title: Performance difference between VARCHAR2 to NUMBER
body: <p>If I query my DataBase (Oracle) with unique Index on multiple columns, Will there be any performance difference if I change one of the columns from VARCHAR2 to NUMBER?<br>
  If there is, is it <strong>significant</strong>? </p>
  
  <p>(It's varchar2 because I need '0' at the beginning but I can change it in the presentation layer in my app)</p>