Question about Undo Tablespace?

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• Question about ALTER TABLESPACE add datafile on/slide

  Good afternoon
  
  As an exercise, I created a STORETABS tablespace and added a data file using the command:
  

  SQL> alter tablespace storetabs add datafile 'e:/storetabs3.dbf' size 50M;

  This successful step. A new file was created at the root of e: as expected.
  
  Following this command, I have published:
  

  SQL> alter tablespace storetabs drop datafile 'e:/storetabs3.dbf';
  
  Tablespace altered.

  The command succeeded. However, the file * ' e:/storetabs3.dbf' * has not been deleted. After re-reading the documentation found at http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/statements_3002.htm, I feel that deleting the operating system file itself is something that must still be done manually.
  
  Question: Am I right that there is no option to cause 'alter tablespace < tablespace > drop datafile < datafilename >' remove it the o/s file? In other words, should the o/s file always be deleted manually as a separate step?
  
  Thank you for your help,
  
  John.

  John,

  Don't know what part of the documentation page you are referring to but on the same page to the following location
  http://download.Oracle.com/docs/CD/B28359_01/server.111/b28286/statements_3002.htm#sthref5437,
  He clearly staes

  Specify DROP to drop from the tablespace an empty datafile or tempfile specified by filename or file_number.
  This clause causes the datafile or tempfile to be removed from the data dictionary and deleted from the operating system.
  The database must be open at the time this clause is specified
  

• Question about list tablespace temp of the oracle 12 c container

  Select con_id, name of the containers of v$.  -> 4 lines returned.

  1	CBD$ ROOT
  2	PDB$ SEEDS
  3	PDBRED
  4	PDBBLUE

  Select con_id, name from v$ tempfile;  -> 4 lines returned.

  1	/U01/app/Oracle/oradata/cdb1/temp01.dbf
  2	/U01/app/Oracle/oradata/cdb1/pdbseed/pdbseed_temp01.dbf
  3	/U01/app/Oracle/oradata/cdb1/pdbred/temp01.dbf
  4	/U01/app/Oracle/oradata/cdb1/pdbblue/pdbseed_temp01.dbf

  Select cdb_tablespaces TABLESPACE_NAME, CON_ID where nom_tablespace like '% TEMP;   -> 4 lines returned.

  4	TEMP
  3	TEMP
  2	TEMP
  1	TEMP

  Select * from v$ temp_space_header; <-why to return a row ?

  1

  TEMP

  12 c bug?

  Hello

  and here you have the answer. The dictionary table ts$ contains only the 'local' tablespaces (in your case, those of the CBD).

  FYI - the join condition of the view GV$ TEMP_SPACE_HEADER is based on the following clause:

  from ts$ ts, x$ktfthc hc where ts.contents$ = 1 and ts.bitmapped <> 0 and ts.online$ = 1 and ts.ts# = hc.ktfthctsn and hc.ktfthccval = 0
  

  The view V$ TABLESPACE is based on the control file, not the Oracle dictionary table (as mentioned in the official documentation here: http://docs.oracle.com/cd/E16655_01/server.121/e17615/refrn30277.htm#i1420852 - "V$ TABLESPACE contains an tablespace from the file of control."), but the control file (fixed table x$ kccts) lack the necessary block size information for the calculation. You can write your own query based on x$ kccts and x$ ktfthc, if you use a specific block size (in all environments and each time), but Oracle itself should be more generic, of course.

  Concerning

  Stefan

• 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)

• How to reduce the UNDO Tablespace

  Hello
  We had an UNDO Tablespace to 22 GB but it's using just 2GB. How to shrink the undo tablespace. We use the database in production cluster 3 node 10.2.0.4
  Is there is way we can worry about UNDO Tablespace or should I create an UNDO tablespace and assign the undo tablespace to DB and let fall the old CANCEL?
  How to ensure that the transactions are done and free to abandon the old CANCEL?
  That's what we must restart all three nodes each node has its own UNDO Tablespace.
  
  Need help on this issue.
  
  would appreciate your quick response.
  
  
  Thank you

  No you have not.

  concerning
  Mohamed

• Undo Tablespace - newbie question

  Q1. An Undo Tablespace is required in a database? I thought that only agents were SYSTEM and SYSAUX of TEMP?
  
  Q2. What happens if you do not have an Undo Tablespace?
  
  Q2. How are they an Undo Tablespace to undo / Rollback Segments in a database?

  Jim,

  I did not notice that it is not mentioned in the documentation, or at least I couldn't find if its somewhere. But when 9i has been released, I'm sure that stated explicitly that the number of segments that would be created is 10.

  However, what determines exactly how much is created in the first place? In my case, my database has 61 segments!

  But are you sure that 61 segments belong to a single undo tablespace? My best guess is that you have several Undo tablespace created and the number of segments is of each of them. Can you check and confirm please?

  I understand that the parameter UNDO_RETENTION will determin when these segments can be replaced, but I am trying to get my head round how my database has finished with 61 undo segments and will be he never ever get rid of the any of these segments? (i.e. is it just continue to add but never remove all know is that as a concept of the high water line?)

  Not to my knowledge at least. I know that the number of segments can be less than the number 10, but more which would be created at any time and that too in such a number of top, no, did not meet any reference that has never mentioned it.

  LSO a number of segments are offline - why should it be?

  Yet once, which just goes to confirm my doubt that these segments are displayed including tablespaces offline are not defined by default for your database. A tablespace can be set to the default db only its segments, and it would have also shown online. Again, check parameter undo_tablespace and see dba_rollback_segs as if the segments that are shown as online, belong only this tablespace or more.

  HTH
  Aman...

• 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.

• Question about REDO

  I have a question about roll FORWARD.
  
  We know that when changes to databases... online redo file change logs.
  
  In books and various documents, it is mentioned that redo logs also store 'image' of the data before. Before the Images go to UNDO Tablespace and contributing to restoring
  
  My question is why do the newspapers 'image' of the data before store? What is the main purpose of storage before the image of the data in the REDO logs?
  
  
  Please explain.
  
  Thanks in advance.

  Here is the nice discussion.

  Difference between newspapers redo and undo tablespace
  Difference between newspapers redo and undo tablespace

  HTH
  -André

• 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

• 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.

• 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 MANAGEMENT

  Hello
  I'm trying to remove 90 columns of a partitioned table big. I was trying a physical decline first and since it takes more time, I decided take unused columns and drop them. However, I could put in unused condition.
  Now I'm trying to drop these unused columns in the table, it has run for 22hours approx. I'm keep increasing the undo tablespace to store the undo data.
  I have also diminished the undo_retention at 300 to 900.
  
  My question is there a better way to drop these columns. And is it possible to flush out the undo data.
  
  Your valuable response is greatly apprecaited.
  
  Thank you

  Hello

  Have you checked the link, can it help to use the checkpoint to the drop statement

  http://asktom.Oracle.com/pls/asktom/f?p=100:11:0:P11_QUESTION_ID:623063677753

• Undo tablespace increasing

  Hello
  
  my version of the database is 11.2.0.1.0
  
  My undo tablespace was approximately 36 GB and 4 GB was about free.
  
  But now the size decreases and it is falling fast. What I would do. I increased it by another 2 GB. How to monitor it so that I can capture it without resizing again.
  Please guide me.
  
  Thanks in advance.

  to understand correctly read
  http://blog.oracle48.nl/Oracle-database-undo-space-explained/

• Undo tablespace full

  Hi all
  
  OS: Solaris
  DB: 10 G
  
  My undotablespace had a lot, I should directly resize it or is there something else I should do first?
  One last thing, if I take the bounce of the database, this will affect cancel it?
  
  Kind regards
  Sphinx

  If you have room for an other undo tablespace, why not make one you have more? Don't forget, one will not be removed until all transactions using this are made.

  There are a few reasons you may need more to cancel the space: you have people leaving the open sessions, you have poor code that uses too or shot himself in the foot, stand too close, autoextend to cancel gourmand or you really need the space.

  Tom Kyte has recommended to keep enough space around it for annual transactions of large batch if you have those. Unfortunately, this means that you do not have the other stuff stupid user. I take an intermediate point of view, keeping a great cancel (it is about half of my db), even though it is barely used most of the time and kill sessions where I can determine that they should not be left open (in other words, people who rarely run stuff from one day to the next day to ask, since most people don't).

  What are the exact errors are you seeing? If this is the code that self-destructs in the foot, no matter how cancel it y a. search for ora-1555 on asktom if that's what you see. What's your retention, what is your guarantee?

• Undo tablespace continues to grow

  Hello
  My undotbs grows to 14g (even if I have my undotbs actul size 9g) I try to resize the data files, but
  This may not work.
  
  So, I guess for this task
  
  >
  -Create a new as undo tablespace:
  SQL > create undo tablespace UNDOTBS2 datafile "< full file path >" size < small >;
  
  -Change the parameter UNDO_TABLESPACE
  SQL > alter system set UNDO_TABLESPACE = UNDOTBS2;
  
  -Remove UNDOTBS1
  SQL > drop tablespace UNDOTBS1 including content and data files; >
  
  but my question is, is he worthy of delete the undotbs1 whose having a lot of data and if I deleted
  These data (undotablespace), I won't be able to completely recover?
  
  db_version:10.2.0 (Linux)

  There is procedure to drop undo tablespace. If you already increase first then I suggest you to study why his is growing? Check with developers, to monitor the database