title: Is Changing IF EXIST(SELECT 1 FROM ) to IF EXIST(SELECT TOP 1 FROM ) has any side effects?
body: <p>I have an existing SP running on my production server. I have found some significant performance gain from <strong>changing</strong> <code>IF EXIST(SELECT 1 FROM )</code> to <code>IF EXIST(SELECT TOP 1 1 FROM )</code> and <code>IF NOT EXIST(SELECT 1 FROM )</code> to <code>IF NOT EXIST(SELECT TOP 1 1 FROM )</code>. The only difference is <strong>TOP</strong> 1 keyword. Just curious to know whether changing this has any side effect?</p>