SQL Server Query Optimizer Time Spent and Numbers

Question

In Microsoft SQL Server, is it possible to find how much time the query optimizer spent to generate N numbers of execution plans? (Let's say for a specific stored procedure).

Also, is it possible to know how many execution plans the query optimizer generated and which execution plan it has selected for that specific stored procedure?

Or does the query optimizer completely works like a sealed box?

Thanks!

Answer 1

Yes, SQL Server can report how long it took to do any of those actions (though you may have to run it to get some additional details such as actual row counts returned)

Statistics Time

SET STATISTICS TIME { ON | OFF }

• Displays the number of milliseconds required to parse, compile, and execute each statement. https://msdn.microsoft.com/en-us/library/ms190287.aspx

Execution Plans

To pull the execution plan you have many options:

• Query the plan cache: (https://www.mssqltips.com/sqlservertip/1661/analyzing-the-sql-server-plan-cache/)
• Trace/extended events the xml: https://www.mssqltips.com/sqlservertip/1264/capturing-graphical-query-plans-with-sql-server-profiler/)

• Gather it in SSMS: via the "Include Actual Execution Plan" button in the toolbar https://msdn.microsoft.com/en-us/library/ms189562.aspx

  • On the SQL Server Management Studio toolbar, click Database Engine Query. You can also open an existing query and display the estimated execution plan by clicking the Open File toolbar button and locating the existing query.

  • Enter the query for which you would like to display the actual execution plan.

  • On the Query menu, click Include Actual Execution Plan or click the Include Actual Execution Plan toolbar button

  • Execute the query by clicking the Execute toolbar button. The plan used by the query optimizer is displayed on the Execution Plan tab in the results pane. Pause the mouse over the logical and physical operators to view the description and properties of the operators in the displayed ToolTip.

  • Alternatively, you can view operator properties in the Properties window. If Properties is not visible, right-click an operator and select Properties. Select an operator to view its properties.

  • You can alter the display of the execution plan by right-clicking the execution plan and selecting Zoom In, Zoom Out, Custom Zoom, or Zoom to Fit. Zoom In and Zoom Out allow you to zoom in or out on the execution plan, while Custom Zoom allows you to define your own zoom, such as zooming at 80 percent. Zoom to Fit magnifies the execution plan to fit the result pane.