Roll back segments - Oracle 8i

Hi :
i am running my production db on 8i and i am noticing that my roll back tablespace is running out of space. I want to add a datafile to the tablespace. Can i do this while keeping the tablespace online ?
- BMP

In Oracle 9i Database and below, you can issue the query
SELECT USED_UREC
FROM V$TRANSACTION;
which returns the number of undo records used by the current transaction, and if executed repeatedly, will show continuously reduced values because the rollback process will release the undo records as it progresses. You can then calculate the rate by taking snapshots for an interval and then extrapolate the result to estimate the finishing time.
~ Madrid

Similar Messages

Managing Undo tablespace & roll back segments

Hi,
I have oracle 9.1 version and have created 5g undo tablespace apart from 20m rbs tablespace for 15 rollback segments. But it is seen that whenever i give UNDO_MANAGEMENT=AUTO then rollback segments are created using undo tablespace and not allowing rollback segment in rbs tablespace ONLINE. In the reverse happens whenever I give UNDO_MANAGEMENT=MANUAL , the rollback segments in the rbs tablespace gets focus and roll back segments in the Undo tablespace goes offline. Is there anything that I can do so that both undo tablespace and redo segments in the rbs tablespace gets working together so as to minimize the undo contention. Moreover, any query given takes long time when select query given with || in the subquery.
Please suggest the tuning need to do?

brain_heart wrote:
Hi,
I have oracle 9.1 version and have created 5g undo tablespace apart from 20m rbs tablespace for 15 rollback segments. But it is seen that whenever i give UNDO_MANAGEMENT=AUTO then rollback segments are created using undo tablespace and not allowing rollback segment in rbs tablespace ONLINE. In the reverse happens whenever I give UNDO_MANAGEMENT=MANUAL , the rollback segments in the rbs tablespace gets focus and roll back segments in the Undo tablespace goes offline. Is there anything that I can do so that both undo tablespace and redo segments in the rbs tablespace gets working together so as to minimize the undo contention.No that's the way it would work, you can either use the automatic undo or the manual one.not both. And its better to stick with the automatic one IMHO. Have a read of this link to understand more about undo.
http://download.oracle.com/docs/cd/B10501_01/server.920/a96521/undo.htm#8888
HTH
Aman....

How to remove a roll back segment file in 8.1.7

Hi,
How to remove a roll back segment file in 8.1.7 ?
My RBS tablespace has two datafiles, how can I delete one of them ?
Thank you.

You would
a. Create a new tablespace to hold rollback segments
b. Create rollback segments in the new tablespace
c. Bring the new rollback segments online and the old rollback segments offline
d. Wait for all the old rollback segments to go offline (they'd be in PENDING OFFLINE if there are active transactions)
d. Drop the old rollback segments
e. Drop the old rollback tablespace -- after confirming that it has NO active rollback segments and NO OTHER segments at all
f. Modify your init.ora to specify the new rollback segments in the "rollback_segments=" parameter
If you want to switch back to the old tablespace name and segment names, you'd do steps a to e and then run them again to recreate the old tablespace name (with 1 datafile, excluding the one you want to drop) and segment names.

Dump roll back segment too small

Hii All,
From last week i am getting this dump in my production system.
Database error text........: "ORA-01555: snapshot too old: rollback segment
number 20 with name "PRS_18" too small#"
Internal call code.........: "[RSQL/FTCH/MKPF ]"
What should i do to avoid this dump.
Regards,
Viren.

HI Rana,
When you have "ora-01555: snapshot too old (rollback segment _ too small)", it usually means failure due to the lack of rollback space. The failure indicates read consistency error, as your active transaction overwrites existing, uncommitted transaction, which implies that the system change number SCN in the block is newer than the SCN at the start of the transaction. The read consistency image of new data can therefore not be created. This can happen when large transactions are being written where there is not enough tablespace for the rollback segments to expand or when the rbs has reached its "MAXEXTENTS".
Solution is to either add new roll back segment or extend the size of the existing ones.To extend the size of existing ones, increase both the values of their MINEXTENTS and OPTIMAL parameters with ALTER ROLLBACK SEGMENT statement or create additional ones.
Thanks
Prince Jose

Roll back segment usage

Hi, i have a script which will report usage of roll back segments in my db, it gives me rb name #, username, and the table/schema.
I want to have a script which i can maybe enter a variable into (say, concurrent program id) and then have a list of the rbs its using and anything else that may be using the same ?
Anyone help?
regards

doh! i meant to after i posted but got sidetracked :-)
col "User" form a10
col "Table Name" form a10
col "Rollback segment name" form a21
select /*+ RULE */
rn.usn "Rollback segment number",
rn.name "Rollback segment name",
sess.schemaname "User",
sess.sid "sess",
o.name "Table Name"
from
v$rollname rn,
v$session sess,
sys.obj$ o,
v$lock lck1,
v$transaction t
where
sess.taddr = t.addr
and lck1.sid = sess.sid
and lck1.id1 = o.obj#
and lck1.type = 'TM'
and t.xidusn = rn.usn

Roll back segments into READ-ONLY Mode

To bring an v8 database into READ-ONLY Mode do we need to put the Roll back tablespace RBS also into READ-ONLY Mode?

You can put database in READ ONLY mode in Oracle 8i
READ ONLY / READ WRITE Example
The first statement below opens the database in read-only mode.
The second statement returns the database to read-write mode and clears the online redo logs:
ALTER DATABASE OPEN READ ONLY;
ALTER DATABASE OPEN READ WRITE RESETLOGS;---
http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a85397/stateme3.htm#2048938

Roll back segment

Thanks for advance.
I am learing Oracle8 database management. I am wondering if I create 5 roll back seg but only bring one of them online when starting up instance. Are the left four can be brought
online automaticly when the first seg is full?
Or it is a must to wake all roll back seg when you start the instance?
Thanks again.

You can edit initorcl.ora to increase "transactions" parameter.
The formula of 'rollback segments goes online on restart' = transactions / transactions_per_rollback_segment
RDBMS does not remember what rollback segment was online before restart.

Transaction doesn't roll back to Oracle

          Hello, I would like to ask does webloogic support transaction controlled by client
          which is out of container? My case is that i use UserTransaction in the client
          application(not within bean). Bean methods (CMP) are invoked between the UserTransaction.begin()
          and UserTransaction.rollback(). However, row are inserted into database and the
          rollback fail at the end.
          Any ideas?
          Thanks


          Joseph Weinstein <[email protected]> wrote:
          >
          >
          >Leo Choi wrote:
          >
          >> Hello, I would like to ask does webloogic support transaction controlled
          >by client
          >> which is out of container? My case is that i use UserTransaction in
          >the client
          >> application(not within bean). Bean methods (CMP) are invoked between
          >the UserTransaction.begin()
          >> and UserTransaction.rollback(). However, row are inserted into database
          >and the
          >> rollback fail at the end.
          >>
          >> Any ideas?
          >
          >I assume you get the UserTransaction from Weblogic. How are the bean's
          >transactional
          >behavior specified? TX-SUPPORTS, TX-REQUIRES, etc? What version of weblogic
          >are you running? To answer your question in the general, if the beans
          >are involved in the
          >transaction, then all DBMS updates they do should roll back if you roll
          >back the UserTransaction.
          >If, however, the beans are not part of the tx, such as if they are marked
          >as TX-REQUIRES-NEW,
          >then each invoke of the bean will start it's own tx during the invoke,
          >and commit it separately
          >at each method, so any later rollback of the bigger tx won't involve
          >any of the little
          >already-committed
          >EJB tx's...
          >Joe
          >
          >>
          >>
          >> Thanks
          >
          Thanks for you reply. I am new to transaction.
          The version i am using is 7.0. I get the UserTransaction by ctx.lookup("UserTransaciton......)
          where ctx is the InitialContext.
          You are right, i found that the transaction is committed at each method.
          If i call setRollBackOnly() before calling the bean method, the transaction
          cannot committed.
          But it is meaningless to me since the transaction should be able to roll
          back at any points before the UserTansaction.commit();
          TX-SUPPORTS, TX_REQUIRES....are you talking about the deployment descriptor?
          I have check the deployment descriptor, the transaction attr is Required.
          The rollback() method doesnt work. Are there any things missing?
          Thanks

Short dump - reading from roll back segment

Hi All,
I am getting this short dump for few loads.The error is :
"(FUNCTION)", or declared in the procedure's RAISING clause.
To prevent the exception, note the following:
Database error text........: "ORA-01555: snapshot too old: rollback segment
number 108 with name "PRS_77" too small"
Did any body got this eror:If so,could you please explain why it's comming and how to fix this permanently?
Thanks
Manish

The DBA probably needs to increase the size of the Rollback segment and/or tablespace.
Google the error message for more info. Here's a link to Jonathan Lewis's (well known Oracle author)site.
http://www.dba-oracle.com/t_ora_01555_snapshot_old.htm
Added the link to J Lewis site.
Message was edited by:
        Pizzaman

Set transaction use roll back segmet

Hi all:
I have lot of packages with the statement set transaction use roll back segment RBS_BIG.I am working on upgrade project and using undo tablespaces.
Is there a quick way to grep the this statement from all the packages and remove off.Does the presence of this statement in packages of new database cause compilation errors ?
Thanks,
Ganesh

Hi,
Set init.ora parameter as follows and restart database. All SET TRANSACTION USE ROLLBACK SEGMENT statements will have no effect and ignored.
UNDO_SUPPRESS_ERRORS=TRUE
You may use ALTER SYSTEM rather than restart db. If your database use spfile.ora, you have to execute:
ALTER SYSTEM SET UNDO_SUPPRESS_ERRORS=TRUE SCOPE=BOTH;
Best regards,
Dima

Set transaction use roll back

Hi all:
I have lot of packages with the statement set transaction use roll back segment RBS_BIG.I am working on upgrade project and using undo tablespaces.
Is there a quick way to grep the this statement from all the packages and remove off.Does the presence of this statement in packages of new database cause compilation errors ?
Thanks,
Ganesh

The set transaction use rollback segment <rbsegment> is ignored in 10g. In 9i databases this could cause errors when using automatic undo management. For your 9i databases you can suppress the errors by setting UNDO_SUPPRESS_ERRORS=true.

Oracle 10g Paremeter to Auto Roll Back uncommited transanctions

Hi all
In SME Segment - People donot affort having Oracle Dba and at the same time less experienced persons keep making their own tests
Situation goes as under :-
a) Oracle 10g Windows 2003 64 Bit version on Branded HP Server with 8GB Ram having around 100 simultaneous users
b) User A on Machine A fires command say
Table Iledg has inventory data say around 2 Million records
Update iledg set gwt = netwt + corewt where vrdate >= ??? and vrdate <= ??
Records get updates - But user A does either of the following
i) Does not give commit
ii) Preses Ctl + Alt + Del
iii) Switches off the Computer
Problem
All other users get hanged for their Transanctions relating to table Iledg. EDP person is not able identify the culprit i.e User A
We have already tried - that if we kill the session of User A , position becomes OK
Solution wanted for
a) Set some Oracle Parameter which automatically rolls back un committed transnactions for say 5 Minutes
b) Oracle automatically kills those sessions who have un commited transanctions for more than say 5 minutes.
Because in SME Segment - It is very difficult to ask the users to fire some very technical commands to find out the culprit and to kill their sessions. At the same time we can not start the server again and again.
Suresh Bansal

Thanks for the reply.
We were also very sure about Oracle 10g beharviour but it actually does not happen in abnormal disconnections.
We tested this way
a) Table Iledg has inventory data say around 2 Million records
Machine A fires command say
Update iledg set gwt = netwt + corewt where vrdate >= ??? and vrdate <= ??
Oracle Results -> ?? rows updated ->Did not gave commit command ->Intentionally to test it switched off the machine without Exiting from
SQL*Plus
then on Machine B)
Again tried to
Update iledg set gwt = netwt + corewt where vrdate >= ??? and vrdate <= ??
Session of Machine A is not killed by Oracle 10g and is blocking the Transanction of Machine B which is very unfortunate as we thought Oracle 10g must have killed the session of Machine A when he switched off his Machine. When blocking_session of Machine A is killed ->Position becomes absolutely OK and normal.
This can be tested in just 2 minutes at your end.
Kindly suggest some workable remedy to overcome such abnormal client disconnections. Setting Profile idle time is not the workable solution as we create Oracle Connection at the start of VB6 application and that connection goes on thru out applications for all reports and transanctions.
This kind of problem is not faced in last 6 years over the same forms. But now the client network has grown to say 700 Computers and is creating problems intermittently which is diagnosed properly and terminates the Oracle Connections which sometimes creates these kinds of problems.
Suresh Bansal

Difference between roll back and undo segment.

Hi ,
Oracle 10.2.0.1.0
whats the difference between roll back and undo segemnt ? are they one and same as per changing version of oracle ? please help

Hi,
Both will do the same functionality,but in oracle 9i they made it simplify ,because if u are using rollback segments ,u need to put them online in init.ora and u need to take care space management etc.
so in oracle 9i they introduced undo tablespaces on that u can creage undo segments and space management will be take care by oracle managed files ,so its reduces the burden of dba
Regards,
Simma....

Redo on rolling back a transaction.How?

A transaction will generate redo and rolling back that transaction will generate further redo.
I am a bit confused about rolling back a transaction further generates redo.can any one shed some light on the above statement.
Thankx..

data blocks are protected by redo.
Tables: they are in data blocks
Indices: they are in data blocks
Undo segments: they are in data blocks.
Crash recovery alone would require the rollback to be protected by redo.
Apart from that: a rollback modifies data blocks.
They are protected by redo.
Sybrand Bakker
Senior Oracle DBA

Time taken to roll back a failed transaction

One of our customers has reported that a batch transaction, which takes about 3 hours to complete, failed after 2 hours and took 14/16 hours to roll back.
Is there a rule of thumb guideline available which can predict the time taken to roll back. Does it depend upon time the transaction was running before it failed and the size of roll back data created in rollback segment.
Thanks
Cheema

This is supplement to the original question.
Will there be a significant difference between time taken to roll back in the following two situations :
1) failure is detected by the transaction and an explicit rollback statement is issued by the stored procedure performing the transaction.
2) Connection to oracle is lost and DBA kills the session
Cheema

Roll back segments - Oracle 8i

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