May 26, 2011 at 8:13 am
Okay, they are not exactly the same, but aside from a percentage one way or another, I have 2 execution plans that, at first glance, are almost identical.
There is a very pronounced performance difference between both queries, though. My question is, when you have two almost identical execution plans, what plan parts do you look at to figure out the bottleneck?
Thoughts?
May 26, 2011 at 8:19 am
estimate vs actual.
Optimization level (early terminaison reason)
May 26, 2011 at 8:38 am
Post em?
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
May 26, 2011 at 8:55 am
I'm looking at estimated plans right now, so I suppose the first thing to do is get the actual plans. Verify the information is still the same at that point.
May 26, 2011 at 8:56 am
Yup. The operators should be the same, the additional data on actual row count is the most useful .
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
May 27, 2011 at 4:25 am
Everyone has hit a lot of the highlights, I especially like checking the SELECT operator properties to see the compile & runtime values on params & the reason for early termination. After that, it's the long slog of digging into the details on the operators to see what variations might result in the differences.
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