Rollback segment and remote select

It seems that a transaction doing a remote select (I mean a select from one machine to another one via sqlnet) generates some entries in the rollback segment of the remote machine.
Do you know why ? Normally, only transactions modifying data generates info in a rollback.
Thanks for your help

See article
Why does it seem that a select over a db link requires a commit after execution?
http://www.jlcomp.demon.co.uk/faq/dblink_commit.html
HTH -- Mark D Powell --

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Tablespace, Rollback segments and Undo tablespace

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Kishan

Hello Kishan
Yes. Make tablespaces bigger. However, the proper way to do it is optimizing your queries. If you don't have experience with Oracle DB, consult your DBA.
Hope this helps
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One of the DBA's added a large rollback segment which caused the rman backup to abort. The rollback segment was taking offline and it's datafile was taken offline, all went normally no errors. An Application started gettting errors the database and application were taking down and up, no errors on either but the problem was still there. The rbs datafile and RBS were placed back online and the application worked properly. It looks as if Oracle let us take the RBS and datafile offline with active segments in the RBS is this possible?? If so it means you can pull the rug out from under Oracle and it doesn't even complain

Pls check any transactions written in application level,
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Hi guys,
Can you tell difference between Rollabck segments and UNDO Tablespaces.
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but my question still both the rollback abck segments and UNDO tablespaces exists.
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i want to reduce size of rollback segment and utilized this space for other purpose.
This is my stats
Tablespace Name FILE_NAME SIZE IN MB
ROLLBACK /u01/rbsdata/rbs01.dbf 5000
ROLLBACK /u01/rbsdata/rbs02.dbf 5000
ROLLBACK /u01/rbsdata/rbs03.dbf 6000
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SEGMENT_NAME FILE_NAME SIZE
rbs0 /u01/rbsdata/rbs01.dbf 5000
rbs12 /u01/rbsdata/rbs01.dbf 5000
Now Could any one suggest to reduxe size with best performing and not affected my production database.
Thanks
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Hi Chetan,
You can adapt the following script as per your needs. It will search for all rollback segments other than 'SYSTEM' and construct the sql order to reduce the size of each rollback segment.
connect user/*******@test
SET SERVEROUTPUT ON size 50000
SET HEAD OFF FEEDBACK OFF VERIFY OFF
SPOOL D:\shrink.sql
BEGIN
     -- RBS to be shrinked
     FOR toto IN (select Segment_Name from DBA_SEGMENTS
where Segment_Type = 'ROLLBACK'
and segment_name not in 'SYSTEM')
     LOOP
          DBMS_OUTPUT.PUT_LINE('alter rollback segment '||toto.Segment_Name||' '||'shrink to 60M;');
     END LOOP;
END;
SPOOL OFF
SET HEAD ON FEEDBACK ON VERIFY ON
spool d:\shrink.log
select to_char(sysdate, 'dd/mm/yyyy hh24:mi:ss') "Shrinked" from dual;
@D:\shrink.sql
spool off
Exit
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Is there any metric in OEM which does the following...
Am trying to read the document and find the metric which does the following ..not having much luck...
#* Description : Process to monitor and notify DBA about any in-doubt
#* transaction which is holding ROLLBACK Segment and
#* troubling system resources for longer time.
Thank you

Below are more details on what it does...trying to find if any metric in OEM does this...thank you
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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

Rollback segment problem during import

Hello experts,
please help.
I have the following error when importing table data to my
Oracle 8.1.7 database.
IMP-00058: ORACLE error 1562 encountered
ORA-01562: failed to extend rollback segment number 16
ORA-01237: cannot extend datafile 3
kind regards
Yogeeraj

alter the tablespace which contains rollback segments, and
either change the existing datafile (datafile 3) to autoextend
on or resize, or add new datafile in another disk drive which
has more space (it is better to set autoextend on or give it a
larger space).
Hello experts,
please help.
I have the following error when importing table data to my
Oracle 8.1.7 database.
IMP-00058: ORACLE error 1562 encountered
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kind regards
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When to backup the rollback segments?

Does anyone know when do I need to backup the rollback segments and what for? How are they used during restore/recovery?
I'm using RMAN in Oracle 9.2. We have databases with both manual and automatic undo management. Does the undo management type make any difference?
Thanks,
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Does anyone know when do I need to backup the rollback segments and what for? How are they used during restore/recovery?
Your question is a little large to answer but I am going to summary the most important.
The database works with transactions in commit and in not commit mode. While a transaction has not commit , this transaction has not finished. While the transaction has not finished the rollback segments or undo segments are used to store the image of blocks with changes and without changes. That is the method that Oracle uses to ensure that a block is not going to be modified definitevely until the transaction gets commit.
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When you want to recover a database all tablespaces are need excepting the temp tablespace because that tablespace is only needed to carry out sorts and operation likeness.
Does the undo management type make any difference?
if you use rollback segments you have to administer them and the management instead if you work with undo tablespace. If you work with undo tablespace it by itself manage its segments you do not have to worry about.
I think that I have answered your questions if you have any doubt or something like that feel free to follow asking.
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Joel P�rez

Alter rollback segment command giving error.

Hi all ,
i am novice to Oracle 9i i am altering rollback segment but getting following error messages.
ORA-30021: Operation not allowed on Undo Tablespace
ORA-25150:Altering of extent parameters not permitted
(in this i am trying to alter maxextents parameter of rollback segment )

Apparently you are using undo segments, as opposed to rollback segments.
You should use undo segments, and they are located in a separate undo tablespace (see the first error message)
Oracle manages the undo tablespace. You can't do anything about it.
However, Oracle is still using 'rollback segment' and 'undo segment' interchangeably.
Likely, your rollback segment is an undo segment, and you can not change it, nor do you need to.
Sybrand Bakker
Senior Oracle DBA

Error rollback segment - urgent

hi
i have created locally managed tablesspace and in init.ora file i have sent unto management as manual as our application needs to specify rollback segments
when i created rollback segments and attached to a locally managed tablespace i am getting ora-01552 error
i have also speecified names of rollback segment in init.ora file
ERROR at line 1:
ORA-01552: cannot use system rollback segment for non-system tablespace 'ROLLTBLS'
can i not specify a rollback segment to locally managed tablespace
regards
Kedar

the database is in open mode and the undo_management is set to manual. after i created the locally managed tablespace i ran the script for rollback segment refering to one of the above locally managed tablespace
what other checks do i have to make for creating rollback segment.

Rollback segment + oracle 8i

Hi,
I am working in oracle 8i. I am having a doubt in rollback segment. what is the use of optimal parameter in rollback segment and whether its important or not.
Rgds...

This might help:
http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76956/rollbak.htm#586

Oracle9i How to convert from undo tables to rollback segments

Hi,
Anyone try before converting from UNDO management to using rollback segment....What are the procedures for the conversion...
Thank You...

Hi,
Follow these steps to convert from Auto UNDO to Rollback Segs....
1. With the database opened, create a rollback tablespace and then create some rollback segments and bring them online like this
CREATE ROLLBACK SEGMENT RBS1 TABLESPACE RBS;
ALTER ROLLBACK SEGMENT RBS1 ONLINE;
2. Then edit the PFILE and modify these parameters
Add: ROLLBACK_SEGMENTS=(RBS1,RBS2,RBS3....)
Comment: UNDO_MANAGEMENT=AUTO and UNDO_TABLESPACE=UNDOTBS or whatever name you have for your UNDO tablespace.
3. Shutdown the database gracefully(normal).
4. Startup pfile=<Pfile path>
5. Sync these new parameter changes to the SPFILE by recreating the SPFILE.
6. Take a full level 0 backup of your database as the structure has changed.
The next time you start the database, it will use the SPFILE which is same as the PFILE.
Regards.

How to solve about rollback segment fail to extend?

I've a transaction about 50,000 records, then process fail in script. the error code is ORA-01562 FAIL TO EXTEND ROLLBACK SEGMENT = num. I'm use oracle database 7.3.4., form 4.5

It would be better to have several small transactions instead of one huge transaction of 50000 records, like you say. You may use an additional log table to keep the log of how far you've got in processing those 50000 records, and pick up from where you've left in case something goes wrong.
Anyway, one thing that may help would be to use:
alter tablespace your_rbs_tablespace
add datafile ...;
to have more space for your rollback segment(s).
Eventually, you may have a large rollback segment and set transaction use huge_rbs, in order to have your huge transaction use that huge rollback segment.
null

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My production database rollback segments are near to full.
What is the best way to perform tunning ?
Should I go drop roolback segments and recreate ?
Can we drop the SYSTEM rollback segment and recreate ?

Rollback will always show full. As items are commited and written to the database, the space will be re-used, but the high water mark doesn't change. Unless you are getting unable to extend messages, don't worry.

Rollback segment and remote select

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