January 25, 2010 at 8:24 am
Hello all,
I have been trying to determine how to make certain select query's more efficient and looked at the execution plan of those queries but am confused by the statistics that I see. The plan shows the Select , Sort, and Clustered Index seek. What statistics should I be looking for when viewing the results of the execution plan?
There are different stats for each of the displayed components for instance Select shows Cache plan size and memory grant, but the sort and clustered index seek show statistics such as Estimated IO cost, and Estimated CPU cost. What is pertinent to determine the efficiency of the query?
Also what does it mean if there is an index seek versus an index scan?
I appreciate your comments.
Keith
January 25, 2010 at 9:01 am
Try this free ebook - http://www.red-gate.com/specials/Grant.htm
If after reading that you dont know , its not worth knowing 🙂
January 25, 2010 at 9:10 am
downloading now. I will be sure to read through this. Thanks.
January 25, 2010 at 9:19 am
You can also look here for the brief version http://sqlinthewild.co.za/index.php/category/sql-server/execution-plans/ Start with this one http://sqlinthewild.co.za/index.php/2007/08/20/reading-execution-plans/
Don't get too hung up on those costs. They are estimates and there are many things that can make them wrong.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
January 25, 2010 at 9:34 am
Very good info Gail. This does save a bit on time when compared to reading 181 pages of red gates free e book. Thanks.
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