Max rollback segments in 10g

Hi,
What determines the max rollback segments in 10g? I know that the max rollback segments is min(ceil(transactions/transactions_per_rollback_segments),max_rollback_segments) in 9i.
Thanks

In Oracle 10g you should use automatic undo management so that you don't need to care about number of rollback segments but let Oracle manage automatically the number of undo segments.

Similar Messages

Rollback segments & UNDO (8i to 10g migration)

Hello all,
I need to migrate a database from 8.1.0.7 (server a) to 10.1.0.2 (server b) on HPUX and I am going through pre-tasks for IMP.
On 8i:
Tablespace name: RBS
4 Rollback segments on RBS tablespace
1 System Rollback segment, on SYSTEM tablespace
On 10g:
Pre-created UNDO01 tablespace
4 Undo on UNDO01 tablespace
1 Undo on SYSTEM tablespace
My question is, can i run IMP full=y as is?
Or should I pre-create the Rollback Tablespace & rollback segments on 10g also?
If this is the case, what should my init.ora parameter show?
#rollback segments
rollback_segments = (acbr01,acdbr02,acdbr03,acdbr04)
#undo
undo_segments
undo_management = auto
undo_tablespace = undo01
Thanks!

Hi..
You can use IMP full=y, there is no need to create rollback segments in 10g. In init file mention you need to mention
#undo
undo_segments
undo_management = auto
undo_tablespace = undo01
The import utility will use UNDO tablespace, so keep monitoring it.
Anand

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

Not able to see rollback segment in oracle 10g

hi all
I created rollback segment by using command
CREATE ROLLBACK SEGMENT rs1 TABLESPACE rbs_ts
and made it online but not able to see
segment name by using
select * from dba_rollback_segs
Please help me
Ragards
Edited by: 174313 on Dec 1, 2008 3:19 PM

You can start with the following links in 10g documentation.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/mgmt_db.htm#sthref2230
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/logical.htm#CHDGJJEJ
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/logical.htm#CNCPT305

Ora-01555, snapshot too old: rollback segment number 2 with name "_SYSSMU1

Hi,
Oracle 10g,
Im getting this error during execution of a query
Autoextend is ON for the undo datafile
There is 6 GB free space in the undo tablespace
Earlier the value for undo_retention was 18000.
I reset it using alter system set command to 25000.
But it still gives the same error
Please suggest on what could be the issue

Hi,
I got the same error twice since 2 weeks.
The DB size is 1.4TB and the TBS are as follows:
SQL> SELECT tablespace_name, retention FROM dba_tablespaces;
TABLESPACE_NAME RETENTION
SYSTEM NOT APPLY
SYSAUX NOT APPLY
PSAPUNDO NOGUARANTEE
PSAPTEMP NOT APPLY
PSAPSR3 NOT APPLY
PSAPSR3702 NOT APPLY
PSAPSR3USR NOT APPLY
7 rows selected.
the PSAUNDO tbs is 12GB.
SQL> select max(maxqueryLEN) FROM V$UNDOSTAT;
MAX(MAXQUERYLEN)
40672
SQL> show parameter undo;
NAME TYPE VALUE
inmemory_undo boolean FALSE
undo_management string AUTO
undo_retention integer 900
undo_tablespace string PSAPUNDO
Is undo_retention used only for flashback or it will improve Query, update and delete statements?
What will be the appropriate size for undo_retention?
Note that currently we are doing archiving and it is taking much of the resources in terms of rollback segments.
Please advise
Thanks,
Gavisht

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.

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

Rollback segment number not shown with name " not shown " too small

Hi,
we have a table TABLE1 with a BLOB field FIELD1 on a Oracle 10g database. Today we found out that there is one record in that table that make problems. if we try to read the BLOB data from that record, Oracle shows the error:
ORA-01555: snapshot too old: rollback segment number with name "" too small
The strange thing about it, that the message shows neither the segment number nor the segment's name. Like it has lost the reference to it.
Could you help please.
Notes:
The TABLE1 and the BLOB data are really not big.
The UNDO tablespace is 2Gb big and just 1% used.
Thank you very much
Igor

Out-of-row LOB undo is maintained in the LOB segment. So the UNDO tablespace and undo retention is not associated with most LOB ORA-1555 issues. Instead the LOB column is created using either PCT_VERSION or RETENTION to manage how much space within blocks or time transpires before the LOB undo is overwritten. In environments with high updates, deletes on rows including LOBs, the chances of ORA-1555 on LOB undo is very high.
Source:http://blogs.oracle.com/db/entry/troubleshooting_ora_1555
In the above link you will get plenty of good metalink notes to understand and solve the issue.
There is no undo segment name in the error message means this error has no relation with undo tablespace/parameter/segment. This might mean that your LOB table is corrupted. Can you drop and recreate/re-populate this table and try again ?
Srini Chavali @ Another "snapshot too old: rollback segment number with name "" too small"
Regards
Girish Sharma

ORA01555"snapshot too old:rollback segment num %s with name "%s" to small

Hi All
i have and 11gR1(11.1.0.6) DB source instance in wich i have i a partitioned table of 1TB size.
I want to IMPDP this table using NETWORK_LINK in a 11gR2(11.2.0.3) destination RAC instance.
when a try to import a get the following error message
ORA 01555 "snapshot too old: rollback segment number %s with name \"%s\" too small"
UNDO_RETENTION=130000
UNDOTBS1=300GB
UNDOTBS2=220GB
i have searche dhte metalink docs but did not find any solution.
is there any hint or document to follow?
thanks in advance
Soni

Hi,
Stopping the loading may work - it there is no other activity going on then you should be OK.
If you want to guarantee the undo doesn't get overwritten for the length of the export you can run switch on guarantee undo retention for the undo tablespace - by default it is just a target not a guarantee - see this link for more details:
http://www.oracle-base.com/articles/10g/space-object-transaction-management-10g.php
Regards,
Harry

Rollback Segment: dedicate it to a given session ?

Dear Experts,
A job is performing nightly deletion on some data.
I created a "big" RBS for it and perform the following:
SET TRANSACTION USE ROLLBACK SEGMENT RBS01;
DELETE FROM TABLE1 WHERE (...);
COMMIT;
Is it possible that only this transaction uses RBS01 i.e. having RBS01 dedicated to my transaction untill the COMMIT is done ?
Thanks for any advice.
Best Regards,
Guillaume.

I've got a complementary question.
As I don't want the clean-up job to "eat" all my CPU I'd need to limit the CPU allocated to this task. I can see in Profile a CPU_PER_SESSION parameter but I'm looking for a way to set a max % of the CPU usage and not a max in duration. Any trick ?
Thanks for your support.
BR,
Guillau

ORA-01581: attempt to use rollback segment...

We've started getting "ORA-01581: attempt to use rollback segment (31) new extent (3) which is being allocated" messages in our production database over the last couple of days. Of course, each time we get these the rollback segment number is different, and we are getting these randomly from different applications that connect to the same database. We are using automatic undo management, so the rollback segments are not really under our control. The action in the Oracle docs for this error message doesn't give any specific actions that we should take, but we continue to get these.
We started to get these about the same time as we ran out of available sessions on the database (sessions = 1500 and we had 1500 open sessions). Could these be related? Could there be some open session that may be causing the rollback segment issue? Would a restart of the database fix this? Of course the max sessions issue was cleaned up two days ago but the rollback segment issue is a lingering problem.
Any help would be appreciated. We couldn't find anything for this online and Oracle hasn't responded to our service request yet.
Thanks,
Bobby

As I understand it, you can not explicitly set the size for the undo segments in automatic undo management mode. From the Concepts guide:
"In automatic undo management mode, the system controls exclusively the assignment of transactions to undo segments, and controls space allocation for undo segments."
It looks like we are also using the default storage options that are set when the UNDO tablespace was created. Here is the DDL used to create this tablespace:
CREATE SMALLFILE UNDO TABLESPACE "UNDOTBS" DATAFILE '/alpha/oradata/prod01/undotbs01.dbf' SIZE 750M REUSE AUTOEXTEND ON NEXT 25600K MAXSIZE 2000M , '/alpha/oradata/prod01/undotbs03.dbf' SIZE 2000M REUSE AUTOEXTEND ON NEXT 51200K MAXSIZE 2000M , '/alpha/oradata/prod01/undotbs04.dbf' SIZE 2000M REUSE AUTOEXTEND ON NEXT 104K MAXSIZE 2000M , '/alpha/oradata/prod01/undotbs02.dbf' SIZE 2000M REUSE AUTOEXTEND ON NEXT 25600K MAXSIZE 2000M

Error:cannot use system rollback segment for non-system tablespace

Hi,
I have created a oracle database 10.2.0 on fedora 9 system. I have created a user and assigned the default tablespace SATYA and given the permissions. But when I create a table in the user I am getting the following error.
Can anyone help me in rectifying this error.
ORA-01552: cannot use system rollback segment for non-system tablespace 'SATYA'
thankyou
satya

Undo management is either AUTO or Manual, no local
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/undo.htm#sthref1469
Since you are using 10g, you are recommended to use Auto undo management
If you still plan to use manual undo management, make sure you have other non-system rollback segment in place.

Rollback segment error ORA-1628

Hellow
Currently we are working on Oracle 8i database.The database contain spatial data around 10GB.We have a tablespace RBS containing 4 rollback segments. The issue is whenever we try to insert spatial data we get this error message (in the alert file)
ORA-1628: max # extents 121 reached for rollback segment R01
Failure to extend rollback segment 2 because of 1628 condition
FULL status of rollback segment 2 cleared.
I extended the size of RBS tablespace by adding another datafile, but still it doesn't help.
Also i found that RBS tablespace is marked as PERMANENT...it means the rollback data does not get flushed out periodically?Also Should this tablespace be temporary? How can i counter this problem?
Regards
Sam

Hi,
01628, 00000, "max # extents (%s) reached for rollback segment %s"
// *Cause: An attempt was made to extend a rollback segment that was
// already at the MAXEXTENTS value.
// *Action: If the value of the MAXEXTENTS storage parameter is less than
// the maximum allowed by the system, raise this value. => Alter your RBS and allow more than 121 extents to be created in this RBS.
Also i found that RBS tablespace is marked as PERMANENT.Yes, it's normal.
..it means the rollback data does not get flushed out periodically?No
Also Should this tablespace be temporary? No, this can't be
How can i counter this problem?Free advise: RTFM about Rollback Segments! Start here (8i doc) or read the Concepts book.
Regards,
Yoann.

DAL Exception: ORA-01562: failed to extend rollback segment number 4

Hi,
in our application log, we got sometimes an error ORA-01562: failed to extend rollback segment number 4 and the application hangs and some transactions are blocked. checking the aler database file, we don't found this error but it's appearing often in our system.
would you lease advise what to do to avaoid this error, or is there a script to find oracle SQl where using too much rollback segment.
My configuration is : Oracle 10g r2 in linux SUSE.
thank you
Lucienot.

Hi,
Please refer MOS tech note *ORA-1562 and ORA-1650 Unable to Extend Rollback Segment [ID 1066542.6]*
thanks,
X A H E E R

Rollback segment in locally manage tablespace

Is it possible to create rollback segment in
locally manage tablespace in oracle 8i(8.1.6)
kuljeet pal singh

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

Max rollback segments in 10g

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