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Thread: Pct_free

  1. #1
    Join Date
    Mar 2006
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    Charlotte, NC
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    Pct_free

    Hi,

    quick question.

    In a data warehouse DB, If i know that in any given table only insert operations happens, is it feasible to set pctfree to 0 to save some storage?

    I know depends on block size and row length there is a chance of row chaining. I am monitoring the table regularly. Also, want to see the comments about the same here.

    Thanks,
    Last edited by vnktummala; 11-11-2010 at 02:08 AM. Reason: typo
    Vijay Tummala

    Try hard to get what you like OR you will be forced to like what you get.

  2. #2
    Join Date
    May 2002
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    2,645
    Would work for updates too as long as changed value is no longer than the original. Seems like that setting wouldn't cause any problems.

  3. #3
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    Thanks Stecal.

    Thanks,
    Vijay Tummala

    Try hard to get what you like OR you will be forced to like what you get.

  4. #4
    Join Date
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    Quote Originally Posted by vnktummala View Post
    In a data warehouse DB, If i know that in any given table only insert operations happens, is it feasible to set pctfree to 0 to save some storage?

    I know depends on block size and row length there is a chance of row chaining. I am monitoring the table regularly. Also, want to see the comments about the same here.
    This is a very good analysis and I agree with Stecal comment.

    Building on such comment as well as in original analysis I would like to add that - in my experience - setting pct_free to values in between 5 and 10 brings to the table the best of both world, space saving and low percentaje of chained/migrated rows.

    Having said that, I've also seen DWH tables getting new columns as well as getting "special" update processes which caused horrendous results on the chained/migrated rows department.
    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.

  5. #5
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    Thanks Paul.

    Thanks,
    Vijay Tummala

    Try hard to get what you like OR you will be forced to like what you get.

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