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Bitmap icon in excution plan

Beantwortet Bitmap icon in excution plan

  • Freitag, 24. Februar 2012 13:36
     
     
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    hi

       Can any body explain me about Bitmap . In which situation qury optimizer prefer for Bitmap. How it is helpful?

    please explain with example

    Regards

    Vikas

    Regards Vikas Pathak

     

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  • Freitag, 24. Februar 2012 13:53
     
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    Hi,

    This operator is used in parellel execution plans to filter rows that cannot be joined between tables. It is useful for filtering out rows early to avoid passing them to the next operator. The optimizer uses it if there is a high selectivity on the key.It is normally used on star joins in Data Warehouses.

    There is a good MSDN article on BITMAP filtering here http://msdn.microsoft.com/en-us/library/bb522541.aspx

    Pete

    Peter Carter http://sqlserverdownanddirty.blogspot.com/




     
  • Dienstag, 28. Februar 2012 06:54
     
     
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    hi Pete carter

       Thanks for sujesting this link. This is realy very helpful . but in this article they doesnt mention defth about bitmap. I didnt understatnd their benifit. I mean why sql query optimizer prefer bitmap filter. What is the structure of bit map . how we can say it is faster?

    Regards

    Vikas

    Regards Vikas Pathak

     
  • Dienstag, 28. Februar 2012 06:55
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    http://sqlblog.com/blogs/paul_white/archive/2011/07/07/bitmap-magic.aspx

    Best Regards, Uri Dimant SQL Server MVP http://dimantdatabasesolutions.blogspot.com/ http://sqlblog.com/blogs/uri_dimant/