Some confusion on undo tablespace

Similar Questions

• Undo tablespace in oracle 10g

  Hi all;

  Hello!

  I'm confused about undo tablespace size.

  Under query showing my undo tablespace size is 120Mo.

  but DBA_TABLESPACE_USAGE_METRICS view showing the undo tablespace size is 4194302

  > > Check free space

  SQ > select t.tablespace, t.totalspace as ' TOTAL_SPACE (MB).

  round ((t.totalspace-fs.freespace), 2) as "USED_SPACE (MB)",
  FS. FreeSpace as "FREE_SPACE (MB).
  round (((t.totalspace-fs.freespace) /t.totalspace) * 100, 2) like "% used (s),"
  round ((fs.freespace/t.totalspace) * 100, 2) as "% free" of
  (select round (sum (d.bytes) /(1024 * 1024)) as totalspace,)
  tablespace dba_data_files d.tablespace_name d
  Group d.tablespace_name) t,.
  (select round (sum (f.bytes) /(1024 * 1024)) as freespace,)
  tablespace dba_free_space f.tablespace_name f
  Group of f.tablespace_name)
  FS where t.tablespace = fs.tablespace order of t.tablespace.

  
  

  TABLESPACE TOTAL_SPACE (MB) USED_SPACE (MB) FREE_SPACE (MB) % used free %

  ------------------------------ --------------- -------------- -------------- ---------- ----------

  EXAMPLE                                    100             68             32         68         32

  240 230 10 SYSAUX 95,83 4.17

  480 475 5 98.96 SYSTEM 1.04

  UNDOTBS1                                   120            120              0        100          0

  1005 75 930 USERS 7.46 92.54

  SQL > select * from dba_tablespace_usage_metrics, where nom_tablespace like '% UNDO;

  NOM_TABLESPACE USED_SPACE TABLESPACE_SIZE USED_PERCENT

  ----------------------------    ----------  ---------------  ------------

  UNDOTBS1                              440        4194302 .010490422

  This is because:

  Tablespace_size in DBA_TABLESPACE_USAGE_METRICS takes the maximum file size for CanGrow tablespace that matches maxblocks in dba_data_files.

  This is not the same value you can get from dba_data_files.

  DBA_TABLESPACE_USAGE_METRICS shows essentially the maximum size to which a data file can grow. And DBA_DATA_FILES (+ DBA_FREE_SPACE) the current size of the tablespace.

  Watch more document MOS (My Oracle Support):

  Difference in size of dba_data_files Tablespace and dba_tablespace_usage_metrics/V values $ Filespace_usage (Doc ID 455715.1)

• Full undo tablespace confusion

  Hi gurus,
  
  We have a 2 RAC on RHEL 6.2 node (11 GR 2). We have 2 undo tablespace UNDOTBS1 and UNDOTBS2. Who controls the stats of DBA_UNDO_EXTENTS it gives different results. Please help me understand the difference below the query results. Also, if possible any ORA-01555 or ORA-30036?
  
  
  
  On node 1.
  
  SQL > SELECT STATUS DISTINCT, SUM (BYTES) / 1024/1024, COUNT (*) FROM DBA_UNDO_EXTENTS where nom_tablespace = 'UNDOTBS1' group by status
  2;
  
  STATUS SUM (BYTES) / 1024/1024 COUNT (*)
  --------- -------------------- ----------
  RUN 57352.1875 6087
  64.25 5 EXPIRED
  ACTIVE 841 35
  
  1 * SELECT STATUS DISTINCT, SUM (BYTES) / 1024/1024, COUNT (*) FROM DBA_UNDO_EXTENTS where nom_tablespace = 'UNDOTBS2' group by status
  SQL > /.
  
  STATUS SUM (BYTES) / 1024/1024 COUNT (*)
  --------- -------------------- ----------
  9090,8125 1240 REST TO RUN
  ACTIVE 1374 46
  47323,75-7125 EXPIRED
  
  
  SQL > SELECT STATUS DISTINCT, SUM (BYTES) / 1024/1024, COUNT (*) OF DBA_UNDO_EXTENTS group of status;
  
  STATUS SUM (BYTES) / 1024/1024 COUNT (*)
  --------- -------------------- ----------
  REST TO RUN 66185 7322
  EXPIRED 47380 7129
  ACTIVE 2600 94
  
  
  
  On node 2.
  
  SQL > SELECT STATUS DISTINCT, SUM (BYTES) / 1024/1024, COUNT (*) FROM DBA_UNDO_EXTENTS where nom_tablespace = 'UNDOTBS1' group by status
  2;
  
  STATUS SUM (BYTES) / 1024/1024 COUNT (*)
  --------- -------------------- ----------
  57281.4375 6090 REST TO RUN
  1096 45 ASSETS
  
  SQL > SELECT STATUS DISTINCT, SUM (BYTES) / 1024/1024, COUNT (*) FROM DBA_UNDO_EXTENTS where nom_tablespace = 'UNDOTBS2' group by status
  2.
  
  STATUS SUM (BYTES) / 1024/1024 COUNT (*)
  --------- -------------------- ----------
  RUN 56404.5625 8362
  ACTIVE 1320 48
  72 2 EXPIRED
  
  SQL > SELECT STATUS DISTINCT, SUM (BYTES) / 1024/1024, COUNT (*) OF DBA_UNDO_EXTENTS group of status;
  
  STATUS SUM (BYTES) / 1024/1024 COUNT (*)
  --------- -------------------- ----------
  REST TO RUN 113575 14454
  ACTIVE 2543 93
  EXPIRED 64 1
  
  
  Why is there so much difference in the outcome. Help, please
  
  Kind regards
  Nikhil Mehta.

  Hello
  It's a bug because dependent parameters for undo retention are really time-sensitive and specific to the instance.
  It is difficult to find a perfect "global" solution. Therefore, there is no solution for this.

  Then use the bellow note to determine the correct result.

  * DBA_UNDO_EXTENTS shows incorrect results of different nodes of the PAP [1492313.1 ID] *.

  Kind regards
  Levi Pereira

• Undo Tablespace queries

  Hi all
  
  I am little confused with reading on the undo tablespace. So I need some clarification
  
  1. There are 2 undo tablespace in our application. Could someone explain to me how the 2 undo tablespace? I've not found details about it.
  2. both the undo tablespace is used at 100%. Where the the new transaction will go? New operation will force the blocks used to be exceeded if necessary?
  3. what should be the ideal size of the tablespace undo compared to the total storage size?
  4. is the log archive associated with space undotable? If Yes, then when archiving logs getting generated?
  
  Thank you

  1. in a database of CARS, each Instance must have it's own Undo Tablespace.
  In a database not RAC (single instance), only one Undo Tablespace can be active at any time. The Undo Tablespace would be idle but can be switched by an ALTER SYSTEM SET UNDO_TABLESPACE command.

  2. even if an Undo Tablespace is 'used 100% ' Oracle can expire (and even drop) on old extents and segments that are no longer needed by the value of Undo_Retention. Thus, data undo for older transactions that are committed (more than Undo_Retention period has elapsed since the validation) will be overwritten.

  3. There is no "ideal size. Undo sizing is based on transaction volumes, fluctuations in the volume of transactions, query patterns etc.

  4. No, there is no direct relationship between the two. However, any cancellation that is generated is also written again - that is to say redo Undo catches as it captures changes made to Tables, indexes etc..

  I suggest you read the Oracle documentation concepts to
  http://download.Oracle.com/docs/CD/E11882_01/server.112/e16508/TOC.htm

  Hemant K Collette
  http://hemantoracledba.blogspot.com

• It will frequently commit resolve ora-30036 (cannot extend the undo tablespace)

  I use 11.2.0.3 database. I confused on the use of validation to resolve ora-30036.

  I have the script in migration once that has many updates and I'm getting ORA-30036 (unable to extend segment by 4 in the "UNDOTBS" undo tablespace) .

  Our undo tablespace in NO mode autoextend and like this is just a one time event, we will not increase it.   He is currently 6 GB.

  We would commit determination ORA-30036 in my case? If not why? Is there a better solution to solve it.

  
  

  When I say commit frequent, I won't commit after each line, I just want to commit after may be million lines, so that my active cancellation extend turn into cancellation remaining will extend and Oracle will be able to use it in case of pressure of space.

  
  

  Note:

  UNDO_MANAGEMENT: AUTO

  UNDO_RETENTION: 2700

  Undo tablespace retention is NOGAURANTEE.

  I have the script in migration once that has many updates and I'm getting ORA-30036 (unable to extend segment by 4 in the "UNDOTBS" undo tablespace).

  Our undo tablespace in NO mode autoextend and like this is just a one time event, we will not increase it.   He is currently 6 GB.

  Why don't you increase it?

  You must use the correct size of UNDO necessary for the work that will be done.

  A lot of shops to create a for big lots new UNDO tablespace and then switch to it for batch processing. Once the task is completed, they switch back to the normal UNDO. That prevents the normal RETURN of autoextending far where it is normally necessary:

  ALTER SYSTEM SET UNDO_TABLESPACE

• Changing data in the undo tablespace or db Oracle buffer cache

  Hello
  
  I have serious doubt in the feature of oracle architecture, when a user issues an update statement, the data blocks are transported to the db buffer cache and where the data changes are made? Made a copy data block is stored in the cache db pads and the changes are made to the block in the buffer cache? or the copy of the data block is stored in the undo tablespace and changes are made to the blocks in the undo tablespace?
  
  In singles, the changes to the data blocks are make to the db or undo tablespace buffer cache?
  
  
  Thanks in advance
  
  Kind regards
  007

  Did you have a look to the Internet for the answer?

  In short, if a trial Oracle wants to update a record in the table, it does:

  -Read the record to be changed in the buffercache
  -Audits (the record already locked, is the update allowed)
  -Put the folder (called image before) in a rollback in the UNDO tablespace segment
  -Writing redo information about this change in the UNDO tablespace
  -Lock the record
  -Write the change in registration in the buffer cache
  -Put the change also in the redo buffer
  S ' sit and wait... (for a commit or a rollback)

  When are committed:
  -Release the lock
  -Empty folder of restoration since the UNDO tablespace
  -Write a record of this change forward in the UNDO tablespace

  When rollback:
  -Release the lock
  -Rinse the record changed the buffercache
  -Read the original value
  -Empty folder of restoration since the UNDO tablespace
  -Write a record of this change forward in the UNDO tablespace

  It of here, some more specific complexity when a checkpoint occurs between the change and the commit / rollback or redo buffer has been emptied for redo files

  Please any other s/n, correct me if I'm wrong...

  See you soon
  FJFranken

• UNDO tablespace fills

  My undo tablespace fills due to no deletions by the jdbc thin client sessions.
  How can I solve this problem permanently?
  
  The undo tablespace size is 5.5 GB
  
  I am facing a complete problem of the undo tablespace
  Here are the sessions that may be causing the problem.
  
  
  Select s.sid,
  s.Serial #.
  s.sql_id,
  s.prev_sql_id,
  s.SCHEMANAME,
  s.OSUSER,
  s.Program,
  USED_UBLK, USED_UREC from v$ session s, v$ transaction t where order of s.taddr = USED_UREC t.addr;
  
  3909 30842 fgcp0qn1bqzx9 XLTDB5 xltwrk5 JDBC Thin Client 504 45257
  5133 53593 fgcp0qn1bqzx9 XLTDB5 xltwrk5 JDBC Thin Client 07 54482
  4525 35108 fgcp0qn1bqzx9 XLTDB10 xltwrk10 JDBC Thin Client 2381 192853
  4428 38484 fgcp0qn1bqzx9 XLTDB1 xltwrk1 JDBC Thin Client 8682 634540
  
  
  For this sql id: fgcp0qn1bqzx9 there are more than 14 executions k / hour.
  
  This is the query for this sql id:
  / * TJAPI_SubTrxTransient_deleteTrb1SubTrxTransient_0 * / REMOVE FROM TRB1_SUB_TRX_TRANSIENT
  
  Some other details
  ++++++++++++
  Oravle version: 11.1.0.7
  OS: SunOS
  ++++++++++++

  Details of the message from the database pl and OS versions. From 10 g 2, cancellation will still appear to be 'full' - which is normal.

  Doc 413732.1 - Full UNDO Tablespace in 10gr 2 MOS

  HTH
  Srini

• Undo tablespace is used

  Hello
  
  I have a database that was created in the CARS and was converted into standalone sometime some time. There are always 2 Undo tablespace on this database. In looking at dba_undo_extents, we have first active, expired and Unexpired extensions. But second one only expired scopes. I think that the second is not used since DB has been converted, but I'm not sure. How can I tell how old are extended in this tablespace?
  
  Auxiliary question: I also on this newspaper of DB recovery for 2 threaded that no longer exists... How can I get rid of them?
  
  Kind regards
  
  Fred

  Select * from dba_rollback_segs where nom_tablespace =

• UNDO Tablespace backup-RMAN

  Hi/team champions,
  I'm confused in full DB Backup RMAN why CANCEL tablespce is included even we include also archive logs.
  in a Word?
  Why UNDO tablespace backup is necessary while taking backup RMAN?
  
  Kind regards
  Shitesh Shukla

  If I do not want to include the UNDO tablespce in my backup

  What happens if I took only backup files except CANCELLATION n TEMP

  NOT an option. You must include UNDO. 11g has optimization in order to safeguard an Undo tablespace.
  10 gr 2 what you pourriez do is

  1. create a new Undo Tablespace
  2. position yourself in the new Undo Tablespace
  3. check that the old Tablespace Undo is no longer in service - confirm that there is no transaction active in the inside undo segments
  4. remove the old Undo tablespace
  5. start your RMAN backup

  You run the risk of
  a. wait long to step 3
  b. ORA - 1555 s for users once you drop the Undo tablespace to step 4.

  Hemant K Collette
  http://hemantoracledba.blogspot.com

• Transaction is written to the log file and it is not written to undo tablespace. During a failure of the system how oracle rolls back the transaction.

  Hi all

  My question is:

  Transaction is written to the log file and it is not written to undo tablespace.

  During a failure of the system how oracle rolls back the transaction.

  I have already provided the answer, you ignored if well (you seem to only read the responses by people of your country).

  Redo log is always written * first * before * writing to the data block (redo log writing is much more aggressive). So it DOESN 'T MATTER if you lose these scriptures of rollback segment.

  Valuation: rear roller followed by roll forward, using redo log files and/or archive redo log files.

  Sybrand Bakker

  Senior Oracle DBA

• How to UNDO tablespace size?

  As legend. Thank you!

  An UNDO tablespace sizing requires three data items.

  (UR) UNDO_RETENTION in seconds
  (UPS) Number of undo the blocks of data generated per second
  (DBS) Overhead varies on position and size of the file (db_block_size)

  The necessary cancellation space is calculated as:

  UndoSpace = HEART * (UPS * DBS)

  read the Doc ID 262066.1 it has retail formula.

• undo_segments in the undo tablespace

  (1) at least how undo_segments in undo tablespace?

  Is optimal?
  If I increase the size of the undo tablespace, undo_segments counts also have increased!

  Version of DB is 10g

  Hello

   

  The two time oracle maintains exactly 10 segments. (you can see nom_segment begins by _SYSSMU11)

  I'm not clear on what exactly 10 segments. I have undo tablespace of ~ 250 GB with 6676 stored in dba_rollback_segs.

  3) why undo tablespace with the only spaceMo 46,8125 '?

  
  

  (4) I mean why he is stiil 450Mo undo_retention even through time or same validation has occurred?

  Just Oracle - Doc

  Once a transaction is committed, the undo data are more necessary for purposes of recovery rollback or transaction. However, for consistent read purposes, long-running queries may require old undo information to produce older images of data blocks. In addition, the success of several Oracle Flashback features can also depend on the availability of the old cancellation information. For these reasons, it is desirable to keep the old information of cancellation for as long as possible.

  Introduction to the management of the automatic cancellation

  With undo tablespace, you would see extended with the status ACTIVE, EXPIRED, extents still to RUN.

  Active cancellation extended are used by transactions and will be always active, because they are needed for the restoration.

  Extensions has expired are not used by transactions, the data contained in these extended is committed and the time UNDO_RETENTION is passed, so it is not necessary for the coherence of reading and can be reused.

  Not expired extensions are extended no assets but honor UNDO_RETENTION. Transactions belonging to these bodies of cancellation are determined, but the retention time has failed, and it may be necessary for the coherence of reading!

  Paste the query result - below

  ! undo_extent_stat.SQL more

  status of collar for a30

  Select the State,

  round (sum_bytes / (1024 * 1024), 0) like MB,.

  Tour ((sum_bytes / undo_size) * 100, 0) as PERC

  Of

  (

  Select the State, sum (bytes) sum_bytes

  of dba_undo_extents

  Status group

  ),

  (

  Select sum (a.bytes) undo_size

  from dba_tablespaces c

  Join v$ tablespace b on b.name = c.tablespace_name

  Join v$ datafile on a.ts # b.ts = #.

  where c.contents = 'UNDO '.

  and c.status = 'ONLINE '.

  );

  Anand

• Concept on Undo tablespace in RAC environment

  Why we need two different Undo tablespace for two different instances in RAC environment. What are the internal mechanisms behind it? No explanation of the concept will be great for me. What will be the scenario if we have same tablespace undo for two instances?

  Thanks in advance.

  Hello

  To reduce CONTENTION and the complexity of the software.aslo oracle instances share not undo tablespace using cancel separate increase the availability of data undo files.

  Note: all instances can still read that cancel all blocks for coherent reading purposes. In addition, any instance can update the any tablespace undo during the restoration of the transaction,

  as long as undo tablespace is not currently used by another instance to cancel generation or a recovery operation.

  HTH

  Tobi

• Need information on objects not expired undo tablespace

  We are facing a problem in our database for 3-4 days.

  The objects remaining in the database increases day after day. As our ts cancel autoextend enabled, it increases the storage space.

  Currently the following is the scenario.

  SQL > SELECT DISTINCT STATUS, SUM (BYTES) / 1024/1024/1024 GB, COUNT (*)

  2 GROUP OF DBA_UNDO_EXTENTS BY THE STATE;

  STATUS GO COUNT (*)

  --------- ---------- ----------

  61.5925903 10995 REST TO RUN

  3.33197021 356 EXPIRED

  ACTIVE 18.478515625

  Thus, the remaining data 61GB while active is only 478 MB and expired is 3.3 GB.

  My questions are

  1. How can I check the object or sql query or a program that contains the data to cancel "RUN" so. How can I find the names of these objects?

  2. If I turned off autoextend undo ts if this solves the problem and take the new space to cancel from space to cancel remaining?

  Help, please.

  1. the UNEXPIRED is not bound to a query, but the UNDO for UNDO Tablespace retention period. And the Undo retention is a value set automatically when the parameter UNDO_RETENTION is minium.

  The Oracle Documentation says:

  For an undo tablespace with the AUTOEXTEND option is enabled, the database tries to honor the specified minimum retention period by UNDO_RETENTION . When space is low, instead of crushing the cancellation information remaining, the self-aggrandizing tablespace' extends. If the MAXSIZE clause is specified for an auto-croissant undo tablespace when the maximum size is reached, the database can begin to replace the cancellation information remaining.

  2. Yes this will fix the issue that now the calcution for UNDO retention is different.

• MAX limit for segment undo undo tablespace

  Hello Experts;
  
  Where tick No, max of segments of cancellation in the Oracle database?
  

  Is limited and depends on the SIZE of the DB or UNDO tablespace size?

  Thanks in advance...

  969352 wrote:
  What?

  dba_data_files - I thought that from here we can not get undo_segments County!

  not serious... Thank you...

  You started this thread, ask questions about the size of UNDO limit; which is a direct function of DBA_DATA_FILES.

  Then you changed question about County segment UNDO. which is a direct function of DBA_SEGMENTS.

  so take your decisions about what question should be answered.