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Thread: dirty buffers

  1. #1
    Join Date
    Jun 2000
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    Madrid, Spain
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    Hi

    Does anyone know if datafile can contain data that are not validated but are written to the datafile by DBWR because the data buffer is full?


    Cheers

  2. #2
    Join Date
    Aug 2000
    Posts
    236
    Pando,

    Of course it can. By validate, I take it that you mean "comitted".

    Ireespective of data bring comitted or not (the dirty buffer write que) DBWR writes them back to disk. If they are rolled back, data is reconstructed using the SCN and the RBS.

    The Oracle fast commit mechanism commits the data only in the redolog buffer and files.

    Nizar.

  3. #3
    Join Date
    Jun 2000
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    well I am just puzzled that in an instance failure the redo logs protects changes made to database buffers in memory that have not been written to the datafiles, what happen to those data which are not validated but written to the datafile in an instance failure? Since there arent any rollback or commit.

  4. #4
    Join Date
    Jun 2000
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    aps got it they will be rolled back since last checkpoint

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