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? Regarding the sys.dm_db_missing_index_group_stats

  • September 21, 2009 at 2:45 pm

    #210023

    I am trying to find the diff between the following, it seems that they are almost doing the same thing?

    #2 tells me that will reduce the cost of the sql query by x amount( 1000 mill * .50= 500 mill) 50 % improvement not sure if that is correct if so how does #1 differ?

    1. "avg_total_user_cost: Average cost of the user queries that could be

    reduced by the index in the group."

    2. "avg_user_impact: Average percentage benefit that user queries could

    experience if this missing index group was implemented. The value means

    that the query cost would on average drop by this percentage if this

    missing index group was implemented."

    THANKS

  • September 22, 2009 at 6:53 am

    #1056725

    Cost is how much the query costs, on average, to run. The user impact is how much of that cost is going to be saved or reduced. They're definately different numbers.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
    - Theodore Roosevelt

    Author of:
    SQL Server Execution Plans
    SQL Server Query Performance Tuning

  • September 22, 2009 at 8:51 am

    #1056848

    Thanks.....GRANT, that helped

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