Out-of-Date or Insufficient Statistics
Admittedly, having out-of-date or unavailable statistics is not as big a problem as it was “back in the day.” In SQL Server releases prior to 7.0, the first question asked when someone was complaining of poor performance was, “When did you last update statistics?” If the answer was “Huh?” we usually found the culprit.
With Auto-Update Statistics and Auto-Create Statistics features in SQL Server, this problem is not as prevalent as it used to be. If a query detects that statistics are out of date or missing, it automatically causes them to be updated or created and then optimizes the query plan based on the new statistics.
Note
If statistics are missing or out of date, the first running query that detects ...
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