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Thread: Maximum allowable extents

  1. #1
    Join Date
    Nov 2002
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    Question Maximum allowable extents

    (1) What is the ramifications to having the number of extents exceed the maximum allowable?

    (2) If the MAX_EXTENTS parameter value on a table was, previous regime, set to unlimited, can I set the MAX_EXTENTS value back to an acceptable value without any ramifications?


    I am running Oracle 7.3.2 on a SUN Enterprise 4000 platform using Solaris 2.5.1 O/S. The db_block_size on my system is 8K; therefore, the maximum allowable extents is 505.

    Thanks in advance,

    Rod

  2. #2
    Join Date
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    1) Thye can not exceed the max allowed paramter. Use bigger extent sizes.

    2) Yes, the ramifications are that you will have less extents available.

    Are you sure about that 505 number, that does not sound accurate, although version 7 was before my time.

    MH
    I remember when this place was cool.

  3. #3
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    Consider what happens if you put a hard limit on the number o extents, say 1000.

    If a table or index attempts to get extent 1001, it will be unable to do so, and your database is effectively broken.

    Without the limit, you MAYBE have a VERY SLIGHT degradation in performance.

    I would say keep it at UNLIMITED, and just watch the number of extents. If it turns out that a segment has undersized extents then move/rebuild it to a tablespace with a larger default extent size.
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
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    Oracle ACE

  4. #4
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    Ok, now i'm confused but that is normal for me. Why not just specify the storage at the table level and use (or change to) larger next extent sizes, if they are too small.

    MH
    I remember when this place was cool.

  5. #5
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    many extents can also cause fragmentation, oracle recommends keeping the amount of extents to a minimum.

    If no LMT then you have performance issues whenever another extent is required.
    Once you have eliminated all of the impossible,
    whatever remains however improbable,
    must be true.

  6. #6
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    Originally posted by Sureshy

    If no LMT then you have performance issues whenever another extent is required.
    There has been lot of debate on this issue. And Jmodic has shown that Number of extents will not matter in the degrade of Performance.

    Please search this site for that debate on No of extents.
    funky...

    "I Dont Want To Follow A Path, I would Rather Go Where There Is No Path And Leave A Trail."

    "Ego is the worst thing many have, try to overcome it & you will be the best, if not good, person on this earth"

  7. #7
    Join Date
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    Originally posted by Sureshy
    many extents can also cause fragmentation, oracle recommends keeping the amount of extents to a minimum.

    If no LMT then you have performance issues whenever another extent is required.
    Maybe this will make you change your opinion
    http://asktom.oracle.com/pls/ask/f?p...1092233274210,
    Last edited by patel_dil; 05-21-2003 at 12:10 PM.
    -- Dilip

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