January 23, 2006 at 4:48 am
What exactly are the units of measure of CPU cost and IO cost with regard to the execution plan for a query.
I have been looking at SQL2000 VS SQL2005 and notice that an Index Seek on SQL2000 is roughly twice as costly as the SQL2005 version.
Can such a direct comparison be made safely?
January 23, 2006 at 5:04 am
It is the no of reads and writes that are counted as the cost
January 23, 2006 at 5:18 am
How can I have 0.00632 reads and writes?
January 24, 2006 at 2:46 am
I have asked this before and never found an answer that satisfies. The best I got was from an MVP who said that essentially they are abstract and can only be used to compare plans on the same machine with the same configuration and state. I just hope there is a better answer.
January 24, 2006 at 3:24 am
Joe Chang has written a couple of fairly advanced articles where he discuss costs (amongst other things). Take a look at the SQL Server Performance site, or just google it. They are not completely abstract, there are formulas that calculate them. And some of the formulas have definitely changed in 2005, so I do not think a comparison is valid.
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