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3 Replies Latest reply: Sep 15, 2013 11:36 PM by JohnWatson RSS

ASSM and multiple inserts

Sekar_BLUE4EVER Newbie
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Hi,

  When I am using ASSM and I am doing multiple inserts into the table does each session obtain a different block from the  bitmap and  insert into it or does all the session insert into the same block?

  • 1. Re: ASSM and multiple inserts
    Aman.... Oracle ACE
    Currently Being Moderated

    Sekar_BLUE4EVER wrote:

     

    Hi,

      When I am using ASSM and I am doing multiple inserts into the table does each session obtain a different block from the  bitmap and  insert into it or does all the session insert into the same block?

    It's not mandatory that each unique session would get a unique block only for the insertions. If one block still has the ITL slots available, it would be able to serve multiple session's inserts without any issues. The use of ASSM would relieve the contention from the segment's header block as that would be in severe contention when used with the Free lists .

     

    HTH

    Aman....

  • 2. Re: ASSM and multiple inserts
    Sekar_BLUE4EVER Newbie
    Currently Being Moderated

    What happens in case of RAC?Ideally it must use different blocks even if ITL slots are available otherwise we would run into unnecessary inter instance traffic right?

  • 3. Re: ASSM and multiple inserts
    JohnWatson Guru
    Currently Being Moderated

    MY understanding of the ASSM bitmap model is that  hash of your process ID is used to determine which branch of the bitmap you search, thus eliminating contention between sessions. RAC includes the instance ID in the algorithm, thus eliminating contention between instances. So in an ideal world, your concurrent inserts will go into different blocks.

    This was discussed a year ago here, Re: Locally Managed Tablespaces vrs ASSM

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