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  1. #1
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    Feb 2015
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    Unanswered: DB2 10.5 Enable parallelism

    Hi,

    We want to enable parallelism in DB2 10.5.

    First I have enabled intra_Parallel to yes.

    And then dft_degree to ANY.

    I am confuse about parameter MAX_QUERY DEGREE, currently its set to 1.

    Should I change to more then 1?

  2. #2
    Join Date
    Apr 2012
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    Provided Answers: 18

  3. #3
    Join Date
    Feb 2015
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    DB2 10.5 Enable parallelism

    db2mor thank you for your reply.
    Actually in documentation both max_querydegree & DFT_degree are described as for parallel execution of query.

    My confusion is can I have to reset both the parameters or only DFT_degree parameter for executing query with parallel?

    If both the parameter are need to be set, then for example I want to execute every query with parallel 4, now then I need to change both the parameter to 4??
    Last edited by masheedullah; 04-22-15 at 16:16.

  4. #4
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    Apr 2012
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    Provided Answers: 18
    Be aware also the impact of the DB2_WORKLOAD registry variable on these settings.

    Study carefully again the doc pages for dft_degree, intra_parallel, max_querydegree.
    They seem clear to me. Perhaps translations into your native language are available from IBM.

    I suggest you use: dft_degree and max_querydegree both as -1 (notice the minus) and intra_parallel=1 and also that you prove the effect of these via benchmarking your workload.

    Normally it is best to let the optimizer work out what is the best parallelism for each query. You can limit the max degree of parallelism via max_querydegree if needed. Additionally if you prove that a specifc workload/statement has a measurable benefit from a specific degree of parallelism then your programmers can use the special register CURRENT DEGREE for that workload/statement which can be different from dft_querydegree.

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