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Thread: Scn

  1. #1
    Join Date
    Jan 2008
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    Scn

    Hi,

    Can one SCN comprise of multiple changes ? Say for example an Update statement is Changing 100 blocks. Does all these 100 blocks stamped with the single SCN (Assuming that no other transaction is modifying these 100 blocks )

    Regards
    Sunil

  2. #2
    Join Date
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    It all depends on when you commit.
    Are you talking about a large transaction? Oracle assigns every committed transaction a unique SCN.
    Pablo (Paul) Berzukov

    Author of Understanding Database Administration available at amazon and other bookstores.

    Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.

  3. #3
    Join Date
    Jan 2008
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    31
    Quote Originally Posted by PAVB
    It all depends on when you commit.
    Are you talking about a large transaction? Oracle assigns every committed transaction a unique SCN.

    As far as i know, SCN's are assigned for each and every change., commited or uncommmited.

    http://www.dbasupport.com/forums/sho...ghlight=SCN%2A

    If it is true that SCN is stamped irrespective of commit, i want to know if all the bocks modified are given the same SCN number (if not all, at least is it possible that few of the blocks get the same SCN ??)

  4. #4
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    All blocks included in the transaction are stamped with the very same SCN, remember SCN is there to signal a consisten state of the database.

    Assume a transaction is running, a new SCN is generated at the time Oracle writes to RBS, then Oracle writes the transaction -including SCN, to redo log and you know what it means, the transaction has been commited.

    If the transaction is not commited you are not gonna see any new SCN in the database.
    Pablo (Paul) Berzukov

    Author of Understanding Database Administration available at amazon and other bookstores.

    Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.

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