June 14, 2013 at 5:58 am
Hi,
I hope you pro's could help me out with some performance issues I'm having..
Oke, so we have some performance issues, I looked into some blogs of Brent Ozar regarding the use of Performance Monitor to do some monitoring, helped me out a lot. Next what I wanted to do was use SQL Profiler to see what was going on. I know how to use profiler and understand all the terminology, but.... what are the threshold values for the data columns like CPU, reads, writes etc. I know that the duration depends on what the business considers slow. But have no idea at what I am looking for when checking the rest of the data values....What is considered bad and good?
I've searched every where, but can't find the answer for my question... If someone could help me or give me some pointers I would be really thankfull.
Cheers SQL D.
June 14, 2013 at 6:00 am
I don't think there is a good or bad. It depends on your queries.
This is why creating benchmarks is so important. Then you have something to compare your profiler results to.
June 14, 2013 at 6:07 am
Thanks for the fast reply. So what you're saying basically is monitoring and tracing when performance is ok, then comparing with the trace when it's not performing as it should?
June 14, 2013 at 6:12 am
Yes - More or less.
Have a look here, might help you
June 14, 2013 at 6:14 am
There's no magic threshold where below that it's fine and above that it's bad. There's only normal for your system and abnormal for your system.
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
June 14, 2013 at 6:22 am
Oke, i'm reading the article part 1 and 2, after I'm done I'll continue my Q : )
But then my next Q; What is considered normal and abnormal?
What do you look for when using profiler? Which data columns e.g. shows you ... oke wait something is bad there..?
I know that duration is for queries that are for e.g. running slow or finding deadlocks and locks etc, i know all about that... but the rest....pfff... I think I'm starting to loose it ...:(
June 14, 2013 at 6:25 am
If you have a query that takes 10 hours to execute, that doesn't necessarily mean that it's slow - It could be normal for your system.
There is no set in stone threshold for what's good and what's bad - It depends on your system, you need to know what is abnormal/normal for your system.
Read those articles, it will show you which columns to look out for.
June 14, 2013 at 6:30 am
sqldkay (6/14/2013)
But then my next Q; What is considered normal and abnormal?
Normal = normal for your system
Abnormal = not normal for your system.
If a query runs normally 2 minutes and is running 25 minutes today, that's abnormal.
If a query runs normally 2 minutes and is running 5 seconds today, that's also abnormal.
Right at this moment, I'm tuning a query that's running on average 50ms. I'm tuning it because it runs around 250000 times an hour and is normally under 10ms.
What do you look for when using profiler? Which data columns e.g. shows you ... oke wait something is bad there..?
By themselves, none of them.
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
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