Is there somewhere in the BOL that I can find out what are acceptable
numbers when looking at I/O and CPU cost when running the estimated
execution plan in Query Analyzer.
Thanks,
`BenThis is a multi-part message in MIME format.
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Hi Ben,
I don't know that I would classify these 'costs' as those that are =acceptable or unacceptable as you might look at PerfMon counters for =instance. These values are assigned by SQL Query Optimizer as it =generates possible plans, and decides which plan is more efficient. A =long time ago I think that these numbers had particular significance =relative to a specific test system, but as hardware has changed over the =years, they really aren't hard cost values any more. Suffice it to say =that the higher the IO cost the more disk IOs might be necessary, and =the higher the CPU cost, the more CPU cycles may be required. Their =values aren't particularly interesting otherwise... Keep in mind too =that simply because the optimizer decided on that particular plan, it =has probably also considered many others, and decided that the one you =see is optimal, given the current environment on your server.
I hope that helps. If you are trying to tune a particular query, I =would recommend running a workload through the Index Tuning Wizard to =see what that churns out. Otherwise, let the group know what your =tuning delimma is, and perhaps someone can help.
Thanks,
Ryan Stonecipher
Microsoft SQL Server Storage Engine
<Ben M> wrote in message news:erYTeTOxDHA.1856@.TK2MSFTNGP09.phx.gbl...
Is there somewhere in the BOL that I can find out what are acceptable numbers when looking at I/O and CPU cost when running the estimated execution plan in Query Analyzer.
Thanks,
`Ben
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Hi Ben,
I don't know that I would classify these 'costs' as =those that are acceptable or unacceptable as you might look at PerfMon counters for =instance. These values are assigned by SQL Query Optimizer as it =generates possible plans, and decides which plan is more efficient. A long =time ago I think that these numbers had particular significance relative to a =specific test system, but as hardware has changed over the years, they really =aren't hard cost values any more. Suffice it to say that the higher the IO =cost the more disk IOs might be necessary, and the higher the CPU cost, the more =CPU cycles may be required. Their values aren't particularly =interesting otherwise... Keep in mind too that simply because the optimizer =decided on that particular plan, it has probably also considered many others, and =decided that the one you see is optimal, given the current environment on your server.
I hope that helps. If you are trying to tune a =particular query, I would recommend running a workload through the Index =Tuning Wizard to see what that churns out. Otherwise, let the group know =what your tuning delimma is, and perhaps someone can help.
Thanks,
Ryan Stonecipher
Microsoft SQL Server Storage Engine
wrote in message news:erYTeTOxDHA.1856=@.TK2MSFTNGP09.phx.gbl...
Is there somewhere in the BOL that I can find out what are acceptable =numbers when looking at I/O and CPU cost when running the estimated =execution plan in Query =Analyzer.Thanks,`Ben
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