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How do you measure query execution time?
One simplistic approach to measuring the “elapsed time” between events is to just grab the current date and time. SELECT GETDATE(); SELECT /* query one */ 1 ; SELECT GETDATE(); SELECT /* query two */ 2 ; SELECT GETDATE();
How do you compare query performances?
To compare execution plans in Query Store
- In Query Store, identify a query that has more than one execution plan.
- Use a combination of the SHIFT key and your mouse to select two plans for the same query.
- Use the button Compare the plans for the select query in a separate window to start plan comparison.
How do I find the difference between two rows in SQL Server?
In the blue text, you can see the calculation of the SQL delta between two rows. To calculate a difference, you need a pair of records; those two records are “the current record” and “the previous year’s record”. You obtain this record using the LAG() window function.
What’s the difference between average and maximum execution times?
The skew is the difference between the average and maximum execution times for the step. You might want to investigate a step if two conditions are both true. One condition is that the maximum execution time is consistently more than twice the average execution time over multiple runs of the query.
What do the timeline and execution time views show?
The Timeline view shows the sequence in which the actual steps of the query are executed. The Execution time view shows the time taken for every step of the query. It can be used to understand what steps are taking longer to complete. Each view shows Avg time and Max time .
Where to find the details of a query?
Choose the Query identifier in the list to display Query details. The Query details page includes Query details and Query plan tabs with metrics about the query. You can also navigate to the Query details page from a Cluster details page, Query history tab when you drill down into a query in a Query runtime graph.
How does SQL Server discard a query plan?
Instructs the SQL Server Database Engine to discard the plan generated for the query after it executes, forcing the query optimizer to recompile a query plan the next time the same query is executed. Without specifying RECOMPILE, the Database Engine caches query plans and reuses them.