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  1. #1
    Join Date
    May 2007
    Posts
    56

    Unanswered: (intra_parallel) = Yes

    I have couple instances in DB2 v7.1.0 and some in DB2 v8.2.9.
    I am in the process of upgrading the rest of them but all my old instances have (INTRA_PARALLEL) = YES.
    Reading http://www-128.ibm.com/developerwork...ex.html#design I noticed that this parameter will be better = YES if I am using DSS or DW systems which is not the case.

    In v7 this parameter seems to not have big impact since v7 doesn't have share memory pools like v8.
    I am having messages on my new v8 instances because shared sort heap and long term memory ....

    Should I change this parameter back to No? Do I need to change anything else (other related parameters)?

    Thanks

  2. #2
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    If you choose to leave the intra-partition parallelism enabled make sure that the application group memory is configured properly. You can find a detailed discussion here: http://www-1.ibm.com/support/entdocv...id=swg21179841

    (you may need to register at the IBM web site in order to access the link, but it is free.)

    However, enabling the intra-partition parallelism in OLTP systems is generally not recommended, because the overhead of workload distribution between subagents in most cases exceeds the benefits. You can check statement explain plans to see if your workload uses parallel execution at all.
    ---
    "It does not work" is not a valid problem statement.

  3. #3
    Join Date
    Jan 2007
    Location
    Jena, Germany
    Posts
    2,721
    You can also control with the CURRENT DEGREE special register for each session how much of the intra-partition parallelism will be exploited. So if you have a mixed workload, then this would be a way to control things through the application.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  4. #4
    Join Date
    May 2007
    Posts
    56

    Wink

    Quote Originally Posted by n_i
    If you choose to leave the intra-partition parallelism enabled make sure that the application group memory is configured properly. You can find a detailed discussion here: http://www-1.ibm.com/support/entdocv...id=swg21179841

    (you may need to register at the IBM web site in order to access the link, but it is free.)

    However, enabling the intra-partition parallelism in OLTP systems is generally not recommended, because the overhead of workload distribution between subagents in most cases exceeds the benefits. You can check statement explain plans to see if your workload uses parallel execution at all.
    Thanks for the LINK and the advice about OLTP and enabling this parameter. What really bugs me is the fact that in all old systems we had (and still have some in v7) all instances have this parameter set to YES and as far as I know none of those databases are DSS or DW type. They are pretty much accessed either Perl/Scripts or Powerbuiler applications where users pull data from or insert data into...but since DB2 v8 changed its memory structure, I am inclined to turn to NO and monitor the DB for while.
    I am working for this company for year so far and all DB2 instances were built by people no longer in the company so I am trying to understand why some things were defined this way.

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