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Thread: interview question perhaphs :-)

  1. 03-03-2003, 10:03 PM #11
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    grjohnson
    grjohnson is offline Senior Advisor
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    Yeah, I'm pretty sure hrishy is aware of what Chaining/Migration is and it's effects. The questions was more, Why was a pointer maintained in the original block. Hence the discussion.

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  2. 03-03-2003, 11:36 PM #12
    hrishy
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    Originally posted by grjohnson
    Another sign of a good DBA: Might not know the answer, but knows where to find it. Very important...

    This is perhaphs the number one skill that i would look for in any DBA

    regards
    Hrishy
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  3. 03-04-2003, 02:07 AM #13
    k.chithra
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    Yeah .

    I mistook it as a separate Q.(when row migration takes place)

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    K.Chithra
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  4. 03-04-2003, 02:09 AM #14
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    abhaysk
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    Re: interview question perhaphs :-)

    Originally posted by hrishy
    Hi

    2)when you have row migration why does oracle keep a pointer in the block to the row where it has moved now ?

    regards
    Hrishy
    I belive this reason cud be the one of the reasons....

    after Insert of data....a pointer pointing to memoray location is assinged to it.
    after deletion of data....the pointer is dropped and not actual data is deleted, as writing 0 on disk takes too much time & unnecesssary use of resources.....

    So if we think logically, and i AFAIK Oracle is wrriten in C to handle the memory allocation and deallocation part, Pointers to memory location can be assigned or dropped and can be updated but requires complex logic.......instead Pointer to Pointer wud be more flexible and easy....so when a row is migrated...a new pointer is assigned......

    Correct me if i am wrong.......

    Abhay.
    funky...

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

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  5. 03-04-2003, 09:09 PM #15
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    grjohnson
    grjohnson is offline Senior Advisor
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    Originally posted by k.chithra
    Yeah .

    I mistook it as a separate Q.(when row migration takes place)

    Cheers
    No worries... I do it sometimes as well, skim the question and then answer.
    OCP 8i, 9i DBA
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