using parallel in Index creation
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Thread: using parallel in Index creation

  1. #1
    Join Date
    Sep 2000
    Location
    Calcutta / Ahmedabad, India
    Posts
    137

    using parallel in Index creation

    Hi,

    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.

    Thanks
    Suvashish

  2. #2
    Join Date
    Sep 2000
    Location
    Sao Paulo,SP,Brazil, Earth, Milky Way
    Posts
    350
    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.

    Regards,

    Chiappa

  3. #3
    Join Date
    Jan 2003
    Location
    india
    Posts
    175
    hi,

    before indexing you can set the
    "sort_area_size"
    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 (eg.oracle 8i standard edition)
    will not support parallel dml.

    it will just ignore your parallel clause.



    - Raja

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