Execution Plan Arrows

So I have started working on getting more involved in the database development side of things with emphasis on slow queries that shouldn’t be.  It’s important to note that I’m still new to this part of the game as I really like to work more on the admin side of SQL but when you are a small shop you wear many hats.

While progressing through learning the ropes I’ve come to examining the estimated & actual execution plans of these queries.  Most of the time these will both be equal in the estimated and actual values returned as shown by the image below.




So when reading an execution plan I start right to left and start looking for really high cost operations especially SCANS or something like that.  I’ll look at the estimated vs actual values and take note and continue on. What I did not know was the arrows in the execution plan represent the row counts and that the thickness of them change and can be used to help find a bottle neck in the plan.

Essentially what I can now do is look and see if I have a thick arrow right before a high cost operation which could identify potential problems.  I had no clue.


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