title: SQL unique : manual check vs catch exception
body: <p>I'm working on a big database and i'm seeking for everything that can speed up the database. The question is : when you have an unique index on somes fields, what is the faster between make a select request to check if it's ok, or try it anyway and catch the exception if the entry already exists ?</p>
  
  <p>I made some researchs but nothing conclusive. Thanks.</p>