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Thread: Undo mechanism

  1. #1
    Join Date
    Nov 2004
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    Unanswered: Undo mechanism

    Hello all,

    I know that Oracle uses undo table spaces or rollback segments as its undo mechanism. what does Microsoft SQL Server use as its undo mechanism?

    Krz

  2. #2
    Join Date
    Jun 2003
    Location
    Ohio
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    Provided Answers: 1
    Nothing. SQL Server DBAs do not make mistakes. Only Oracl DBAs make mistakes.

    Really.

    Oh, all right. The transaction log. Modifications to the data are written to a transaction log before being committed to the database.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  3. #3
    Join Date
    Nov 2004
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    25
    Hi Blindman,

    Do you have a link online that I can have a look at that explains Microsoft SQL Server's undo mechanism in detail? And maybe some issues with this mechanism?

  4. #4
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    Just check out Books Online, installed with Microsoft Server.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  5. #5
    Join Date
    Nov 2002
    Location
    Jersey
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    10,322
    Quote Originally Posted by krz
    Hello all,

    I know that Oracle uses undo table spaces or rollback segments as its undo mechanism. what does Microsoft SQL Server use as its undo mechanism?

    Krz

    Are you talking about the redo logs? Which is what the sql server transaction logs afre...

    Never heard of UNDO in Oracle before...what version?
    Brett
    8-)

    It's a Great Day for America everybody!

    dbforums Yak CorralRadio 'Rita
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    I'm Good Once as I ever was

    The physical order of data in a database has no meaning.

  6. #6
    Join Date
    Nov 2002
    Location
    Jersey
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    ok...found it...

    http://www.akadia.com/services/ora_optimize_undo.html

    There is no sql server equivilant...you have to restore to a point in time

    Or...

    do this

    BEGIN TRAN

    sql statement

    Until you supply the COMMIT or ROLLBACK the transaction is stillactive and the changes are not applied...
    Brett
    8-)

    It's a Great Day for America everybody!

    dbforums Yak CorralRadio 'Rita
    dbForums Member List
    I'm Good Once as I ever was

    The physical order of data in a database has no meaning.

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