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  1. #1
    Join Date
    Feb 2004
    Posts
    12

    Unanswered: some doubt about the CKPT background process

    In oracle's pdf,
    The Checkpoint Process (CKPT) is responsible for updating database status
    information in the control files and data files whenever changes in the buffer cache
    are permanently recorded in the database.

    I don't understand what kind of infomation can be called database status information, Can anyone give an example ?
    And why the database status information should be updated after the data was permanently recorded in the database ?

  2. #2
    Join Date
    Oct 2003
    Location
    Slovakia
    Posts
    482

    Re: some doubt about the CKPT background process

    Originally posted by viduka
    In oracle's pdf,
    The Checkpoint Process (CKPT) is responsible for updating database status
    information in the control files and data files whenever changes in the buffer cache
    are permanently recorded in the database.

    I don't understand what kind of infomation can be called database status information, Can anyone give an example ?
    And why the database status information should be updated after the data was permanently recorded in the database ?
    "I don't understand what kind of infomation can be called database status information, Can anyone give an example ?"

    Answer is SCN - System Change Number. The SCN is a number that identifies each change to the database. The SCNs are used during the checkpoint process, recovery process, and during point-in-time recovery.

    The CKPT process fires the DBWn to write data from buffer cache down to the disk. Then CKPT updates the datafile headers, control files and also log files according the change.It's a state synchronizer which maintain DB consistency.

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