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Statistic update not working?

  • January 17, 2013 at 3:48 pm

    #269546

    Hi everyone,

    I am looking at the actual execution plan of a query, and it shows that an index seek returns 50K rows and it estimated that it would return 1 row. I updated the index statistics with FULLSCAN, but it still shows the same thing. Why is that? Thanks.

  • January 17, 2013 at 4:00 pm

    #1578504

    http://sqlinthewild.co.za/index.php/2009/09/22/estimated-rows-actual-rows-and-execution-count/

    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

  • January 17, 2013 at 4:20 pm

    #1578513

    Very interesting, thanks!

  • January 18, 2013 at 11:25 am

    #1578828

    Hi Gila,

    I don't think that this applies to my scenario. I have an index scan, which has an actual rows count of 50K, and an estimated count of 375 (I had said 1 before, that was wrong). It has an execution count of 1. It is followed by a compute scalar, a sort, and then a merge join where it is joined with the results of another index scan that returns over 116K rows. Here is an image of this part of the execution plan for your review. Thanks.

  • January 18, 2013 at 12:32 pm

    #1578849

    If you want an explanation, I need to see the plan, not a partially blacked out image of the plan.

    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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