What is a redo log file? can anyone explain in simple terms

I am confused between redo log file and physical datafile can anyone explain in simple terms
Thank u
Regards,
Vijay

See Overview of Physical Database Structures

Similar Messages

  • Can anyone explain in simple terms how to set up icloud when I have 2 identities?

    I use my mac.com id for my calendar and contacts, but have a different ID for store purchases and everything else.  I would like to set up my iCloud with a single ID, but I don't want to lose all my historical calendar and contact data, so I need my iCloud tpo import the data from the Mobile.Me 'mac.com' account.
    Everything I have read is confusing....can anyone explain in simple terms how I sert the iCloud up?  I run a Macbook, a Windows 7 PC and an iphone, and I need them all to syns together.
    Any help appreciated.
    CliffWragg

    Welcome to the Apple Community.
    You can drag all your contacts (all at once) and each calendar from address book and iCal to your desktop as a back up/copy. Once you have set up iCloud using the ID for your apps, books and tunes etc, you can add the contacts and calendars to the new account by clicking on the desktop files, iCloud will sync them to your other devices.

  • What  is online redo log files???

    Dear All,
    I m bit confused with redo log files.what is need of back up of redo log files?????As i m new in the Basis please tell me i always get confused with redo log files and archive files.
    Thanx and reagard's
    Ashok

    In Oracle you have a number of online redo log files.
    In an typical SAP installation you have two directories:
    origlogA and origlogB
    origlogA contains online redo log 1 and 3 and
    origlogB contains online redo log 2 and 4.
    In most installation you also have mirrlogA and mirrlogB, which the name tells, is mirrors of origlogA and origlogB.
    Now, the online redo logs are circular,
    so when 1 gets full oracle jumps to number 2.
    At the same time oracle's archiver process starts to copy
    online redo log number 1 to a file on disk.
    This files are also known as archive redo logs.
    In an recovery situation you might do with just the online redo logs,
    but usually a combination of both online and archive redo logs is needed.
    During database backup, you also backup the online redo logs
    You also need to backup (backup twice then delete) archive redo logs.
    the archive redo logs are your way back from the restored database to the last transaction of the database.
    If one archive redo log is missing, you have to stop you recovery there and loose the rest of the transactions done in the database.

  • All My Files - can anyone explain it?

    In my AMF, I have the categories PDF Documents, Spreadsheets, Developer and Documents - in that order.  What use is that?
    Others seem to have Music, Movies, Photos, etc.
    How is AMF working, and is it definable in terms of what is shown?

    I'm completely confused by All My Files. I can't find anything except by searchng for the file name, which does me little good because I have thousands of files.
    I need to be able to see my old file tree. I had it organized exactly the way I wanted it and now everything is here there and everywhere with no apparent reason. Big trouble! I hope someone can explain it. Thanks.

  • Can anyone explain in simple steps how to download pdf file from my ipad (ibooks) to mac mavericks ( ibooks) please only workable solution should be displayed

    I would like to download my books and pdf file from my ipad ( ibooks) to my macbook pro (ibooks) both using the same icloud and  apple id.
    no joy and getting annoyed. Please help me

    Since the iTunes update 11.1.3 this should happen automatically!
    P. Bowden

  • What is Bearshare that is showing in search box with Firefox 4 download? Have been told in the past that it is a bad site!? Not a techie can anyone advise in simple terms?

    Don't know whether to use it?

    You need to get the owner's manual for your Ford's bluetooth system to see how to put your system into discovery mode for the iPhone as well as the appropriate steps to take. 
    In addition, you should see if the iPhone is supported.

  • How do I ensure that new iPhone becomes a separate entity to my husbands. Our current ones are named the same!! Annoying in terms of apps / contacts etc! Can anyone help in simple terms!

    Hi
    Have just changed my phone and network. Now have 5c.
    Previous I had 4s as does my husband.
    When he got his phone he connected it to our Apple Mac and from that point on
    Our phones became as one as he did not name his!!! This has been so
    Annoying in terms of apps and contacts appearing and disappearing!
    As it happens I don't have an iTunes library so can create that at later date.
    How do I seperate us now I have new phone ?
    Do I get a new apple ID or just name my phone or will it be ok now that we have
    different handsets?
    Please help I won't want his apps and music and he won't like girly stuff either!
    Thanks

    Hi janey73,
    Thanks for visiting Apple Support Communities.
    If you haven't already, you can create your own Apple ID on the web by following this link:
    My Apple ID
    https://appleid.apple.com
    You can also create an Apple ID using iTunes on a computer or iOS device. See this link for the step-by-step instructions:
    iTunes: How to set up an Apple ID within iTunes
    http://support.apple.com/kb/ht2731
    Once you have created your own Apple ID, you can sign out of the Apple services that are currently using your husband's Apple ID, and sign in with your own.
    This article has instructions for doing so with specific Apple services:
    Apple ID: What to do after you change your Apple ID
    http://support.apple.com/kb/HT5796
    Regards,
    Jeremy

  • Can anyone help (in simple terms please!)

    We have just tried to update iPad to iOS 7.1.1 and now have a screen showing the USB cable and iTunes. Have tried to reboot but hasn't solved the problem. I understand we need to connect to iTunes but we no longer have a laptop as only use the iPad (&iphone) what can we do??!

    iPad: Unable to update or restore
    http://support.apple.com/kb/ht4097
    iTunes: Specific update-and-restore error messages and advanced troubleshooting
    http://support.apple.com/kb/TS3694
    If you can’t update or restore your iOS device
    http://support.apple.com/kb/ht1808
     Cheers, Tom

  • HDV & FCP - Can anyone explain this in layman's terms??

    Okay, I have a broad but limited understanding of all these technical terms for HDV and FCP and I am still banging my head against the wall in frustration!!
    I make videos underwater for divers and the company I work for. I have just moved into the world of HDV and am using the Sony FX1 and FCP Studio.
    I have many areas I am looking for help in:
    1. After I have captured my footage to FCP and I pull clips from logged footage, ever clip that goes into the timeline needs rendering - 8 sec of footage takes 5-10min to render, this is before any effects!!! Does anyone know what could be the cause of this? I have checked and re-checked all my A/V settings, capture settings, etc. but still cannot figure out why every clip I drag to the timeline requires rendering.
    2. Footage I capture looks great as it's capturing but when I play it back in the viewer or Canvas it looks as though I've shot it during a heatwave - it sort of goes fuzzy then clear, fuzzy then clear - not terribly so, but enough to make me scream with frustration at the "not-so-nice" video
    3. Can anyone explain in simple terms how I downconvert a sequence before exporting for use in DVDSP 4? I am a little unfamiliar with Compressor and besides Compressor takes 8 hours to compress a simple 6min video!!!
    Has anyone else encountered these problems? Does anyone have any answers before I end up a drivelling wreck??

    I am at my wit's end trying to work out where I am going wrong. I have set FCP (5.0.2) to "Easy Setup" for my Sony FX1. The camera is set up as follows:
    IN/OUT REC
    VCR HDV/DV - HDV
    COMPONENT - 1080i/480i
    i.LINK CONV - OFF
    TV TYPE - 16:9
    A/V-DV OUT - OFF
    I have tried to log and capture footage three times now and every time I have to render simple clips taken from the Viewer into the Timeline. I haven't done any special effects, they are just plain old clips. Rendering a 7 second clip takes approx. 8min!! I can't move forward with my editing having to render every single clip I drag to the timeline.
    I have searched high and low for an answer to this problem but no one else seems to have this problem or has yet to come up with a solution! Can anyone please help me? This is driving me crazy!?

  • How to increase the size of Redo log files?

    Hi All,
    I have 10g R2 RAC on RHEL. As of now, i have 3 redo log files of 50MB size. i have used redo log size advisor by setting fast_start_mttr_target=1800 to check the optimal size of the redologs, it is showing 400MB. Now, i want to increase the size of redo log files. how to increase it?
    If we are supposed to do it on production, how to do?
    I found the following in one of the article....
    "The size of the redo log files can influence performance, because the behavior of the database writer and archiver processes depend on the redo log sizes. Generally, larger redo log files provide better performance, however it must balanced out with the expected recovery time.Undersized log files increase checkpoint activity and increase CPU usage."
    I did not understand the the point however it must balanced out with the expected recovery time in the above given paragraph.
    Can anybody help me?
    Thanks,
    Praveen.

    You dont have to shutdown the database before dropping redo log group but make sure you have atleast two other redo log groups. Also note that you cannot drop active redo log group.
    Here is nice link,
    http://www.idevelopment.info/data/Oracle/DBA_tips/Database_Administration/DBA_34.shtml
    And make sure you test this in test database first. Production should be touched only after you are really comfortable with this procedure.

  • Filled redo log files are available to LGWR for reuse

    Hi,
    Oracle version:
    Oracle Database 10g Release 10.2.0.4.0 -
    OS:Windows XP
    In oracle documentation it is mentioned that:
    Filled redo log files are available to LGWR for reuse depending on whether archiving is enabled.
    *> If archiving is disabled (the database is in NOARCHIVELOG mode), a filled redo log file is available after the changes recorded in it have been written to the datafiles*.
    Link for Documentation is:
    http://docs.oracle.com/cd/B28359_01/server.111/b28310/onlineredo001.htm
    My doubt is:
    Redo Records are written to datafiles also??

    user12141893 wrote:
    Does it mean:
    Suppose:
    Online redo log files contains some redo entries and database buffer cache contains some data and this data belong to redo entries of redo log files.
    Now this redo log file can't be reused until those (related) blocks of database buffer cache are written into datafiles.
    This is sort of correct. If the log file would be filled up , LGWR would switch over to the next log group and would initiate a Log Switch which would further trigger DBWR to start checkpointing the content protected by this log group to the data file. By the time this operation would be going on, the Log group's members would have the status of Active and once it would be complete, the status would be marked to Inactive which means that this log group and its members can be reused by LGWR.
    HTH
    Aman....

  • Can anyone explain me what is netweaver

    Hi All,
    what is netweaver....can anyone explain me..
    cheers,
    Raghavesh

    hi,
    just read this
    http://en.wikipedia.org/wiki/NetWeaver
    this is a basic explanation with all components
    Regards,
    michal
    <a href="/people/michal.krawczyk2/blog/2005/06/28/xipi-faq-frequently-asked-questions"><b>XI / PI FAQ - Frequently Asked Questions</b></a>

  • What is the difference between undo tablespace and online redo log files.

    what is the difference between undo tablespace and online redo log files. I am confused
    as per my knowledge undo tablespace is used to store the undo information when a table is being updated so that, just incase we need to rollback a transaction we know what was present in the table earlier.
    when a transaction fails the SMON performs the rollback of the data.
    This undo data is stored in the undo tablespace and read consistency if any is enforced.
    is my understanding till here correct?
    Now, can this undo data/before image not be stored in the redo log buffer and online redolog files?
    can redo-log files not store this information?
    in fact, is it that when undo tablespaces exist in a database, the undo data/before image is stored in both the undo tablespace and also the redo log files?
    kindly clarify my doubt.
    thank you.

    This question has been asked many times before. The answer is always the same.
    Yes, redo contains the before image of data (and the after-image). Therefore, it **COULD** be used to roll back a transaction.
    BUT... Redo is written sequentially. Using it to rollback your transaction would involve reading through all the redo written by maybe thousands of other people. It would be painfully slow.
    Your transaction is, however, directly linked to just the UNDO that it generates (which is JUST the before image of the data). So, your undo is your undo and doesn't share space with anyone else's undo. Therefore, using it to roll back YOUR transaction is fast.
    The fact that undo is only the before image of the data also makes it faster than wading through a sea of before and AFTER images as you'd find in redo. About twice as fast, in fact, since there's half the data. Roughly.
    Redo also gets written and flushed to disk whenever there's a commit, 3 seconds are up or too much (1MB, actually) redo gets generated between flushes caused by other factors. Your redo gets flushed when those things happen, even if you haven't actually committed your transaction. And redo logs recycle themselves, meaning that your redo -even if your transaction hasn't been committed yet- can be over-written by later transactions. Try rolling back when that's happened, if redo was the source of your rollback data!
    Undo, however, cannot be over-written if the transaction has not been committed. Ever. If you don't commit for three years, there will be three years' undo stored in your database (assuming you had the space, of course!).
    I could go on, but that will do. Redo is there fore RECOVERY, after catastrophe. Undo is there for read-consistency (and the occasional change of mind). Two different functions. Two different mechanisms. Each one highly tuned to doing what it does, why it does it, most efficiently and effectively.

  • What is the purpose of standby redo log files

    Hi,
    What is the purpose of the standby redo log files in DR?
    what if the standby redo log files are created? or else not created?
    Please explain
    Thanks

    3.1.3 Configure a Standby Redo LogA standby redo log is required for the maximum protection and maximum availability modes and the LGWR ASYNC transport mode is recommended for all databases. Data Guard can recover and apply more redo data from a standby redo log than from archived redo log files alone.
    You should plan the standby redo log configuration and create all required log groups and group members when you create the standby database. For increased availability, consider multiplexing the standby redo log files, similar to the way that online redo log files are multiplexed.>
    Reference http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/create_ps.htm#i1225703
    HTH
    Anand

  • What will happen when redo log file or archive log file, which is yet to be

    What will happen when redo log file or archive log file, which is yet to be read by logminer is corrupted? It seems that the captures process hangs between “Paused for flow control” and “Enqueuing Messages”. How to come out of this condition without recreating the captures process?
    Any clue is helpful
    Thanks in advance for your help.

    Basically you can't skip SCN since it will result in a data integrity issues (say you had skipped some inserts and later there will be some updates to a not replicated data).
    Streams maintain their own checkpoint tables with transaction related stuff. So there is no way you can jump over a range of SCN's without recreating capture.
    The only thing you can try - temporary give capture process a rule without any objects. But it will need to mine through the redo anyway.

Maybe you are looking for