title: select from select, performance
body: <p>I would like to ask, what query should be more efficient ?</p>
  
  <pre><code>select col1, col2 from 
      (select col1, col2 from table2) 
  where col1 = 'something'
  </code></pre>
  
  <p>or</p>
  
  <pre><code>select col1, col2 from 
      (select col1, col2 from table2 
      where col1 = 'something') 
  where col1 = 'something'
  </code></pre>
  
  <p>It seems that second query should by more efficient but in sqldeveloper first query takes less time. Why is it like that ?</p>