10gR2 and 11gR2 versions of the database are using automatic undo management.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
SQL> show parameter undo
NAME TYPE VALUE
_undo_autotune boolean TRUE
undo_management string AUTO
undo_retention integer 14400
undo_tablespace string UNDOTBS1
SQL>
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> show parameter undo
NAME TYPE VALUE
undo_management string AUTO
undo_retention integer 14400
undo_tablespace string UNDOTBS1
SQL>
Do you know anything about Oracle no longer automatically creating R0 in 11gR2?
Thanks,
Bill

How to check/find the size of current ROLLBACK segment in oracle 10g

How to check/find the size of current ROLLBACK segment in oracle 10g ? Kindly help

A rollback segment name like "_SYSSMU231$" is used when you have Automatic Undo Management enabled.
The only relevant parameters are :
1. UNDO_MANAGEMENT=AUTO
2. UNDO_RETENTION=n minutes ==> this is what everyone should be interested in
3. The sizes of the Undo Tablespace datafiles and whether AUTOEXTEND is ON or OFF
No one should be interested in the size of a single undo segment when Automatic Undo Management is enabled.
Possible causes of ORA-01555 errors in Automatic Undo Management
a. UNDO_RETENTION is too low
b. Undo tablespace is too small
Hemant K Chitale

Materialized view refresh and rollback segment

Hi all,
maybe this is a dumb question but:
We use a few materialized views (partitioned, on prebult tables) in our DB.
The refresh method used is complete.
Every refresh clears old data et the very beginning and leaves the table empty until new data is commited (can take up to 2 hrs). But what is use of specifying the rollback segment than?
I would like to change this behaviour to keep the old data to the very moment of replacing with new one.
Is there a way?
Thanks a lot
Petr

Hi all,
maybe this is a dumb question but:
We use a few materialized views (partitioned, on prebult tables) in our DB.
The refresh method used is complete.
Every refresh clears old data et the very beginning and leaves the table empty until new data is commited (can take up to 2 hrs). But what is use of specifying the rollback segment than?
I would like to change this behaviour to keep the old data to the very moment of replacing with new one.
Is there a way?
Thanks a lot
Petr Oracle will truncate the MV and then effectively insert as select to populate your MV. In doing so
Oracle needs to keep a read consistent view of the select it is executing. Here clearly you might consider specifying a specific rbs.
Have you considered fast refresh or is this not a candidate? At least with fast refresh you won't have to compeletly rebuild the mv each time and it will be considerably faster.
steve

OPTIMAL size for rollback segment in Oracle 8i

In our Database we have 13 Rollback segments & total size of all rollback segments is 33gb.
Used % it is showing 99.84%.
each rollback segment having near around 4gb of size.
I am in confusion to set OPTIMAL value for each rollback
segment.
can any one help me out reg this.
My roll back seg statistics are as fallows:
SEGMENT_NAME TABLESPACE_NAME WAITS SHRINKS WRAPS STATUS
R00 SYSTEM 0 0 12 ONLINE
RBS0 RBS 0 0 19 ONLINE
RBS01 RBS 0 0 16 ONLINE
RBS02 RBS 1 0 12 ONLINE
RBS03 RBS 0 0 11 ONLINE
RBS04 RBS 0 0 21 ONLINE
RBS05 RBS 1 0 22 ONLINE
RBS06 RBS 0 0 16 ONLINE
RBS07 RBS 0 0 15 ONLINE
RBS08 RBS 0 0 12 ONLINE
RBS09 RBS 1 0 19 ONLINE
SEGMENT_NAME TABLESPACE_NAME WAITS SHRINKS WRAPS STATUS
RBS12 RBS 0 0 13 ONLINE
RBS13 RBS 0 0 18 ONLINE
SYSTEM SYSTEM 0 0 0 ONLINE

Aman,
Definitely that would be a great approach to share the knowledge; but right now my notes are still in the shape of notes only; i have'nt tested them. I simply read forum and asktom and whenever i found good lines i copy and paste them and whenever i found the similar question in the forum i paste / repharase there in my own language and understanding (because till then i have tested and learnt them very well.)
Although i am highly obliged by your suggestation; let me that much knowledgable; so that i may run my own blog...!
Regards
Girish Sharma

One sytem rollback segment though AUM

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