Matthew McGiffen never promised us there would be no math:
Before using values from the statistics, the Optimizer will check to see if the statistics are “stale”, i.e. the modification counter exceeds a given threshold. If it does, SQL will trigger a resampling of the statistics before going on to form an execution plan. This means that the plan will be formed against up to date statistics for the table.
Read on for some experimentation on when stats updates kick in.
There will always be math! Who doesn’t love a good equation 🙂
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