Pct_free
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Thread: Pct_free

  1. #1
    Join Date
    Mar 2006
    Location
    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 01:08 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
    Posts
    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
    Join Date
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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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    Ft. Lauderdale, FL
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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
    Join Date
    Mar 2006
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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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