http://ift.tt/1RF04il
In this article, I'll provide the hard-coded guesses that the optimizer uses with the optimize-for-unknown technique so that at least you know what the optimizer guesses it doesn't know. Good query tuning, in great part, starts with being able to explain cardinality estimations—especially ones that are inaccurate.
from SQL Server Pro http://ift.tt/1kCjeYg
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