When does SQL Server warn about an Excessive Memory Grant?

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17















What are the conditions that produce an "Excessive Grant" execution plan warning?




The query memory grant detected "ExcessiveGrant", which may impact the reliability. Grant size: Initial 5128 KB, Final 5128 KB, Used 16 KB.




SSMS



SSMS plan



SSMS properties



Plan Explorer



Plan Explorer



Showplan xml



<Warnings>
<MemoryGrantWarning GrantWarningKind="Excessive Grant"
RequestedMemory="5128" GrantedMemory="5128" MaxUsedMemory="16" />
</Warnings>









share|improve this question


























    17















    What are the conditions that produce an "Excessive Grant" execution plan warning?




    The query memory grant detected "ExcessiveGrant", which may impact the reliability. Grant size: Initial 5128 KB, Final 5128 KB, Used 16 KB.




    SSMS



    SSMS plan



    SSMS properties



    Plan Explorer



    Plan Explorer



    Showplan xml



    <Warnings>
    <MemoryGrantWarning GrantWarningKind="Excessive Grant"
    RequestedMemory="5128" GrantedMemory="5128" MaxUsedMemory="16" />
    </Warnings>









    share|improve this question
























      17












      17








      17


      1






      What are the conditions that produce an "Excessive Grant" execution plan warning?




      The query memory grant detected "ExcessiveGrant", which may impact the reliability. Grant size: Initial 5128 KB, Final 5128 KB, Used 16 KB.




      SSMS



      SSMS plan



      SSMS properties



      Plan Explorer



      Plan Explorer



      Showplan xml



      <Warnings>
      <MemoryGrantWarning GrantWarningKind="Excessive Grant"
      RequestedMemory="5128" GrantedMemory="5128" MaxUsedMemory="16" />
      </Warnings>









      share|improve this question














      What are the conditions that produce an "Excessive Grant" execution plan warning?




      The query memory grant detected "ExcessiveGrant", which may impact the reliability. Grant size: Initial 5128 KB, Final 5128 KB, Used 16 KB.




      SSMS



      SSMS plan



      SSMS properties



      Plan Explorer



      Plan Explorer



      Showplan xml



      <Warnings>
      <MemoryGrantWarning GrantWarningKind="Excessive Grant"
      RequestedMemory="5128" GrantedMemory="5128" MaxUsedMemory="16" />
      </Warnings>






      sql-server execution-plan warning memory-grant






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      asked Jan 28 at 12:15









      Paul WhitePaul White

      52k14278450




      52k14278450




















          1 Answer
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          19














          To produce this warning:



          1. The maximum used memory must be less than 5% of the granted memory; AND

          2. The query must use the regular (not small) resource semaphore

          To use the regular resource semaphore the query must:



          • Have granted memory over 5MB (5120 KB, 640 x 8KB pages); OR

          • Have a total estimated plan cost of over 3 units and not be a trivial plan

          Server version requirements:



          • SQL Server 2014 SP2 (12.0.5000) or later

          • SQL Server 2016 SP1 (13.0.4001) or later

          • SQL Server 2017 RTM (14.0.1000) or later





          share|improve this answer
























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            1 Answer
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            active

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            19














            To produce this warning:



            1. The maximum used memory must be less than 5% of the granted memory; AND

            2. The query must use the regular (not small) resource semaphore

            To use the regular resource semaphore the query must:



            • Have granted memory over 5MB (5120 KB, 640 x 8KB pages); OR

            • Have a total estimated plan cost of over 3 units and not be a trivial plan

            Server version requirements:



            • SQL Server 2014 SP2 (12.0.5000) or later

            • SQL Server 2016 SP1 (13.0.4001) or later

            • SQL Server 2017 RTM (14.0.1000) or later





            share|improve this answer





























              19














              To produce this warning:



              1. The maximum used memory must be less than 5% of the granted memory; AND

              2. The query must use the regular (not small) resource semaphore

              To use the regular resource semaphore the query must:



              • Have granted memory over 5MB (5120 KB, 640 x 8KB pages); OR

              • Have a total estimated plan cost of over 3 units and not be a trivial plan

              Server version requirements:



              • SQL Server 2014 SP2 (12.0.5000) or later

              • SQL Server 2016 SP1 (13.0.4001) or later

              • SQL Server 2017 RTM (14.0.1000) or later





              share|improve this answer



























                19












                19








                19







                To produce this warning:



                1. The maximum used memory must be less than 5% of the granted memory; AND

                2. The query must use the regular (not small) resource semaphore

                To use the regular resource semaphore the query must:



                • Have granted memory over 5MB (5120 KB, 640 x 8KB pages); OR

                • Have a total estimated plan cost of over 3 units and not be a trivial plan

                Server version requirements:



                • SQL Server 2014 SP2 (12.0.5000) or later

                • SQL Server 2016 SP1 (13.0.4001) or later

                • SQL Server 2017 RTM (14.0.1000) or later





                share|improve this answer















                To produce this warning:



                1. The maximum used memory must be less than 5% of the granted memory; AND

                2. The query must use the regular (not small) resource semaphore

                To use the regular resource semaphore the query must:



                • Have granted memory over 5MB (5120 KB, 640 x 8KB pages); OR

                • Have a total estimated plan cost of over 3 units and not be a trivial plan

                Server version requirements:



                • SQL Server 2014 SP2 (12.0.5000) or later

                • SQL Server 2016 SP1 (13.0.4001) or later

                • SQL Server 2017 RTM (14.0.1000) or later






                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Jan 31 at 9:21

























                answered Jan 28 at 12:15









                Paul WhitePaul White

                52k14278450




                52k14278450



























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