February 7, 2011 at 1:06 pm
Hi
On our website when someone views a members image we update a field called visits which is just a counter that shows how many times an image has been viewed.
The sql statement looks like this : -
update images set visits=visits+1 where (username=@username) AND (mykey=@mykey)
However I have noticed that looking at the execution plan a clustered index update is taking place which is taking up 86%.
Anyone know why this might be?
Thanks
Matt
February 7, 2011 at 1:21 pm
The "clustered index" is, for all intents and purposes, the table itself. I would expect that to the majority of the work on a simple update.
In other words, this is normal and expected.
You'll want to take a look at how clustered indexes work. If you'll be administering or performance tuning, you'll need to know about them.
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February 7, 2011 at 1:33 pm
Also be aware that the execution plan adds up to 100%, so something will take up resources. If you have the index on fields that the update can use, then the resource usage should be minimal.
February 8, 2011 at 7:31 am
Also, also, be cognizant of the fact that just becuase you have a high cost in an execution plan, doesn't mean that the process itself is very high cost. Execution plan costs are just estimates and do not represent measures that you can use to determine performance.
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February 8, 2011 at 8:47 am
Thanks for all your replies
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