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Thread: using parallel in Index creation

  1. #1
    Join Date
    Sep 2000
    Calcutta / Ahmedabad, India

    using parallel in Index creation


    Creating an index on one of my large tables takes me arounf 2 Hours.

    If i create the index using Parallel 8 which will of course reduce the index creation time, and then later on once the index has been created , say i reset it back to NOPARALLEL, will there be any problem in data fetch later on. i mean any unforseen problem in future ? for ex, the standard queries might not use the index etc. etc. ?

    is it safe ? because i will be doing it on the Production database.


  2. #2
    Join Date
    Sep 2000
    Sao Paulo,SP,Brazil, Earth, Milky Way
    Some comments :

    a) your affirmation "using parallel 8 which will ** of course ** reduce the index creation time..." is NOT necessarily true : see, parallel means "I have unused resources at the moment (CPUs, memory, I/O bandwith) , and I want to have various processes doing a part of the big job each one". OF COURSE, each process WILL consume CPU, RAM & I/O, *** so *** if right now you DONīT have available resources in the machine, having even MORE processes running WILL slow you in a BIG way.

    b) yes, it is safe to do it in production, I always do using PARALLEL (and NOLOGGING, for the matter) , no probs.



  3. #3
    Join Date
    Jan 2003

    before indexing you can set the
    parameter to a higher value.

    oracle will use this area for sorting while indexing.

    once your indexing is over then reduce it back.

    some version of oracle ( 8i standard edition)
    will not support parallel dml.

    it will just ignore your parallel clause.

    - Raja

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