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Question: Max degree of parallelization options seem to be ignored

  • November 20, 2017 at 8:23 am

    #329623

    Hi there,

    I have adjusted the option "Max degree of parallelization" multiple times on many servers.
    Despite that I have come across many instances where this option seems to be ignored, i.e. there are many more processes with the same PID and the resulting CXPACKET waits.

    Is there something I'm missing?
    What gives?

    Thank you very much and kind regards,

    Mark

  • November 20, 2017 at 8:35 am

    #1968788

    Max DOP = maximum number of concurrently *executing* threads for a single query. Not the maximum number of threads.
    eg, for a query under maxdop 4, there will be a minimum of 5 threads, the 4 executing threads and a controller that's just waiting for them all to be done. There will likely be more threads that are not running.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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