title: FALSE and TRUE vs NULL and TRUE
body: <p>I have column with type <code>BOOLEAN</code></p>
  
  <p>At first (on <code>INSERT</code>), value would be always <code>FALSE</code>, only after may be updated   column as <code>TRUE</code></p>
  
  <p>So question is: make this column <code>NOT NULL DEFAULT FALSE</code>, or make this column <code>DEFAULT  NULL</code> and then update as <code>TRUE</code> (and if then also would be reversing update, set column <code>NULL</code> and not <code>FALSE</code> value, so in this case, never would be used <code>FALSE</code> value )</p>
  
  <p>Which choice will be better point of view performance and storage saving ?</p>