Redo and undo logs

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• relationship between redo log buffer, journal of redo and undo tablespace files

  What is the relationship between the redo log buffer, redo log files and undo tablespace?
  
  what I understand is
  
  redo log buffer is the logical area where all the news of recovery were stored until they are transferred by LGWR bank roll forward log online... but y at - it report any with the undo tablespace with these two?
  
  Please correct me if I'm wrong
  
  Thanks in advance

  redo log buffer is the logical area where all the news of recovery were stored until they are transferred by LGWR bank roll forward log online... but y at - it report any with cancellations

  tablespace with these two?

  There is a link between files redo log and buffer, but the undo tablespace is something else entirely.

  spend it here with this links

  REDO LOG FILES
  http://www.DBA-Oracle.com/concepts/redo_log_files.htm

  BUFFER REDOLOG
  http://www.DBA-Oracle.com/concepts/redo_log_buffer_concepts.htm

  UNDO TABLESPACE
  Undo tablespace to cancel files to undo or roll back uncommitted changes pray the database.

  Hope you understood.

• Instance - Redo and Undo recovery question

  I'm a little confused about how to undo and redo used to restore, please help me to clarify this point. If redo records changes (validations and database changes to cancel the revenge), don't do it again and undo all come from the log to roll forward to instance recovery? What is the source of the undo data, do it again save or cancel the segments that have been rebuilt using recovery logs?
  
  Matt

  In simple terms:
  Source of redo - redo logs, source of cancellation - undo tablespace. Oracle applies again to the data files, including cancellations of TBS, first, then it restores the unvalidated data using TBS of cancellation.

• Repeat and undo operations in the jargon.

  I wanted to know how you people develop redo and undo method in a project manager using lingo? Is there a standard feature that keeps track of interactions with the user and provides the traditional method of redo and undo? Or I should develop its own logic? I'm new to programming lingo, so ask people experienced you how on this subject?

  You must back up the positions of sprites in a list for this.

  Ex: my_sprite1_position_H =

  my_sprite1_position_V =

  Then, you set the loch and locV of your sprites when you need:

  example, if you go back to section 2:

  Sprite (1) .locH = my_sprite1_position_H [2]

  Sprite (1) .locV = my_sprite1_position_V [2]

  Brahim

• Difference between redo logfiles, Undo Tablespace, Archive log data file

  Can some please highlight the difference between Undo and Redo Logs
  Also why we need to separate the archive logs when the recovery log data can be written directly in data files...
  
  Help you will be highly appreciated...

  Hello

  Ed gave you a very good answer.

  Rememeber database files are online and they are written to by DBWR process. So we have the database files, redo log files and archive logs.
  In order to avoid all the crawl log when you perform a recovery, database performs control points that summarize the State of the database. This operation of control point provides a shortcut to the recovery. At the checkpoint, the database knows that all incorrect pages were written to disk (for example, database files). At the time of recovery, the log (which includes-finished and unfinished transactions) is used to bring the database to a consistent state. The system locates the time of the last checkpoint and returned to this position in the log file. Then he restores forward all completed transactions (read committed) that occurred after the last checkpoint and rolls back all transactions that were not committed, but that began before the last checkpoint. This is where online log files are used.

  Now imagine that you need to back up your database GB 100 + all 10 minutes. It would be a waste of space! So you take a backup of your database at time t and backups of archiver process redo logs periodically to check the newspapers so that redo log files can be replaced and RMAN will use the last backup and archive the log files to recover your database at the time.

  Now, I mentioned the checkpoint process. The Checkpoint process regularly launches a control point that uses DBWR to rewrite all the blocks Sales in the data files, so synchronize the database. Imagine one dam is running and have exhausted all the redo log files. At this point, Oracle will wait until all Sales already queued blocks have been written to the buffer on disk (database files) foremost him redo log files can be considered as superfluous and available for re-use (i.e. can be overwritten). This will result in the following message in the alert.log:

  Thread 1 advanced to log sequence 17973
    Current log# 3 seq# 17973 mem# 0: /oracle/data/HAM1/log3aHAM1.dbf
    Current log# 3 seq# 17973 mem# 1: /oracle/data/HAM1/log3bHAM1.dbf
  Thread 1 cannot allocate new log, sequence 17974
  Checkpoint not complete
    Current log# 3 seq# 17973 mem# 0: /oracle/data/HAM1/log3aHAM1.dbf
    Current log# 3 seq# 17973 mem# 1: /oracle/data/HAM1/log3bHAM1.dbf
  Thread 1 advanced to log sequence 17974
  

  I am sure you have done the following:

  alter database mount;
  
  Database altered.
  

  When you mount a database, Oracle combines the instance started the database. Oracle control files are opened and read. However, no checking such as the restore/recovery is performed

  alter database open;
  
  Database altered.
  

  An open command opens the data files, recovery logs, it performs automatic and consistency of database recovery. At this point, the database is now ready to be used by all valid users.

  HTH,

  Mich

  Published by: Mich Talebzadeh on November 19, 2011 16:57

• Redo Log and Supplemental Logging doubts related

  Hi friends,
  
  I am a student extra import logging in detail. Reading a lot of articles and the oracle documentation to this topic and redo logs. But couldnot find answers some doubts...
  Please help me to delete.
  
  Scenario: we have a table with primary key. And we execute a query update on the table that does not use the primary key column in a clause...
  Question: in this case, the roll forward records entry generated for changes made by put request to update contain primary column values... ?
  
  Question: If we have a table with primary key, we need to enable additional logging on primary column of this table? If so, in what circumstances, do we need to?
  
  Question: If we set up replication streams on this (having the primary key) table, why do we really need to enable saving of its complementary (I read documentation saying that flow requires some then more information., but in reality what information does it. Once again this question is closely related to the first question.)
  
  Please suggest also any good article/site that provide inside details of the redo log and additional logging, if you know.
  
  Kind regards
  Lifexisxnotxsoxbeautiful...

  (1) assuming that you do not update the primary key column and additional logging is not enabled, Oracle doesn't have to log in the primary key column in the log to roll forward, just the ROWID.

  (2) is rather difficult to answer without being tautological. You need to enable additional logging if and only if you have some use downstream for additional columns in the redo logs. Rivers and streams, these technologies built above are the most common reason to enable additional logging.

  (3) If you run an update as

  UPDATE some_table
    SET some_column = new_value
   WHERE primary_key = some_key_value
     AND <>
  

  and look at an update statement that LogMiner relies on newspapers in recovery in the absence of additional record, basically it would be something like

  UPDATE some_table
    SET some_column = new_value
   WHERE rowid = rowid_of_the_row_you_updated
  

  Oracle has no need to replay the exact SQL statement you issued, (and so he doesn't have to write the SQL statement in the redo log, he doesn't have to worry if the UPDATE takes a long time to run (otherwise, it would take so much time to apply an archived log as it did to generate the log) ((, which would be disastrous in a recovery situation) etc.). He just needs to rebuild the SQL statement of the information contained in the restoration by progression, which is just the ROWID and the columns that have changed.

  If you try to execute this statement on a different database (via the stream, for example) may the ROWID on totally different destination database (since a ROWID is just a physical address of a line on disc). So adding additional record tells Oracle to connect to the primary again key column and allows LogMiner / flow / etc. to rebuild the statement using the values of the primary key for the changed lines, which would be the same on the source database and destination.

  Justin

• difference between online redolog files and archived log files

  What is the fundamental difference between archived log files and online redo log files? .. .plz keep things simple as m a newbie

  Online redo log:

  Redo online Oracle log files are filled with records of restoration by progression. A record of remake, also called entrance to roll forward, is composed of a group of agents of change, each of which is a description of a change to a single block in the database. Each instance of an Oracle database has an associated online redo log to protect data in case of failure of the instance.

  See here,
  http://download.Oracle.com/docs/CD/B10500_01/server.920/a96521/onlineredo.htm

  Archived redo log:

  Oracle Database allows you to save files to one or more destinations offline newspapers filled with repeat groups, known collectively as the archived redo log. An archived redo log file is a copy of one of the members of a group of redo log filled.

  See here,
  http://download.Oracle.com/docs/CD/B19306_01/server.102/b14231/archredo.htm

  Thank you

• Redo and Archives association Journal

  Hello
  I am curious about the redo file and archive log file association, is one to one or one to many? In other words, is a log of arc file does hold data to a single file or several files to redo?
  Or is the Group of redo of file association arc rather than redo the file to arc file?
  
  The size of the bow on my machine logs, sometimes exceeds much the size of a single file to roll forward and will sometimes well below the size.
  
  Thank you.

  natet wrote:
  Hello
  I am curious about the redo file and archive log file association, is one to one or one to many? In other words, is a log of arc file does hold data to a single file or several files to redo?
  Or is the Group of redo of file association arc rather than redo the file to arc file?

  The size of the bow on my machine logs, sometimes exceeds much the size of a single file to roll forward and will sometimes well below the size.

  Thank you.

  Files redo archive log means (as it may seem his name) again save file which has been archived. It's the same thing as a redo log file. Sometimes your databsae can have checkpoint and log change before redo log fills then you can get different sizes of archived redo log file. But this isn't more combination of a redo log file, it's just a copy of a redo log file

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  Hi KERRYYX,

  1. Did you the latest changes on the computer?
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  PC is Windows XP.  The server is Windows 2000.  I have administrative rights on both machines.

  On getting PC security event log do message "local computer, maybe not the files of the necessary registry information or message DLL to display messages from a remote computer" for all entries.  System and application logs do not receive messages

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