title: Defining optimal varchar length
body: <p>I have found that there is no difference  between <strong>varchar(20)</strong> and <strong>varchar(40)</strong> in sense of performance.</p>
  
  <p>But then I asked myself logically question, why don't create a table where all character columns will be <strong>varchar(4000)</strong>?</p>
  
  <p>In my opinion, I think there exists some distinction between <strong>varchar(3)</strong> and <strong>varchar(4000)</strong> if my column contains only 3 character. But I can't find that distinction.</p>