Home Forums Article Discussions Article Discussions by Author Discuss content posted by Dave62 What's the best way to count? RE: What's the best way to count?

  • December 27, 2012 at 6:43 am

    #1571848

    gkganeshbe (12/26/2012)

    Is there any performance difference in the below given three queries.

    Note: Col1 is NOT NULL column

    SELECT COUNT(*) FROM Sales.SalesOrderDetail;

    SELECT COUNT(Col1) FROM Sales.SalesOrderDetail;

    SELECT COUNT(0) FROM Sales.SalesOrderDetail;

    Good question. I ran all 3 of these statements as a batch substituting SalesOrderID for Col1 and displayed the estimated execution plan. The estimated plan showed the cost of each query to be the same at 33%.

    Just out of curiosity I then added Query 4 from the question and according to the estimated execution plan it is still the fastest. They all were equally accurate.