Is there so call "dedicated" UNDO tablespace in Oracle 9i and higher?

Since one of our applicaions needs to process large amounts of data, we have been using a dedicated rollback segment in order to avoid the "snapshot too old" problem.
Recently our DB upgraded to Oracle 9i and DBA asked us to use "undo" tablespace.
Based the Oracle 9i Doc., it only allows to select ONE undo tablespace at a time.
If so, DBA has to make the only UNDO as large as our Cash large transactions
need(adjust the UNDO_RENTION), which inevitably waste lots of space.
Does Oracle 9i allow to have one dedicated UNDO tablespace for large transactions while another one for regular transactions just like we use the old rollback segments.
Thanks in advance

Why have multiple UNDO tablespaces? You can only use one at a time, and when the other one is not being used, it still consumes storage space.
Spend a little time determining how much undo you need and size undo tablespace and undo retention around those values and you should be able to resolve the problems you are experiencing now.
http://download-east.oracle.com/docs/cd/B10501_01/server.920/a96521/undo.htm#9505

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How to define tablespaces in Oracle 10g and how put tables on tablespaces

Hello,
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Do you know some rules on how to define this?
What I have until now:
1) Put table indexes in separate tablespace
2) Put lobs in separate tablespace and use storage clause when defining the lob column. Not sure how many tablespaces to use, I have tables with millions of lobs and tables with just one lob (with row containing the lob).
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Thank you, Alex.

Long story: I received database and schema creation scripts defined in Oracle 9i. I want to redesign the tablespaces number/storage and also to change the distribution of tables into tablespaces.
As an example I will show how tablespaces are created now. There is one tablespace for indexes BLUE_AUTO_INDX and one for each EXTENT MANAGEMENT of:
- 64K for BLOB , name BLUE_K064_BLOB
- 64K for tables , name K064_NTAB
- 128K for tables, name BLUE_K128_NTAB
- 512K for CLOB , name BLUE_K512_CLOB
- 4M for BLOB , name BLUE_M004_BLOB
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- 1M for tables , name BLUE_M001_NTAB
- 256M for tables, name BLUE_M256_NTAB
Definition of each tablespace is like:
CREATE TABLESPACE BLUE_AUTO_INDX DATAFILE 'BLUE_AUTO_INDX01.DBF' SIZE 200M REUSE AUTOEXTEND ON NEXT 100M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 64M SEGMENT SPACE MANAGEMENT AUTO;
CREATE TABLESPACE BLUE_K064_BLOB DATAFILE 'BLUE_K064_BLOB01.DBF' SIZE 20M REUSE AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 64K SEGMENT SPACE MANAGEMENT AUTO;
CREATE TABLESPACE BLUE_K064_NTAB DATAFILE 'BLUE_K064_NTAB01.DBF' SIZE 20M REUSE AUTOEXTEND ON NEXT 20M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 64K SEGMENT SPACE MANAGEMENT AUTO;
CREATE TABLESPACE BLUE_K128_NTAB DATAFILE 'BLUE_K128_NTAB01.DBF' SIZE 20M REUSE AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 128K SEGMENT SPACE MANAGEMENT AUTO;
CREATE TABLESPACE BLUE_K512_CLOB DATAFILE 'BLUE_K512_CLOB01.DBF' SIZE 20M REUSE AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 512K SEGMENT SPACE MANAGEMENT AUTO;
CREATE TABLESPACE BLUE_M004_BLOB DATAFILE 'BLUE_M004_BLOB01.DBF' SIZE 20M REUSE AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 4M SEGMENT SPACE MANAGEMENT AUTO;
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CREATE TABLESPACE BLUE_M001_NTAB DATAFILE 'BLUE_M001_NTAB01.DBF' SIZE 100M REUSE AUTOEXTEND ON NEXT 50M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 1M SEGMENT SPACE MANAGEMENT AUTO;
CREATE TABLESPACE BLUE_M256_NTAB DATAFILE 'BLUE_M256_NTAB01.DBF' SIZE 512M REUSE AUTOEXTEND ON NEXT 256M MAXSIZE UNLIMITED LOGGING ONLINE PERMANENT EXTENT MANAGEMENT LOCAL UNIFORM SIZE 256M SEGMENT SPACE MANAGEMENT AUTO;
Does this structure of tablespaces ok? I mean if the logic of one tablespace for different EXTENT SIZEs looks ok?

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so this is exactly what happened...
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Snapshot too old in a very big undo tablespace

Hi,
I can see the snapshot too old error message in my alert log file.
ORA-01555 caused by SQL statement below (Query Duration=5 sec, SCN: 0x000d.a1e610e5):
It shows that query failed just after its start within 5 seconds. I really dont understand this in the presence of following facts
Current size of my undo tablespace is around 15G and undo retention is 180 minutes and for my environment, oracle recommends to use around 8 G size for undo tablespace if i want to use undo retention to be set for 180 minutes.
I am using oracle 9.2.0.6 and automatic undo management.
Thanks
Salman

Could it be that the ora-1555 is thrown by the statement in the alert log, but is really caused by another statement that has been sitting around since yesterday? Oracle may be trying to make read-consistent some data that the other statement used to have in undo.
I see this all the time if I don't kill off leftover sessions in the middle of the night. Darn users.
Search asktom.oracle.com for the error, many good explanations there and in his books. There are some application coding conditions that can cause this, too.
Also, try doing a full scan of the table - select some arbitrary column without a where statement. This may correct a "delayed block cleanout" condition. Google that for more info if you don't know about it.

How to switch undo tablespace

Dear all,
I have created a new undo tablespace named undotbs2, How can i switch all the session use the undotbs2?
Many sessions are running and using the old undo tablespace named undotbs1.

user7244870 wrote:
CKPT wrote:
Sb has already mentioned links how to manage undo..
For more reference check this below links.
http://oracleflash.com/32/Change-or-switch-undo-tablespace-in-Oracle-database.html
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/undo.htm#BABGJBJH
I can't open the link.
http://oracleflash.com/32/Change-or-switch-undo-tablespace-in-Oracle-database.html
Is there a specific reason that you are not willing to read the official doc link?
http://download.oracle.com/docs/cd/E11882_01/server.112/e16508/logical.htm#CNCPT1079
Aman....

Droping an undo tablespace ????????????????

Hi Gurus,
How to drop an undo tablespace in oracle 10.2.
when i issue drop tablespace undo including contents
it shows like "ORA-30013: undo tablespace 'UNDO' is currently in use"
Pls help it out......
Regards
Rajesh

The reason why you cannot drop this tablespace is because it has been declared as the undo tablesapace for the database by means of the UNDO_TABLESPACE instance parameter.
You have to create a new undo tablespace and change the undo_tablespace instance parameter value to point to the new undo tablespace:
ALTER SYSTEM SET UNDO_TABLESPACE=<N EW UNDO TS>;
Afterwards you will have to wait for a while before you are able to drop the current tablespace if there are active transactions or if the information is still required to perform flashback queries (it depends on the UNDO_RETENTION instance parameter), so it is suggested to temporarily reduce this value so you can perform the switch to the new tablespace and you can get rid of the current tablespace.
~ Madrid
http://hrivera99.blogspot.com/

Undo tablespace full even with no active transaction and undo_retention 10s

The 9.2.0.4 instance is AUM (auto undo management). The undo table space is 50G and is almost full.
I have set the undo_retention to 10, previously it was 10800 (3hours). I restart the database. Wait quite long time.
And search on the dba_undo_extents.
select sum(bytes/(1024*1024*1024)),status from dba_undo_extents d where d.tablespace_name='UNDOTBS2' group by status;
SUM(BYTES/(1024*1024*1024)) STATUS
.574447632 EXPIRED
45.5358887 UNEXPIRED
It is hard to explain. 10 seconds already passed, at least all the extents should be expired.
Why so many 45G is still unexpried.
Is there a bug for undo tablespace? how to fix it.
It is a rac instance, I am trouble shooting the undo tablespace issues.
The UNDOTBS2 is for node2 to use.

If you start the database in exclusive (one instance) mode then the database instance can have only one undo tablespace so I would not expect Oracle to do anything with the undo tablespace for the non-running instance.
Run you database as normal and generate undo. See if the status changes. If if does that would imply that Oracle does not expire undo unless the undo segments (rbs segments) are accessed. Please post back with results of what you see.
Between having batch production running on all my databases that use undo tablespaces and the fact we use uniform extent undo tabllespaces I am not in a position to try to duplicate what you are seeing.
HTH -- Mark D Powell --

Undo Tablespace and Temporary Tablespace - autoextend ?

- In general, should I allow the Undo Tablespace to grow (autoextend)?
- In general, should I allow the Temporary Tablespace to grow (autoextend)?

The size of undo tablespace should always keeps in mind otherwiase you eill get ORA-1555 or out of space errors.
This paper is to help DBA’s in calculating the size of UNDO tablespace by using a simple formula.
It is tough to know about the number of transactions and subsequently number of rows changed per second.
So I suggest having a “big undo tablespace” to start with and based on load, after doing some calculations and resize your UNDO tablespace.
In my case one of the applications was going to production (live), and I had no idea that how many transactions will happen against this database. All what I was told that there will be optimum (transactional) activity on this database.
So I started with UNDO tablespace with size of 3GB and datafiles with autoextend “on” .
Note:
In production, you must be very careful in using this (autoextend on) as the space may grow to inifinity very fast. So my advice is either dont use this option, or use with "maxsize" or continuously monitor space (which is tough).
I month later, I noticed the activity from V$undostat.
Here is the step by step approach:
Step 1: Longest running query.
SQL> select max(maxquerylen) from v$undostat;
MAX(MAXQUERYLEN)
1793
This gives you ideal value for UNDO_RETENTION. To be on the safer size you should add few more seconds to get the right value. So in my case, the size of undo retention should be say 2000 secs.
Step 2: Size of UNDO tablespace.
Size of UNDO needed = UNDO_RETENTION x [UNDO block Generation per sec x DB_BLOCK_SIZE] + Overhead(30xDB_BLOCK_SIZE)
Out of these we know UNDO_RETENTION and DB_BLOCK_SIZE
All we need is to find out “UNDO Blocks per second”
Which can be easily fetched from v$undostat
SQL> SELECT (SUM(undoblks))/ SUM ((end_time - begin_time) * 24*60*60) "UPS"
2 FROM v$undostat;
UPS
8.11985583
V$undostat stores data for every 10 mins and begin/end times are start/end time of those intervals. We multiplied it with 24*60*60 because the difference between two dates will be in days and to get to seconds, we need it to multiply with 24hrs*60mins*60secs
So now we have all the values needed.
Undo size needed = [8.12 x 2000 x 8192] + [30 x 8192] = 133283840 bytes = 127.11 MB

Cannot drop undo tablespace with Active extents but no active sessions

Hi all,
I am running on 10gr2 oracle database in a Linux 32 bit environment.
I have a corrupted undo datafile. I've been able to recover the datafile but still the alert logs is still showing that it is corrupted.
Now what I'm trying to do is to drop the old undo tablespace like the one discussed here Change undo tablespace in Oracle - Switch Oracle's Undo tablespace.
My problem is I have an Active extent but no active session corresponding to it:
SYS@ccasdb AS SYSDBA > SELECT a.name,b.status
FROM   v$rollname a,v$rollstat b
WHERE a.usn = b.usn
AND    a.name IN (
                  SELECT segment_name
                  FROM dba_segments
                  WHERE tablespace_name = 'UNDOTBS1'
                 ); 2    3    4    5    6    7    8
NAME                           STATUS
_SYSSMU18$                     PENDING OFFLINE
SYS@ccasdb AS SYSDBA > SELECT a.name,b.status , d.username , d.sid , d.serial#
2 FROM   v$rollname a,v$rollstat b, v$transaction c , v$session d
3 WHERE a.usn = b.usn
4 AND    a.usn = c.xidusn
5 AND    c.ses_addr = d.saddr
6 AND    a.name IN (
7               SELECT segment_name
8               FROM dba_segments
9               WHERE tablespace_name = 'UNDOTBS1'
10              );
no rows selected
but still cannot drop the undotablespace.
SYS@ccasdb AS SYSDBA > drop tablespace UNDOTBS1 including contents and datafiles;
drop tablespace UNDOTBS1 including contents and datafiles
ERROR at line 1:
ORA-30013: undo tablespace 'UNDOTBS1' is currently in use
Regards,
Tim

Yes i was able to recover the datafile but the alert_log kept on prompting that it is still corrupted. The datafile's status is online.
I want to kill the session/s contributing to the PENDING OFFLINE status of the rollback segment so I can already drop the undotablespace and so
that the alert log will stop prompting for that corrupted datafile in that UNDOTABLESPACE.
Can i Just alter the tablespace's datafiles to offline drop then just drop it. Then I drop the tablespace?

FLASHBACK OFF FOR UNDO TABLESPACE????

Hi all
As my Undo tablespace growing evryday 2 GB & NOW it reached 19,
Database size is 6GB only
using Oracle 10g Release 2 without patch Set (release 1002000100) on Hp-Unix OS
Can i use the Undo tablespace with FLASHBACK OFF option?
what are the Consequences for Turning off the FLASHBACK,
Can we use this type of Undo tablespace with Flashback OFF???
CREATE UNDO TABLESPACE UNDOTBS03 DATAFILE
'/app/oracle/product/oradata/prod/undotbs03.dbf' SIZE 1000M AUTOEXTEND OFF
ONLINE
RETENTION NOGUARANTEE
BLOCKSIZE 8K
FLASHBACK OFF;
THANKS ALOT

Oracle Flashback Database: feature is similar to conventional point-in-time recovery in its results, allowing you to return a database to its state at a time in the recent past. It is, however, much faster than point-in-time recovery, because it does not require restoration of datafiles from a backup and it requires application of fewer changes from the archived redo logs.
UNDO Tablespace: Oracle db save the old value when a process change data in undo tablespace.
I think that you can change de default UNDO tablespace as NO AUTOEXTEND, and
Configure
SET UNDO_MANAGEMENT=AUTO
SET UNDO_RETENTION= ( second need for logger transaction )
UNDO_RETENTION specifies (in seconds) the low threshold value of undo retention. For AUTOEXTEND undo tablespaces, the system retains undo for at least the time specified in this parameter, and automatically tunes the undo retention period to satisfy the undo requirements of the queries.
For fixed- size undo tablespaces, the system automatically tunes for the maximum possible undo retention period, based on undo tablespace size and usage history, and ignores UNDO_RETENTION unless retention guarantee is enabled.

UNDO tablespace initial dimension

Hi, I have installed Oracle XE Beta 2 on a Windows XP Professional pc: the percentage of the UNDO tablespace is 94,64%, and I have done no relevant operation on the db, is this ok?
Thanks,
Gianluca

Sorry. I mis-read the question. You're looking in HTML DB and your undo is at 94.64%?
When you say "no relevant operation", do you mean since creation? It sounds like you've done something. The 94.64% could still be completely normal but shouldn't be on a fresh install
Post the stats from that htmldb screen, i.e. user, undo and system tablespace sizes (used and free).
Thanks,
LewisC
http://blogs.ittoolbox.com/oracle/guide/

Undo tablespace growing fast

Hello All
We are having issues with undo tablespace growing... the oracle version is 10.2.0.1.0
the table is holding around 400000000 records and this table is also partitioned by range
any reason for this undo tablespace growing by at an high rate
regards
Kedar

Undo tablespaces are special tablespaces used solely for storing undo information. You cannot create any other segment types (for example, tables or indexes) in undo tablespaces. Each database contains zero or more undo tablespaces. In automatic undo management mode, each Oracle instance is assigned one (and only one) undo tablespace. Undo data is managed within an undo tablespace using undo segments that are automatically created and maintained by Oracle.
Every Oracle Database must have a method of maintaining information that is used to roll back, or undo, changes to the database. Such information consists of records of the actions of transactions, primarily before they are committed. These records are collectively referred to as undo.
Undo records are used to:
Roll back transactions when a ROLLBACK statement is issued
Recover the database
Provide read consistency
Analyze data as of an earlier point in time by using Oracle Flashback Query
Recover from logical corruptions using Oracle Flashback features
When a ROLLBACK statement is issued, undo records are used to undo changes that were made to the database by the uncommitted transaction. During database recovery, undo records are used to undo any uncommitted changes applied from the redo log to the datafiles. Undo records provide read consistency by maintaining the before image of the data for users who are accessing the data at the same time that another user is changing it.
You confuse TEMP with UNDO tablespace.
Best Regards,
Francisco Munoz Alvarez
www.oraclenz.com

Move an undo tablespace datafile while online

Having a spirited debate at work today. Is it possible, or has anyone successfully moved an undo tablespace datafile while keeping the database online? (Hypothetically someone created it in the wrong directory)
My logic:
Create a new undo tablespace B
Switch undo tablespace from A to B
Take tablespace A offline
Once A goes from 'PENDING OFFLINE' to 'OFFLINE' copy the file to new location
Alter database rename file location
Switch undo tablespace from B to A
Drop tablespace B
Any comments?

Yes I do understood that, but you don't have to "move" the datafile.
The procedure I proposed is just to create a new undo tablespace, drop the former and forget about it.
You can't "move" the file stricto sensu while the database is online, but nothing prevents you from switching from one tablespace to another. Once it's done, everything's fine. And if you're on 10G (r2?) you might even rename tablespace "B" to tablespace "A"!
Yoann.

Fragmentation in tablespace in oracle 9i

Hi All,
We have oracle 9.2.0.8 installed in solaris 9, database size is 1.5 TB, we are looking for the tablespaces which are suffering from the fragmentation.
We have locally manged tablesapaces in the database. so can you please tell me, is there any tablespace fragmentation in the locally managed tablespace in oracle 9i, and if it is there than how to relove the situation.?
thanks in advance

If you mean by fragmentation, a number of free space areas in the data files - sometimes called honeycombing, this script will show them to you.
SELECT 'free space'      owner,
        ' '               object,
        ' '               obj_type,
        f.file_name,
        s.file_id,
        s.block_id,
        s.blocks,
        s.bytes/1048576   mbytes
FROM dba_free_space s,
        dba_data_files f
WHERE s.file_id = &file_id
   AND s.file_id = f.file_id
UNION
SELECT owner,
        segment_name,
        DECODE(segment_type, 'TABLE',          'T',
                             'INDEX',          'I',
                             'ROLLBACK',       'RB',
                             'CACHE',          'CH',
                             'CLUSTER',        'CL',
                             'LOBINDEX',       'LI',
                             'LOBSEGMENT',     'LS',
                             'TEMPORARY',      'TY',
                             'NESTED TABLE',   'NT',
                             'TYPE2 UNDO',     'U2',
                             'TABLE PARTITION','TP',
                             'INDEX PARTITION','IP', '?'),
        f.file_name,
        s.file_id,
        s.block_id,
        s.blocks,
        s.bytes/1048576
FROM dba_extents s,
        dba_data_files f
WHERE s.file_id = &file_id
   AND s.file_id = f.file_id
ORDER
    BY file_id,
        block_id
However, when you look at the report you will see that in a locally managed tablespace, all of the free space 'chunks' are all 8 blocks, or a multiple of 8 blocks. This means that all of these free space chunks are able to be (re)used. And, they will be used. There is no need to do anything unless there is a pressing need to give disk back to the OS.

Is there so call "dedicated" UNDO tablespace in Oracle 9i and higher?

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