title: Eclipse indexing - what do the various options do
body: <p>When you <code>right-click &gt; index</code> on a project there are a few options:</p>
  
  <ol>
  <li>Rebuild </li>
  <li>Freshen All Files</li>
  <li>Update with Modified Files</li>
  <li>Re-resolve Unresolved Includes</li>
  </ol>
  
  <p>I've been just hitting rebuild everytime but now I'm working on a huge project and can't afford to do that; when I modify a file, whether it's a .cpp or .h, I need to know which 'index' operation to do.</p>
  
  <p>For each of the 'index' options:   </p>
  
  <ol>
  <li>What does it <em>precisely</em> do?</li>
  <li>What is the cost (relative memory, CPU time)?</li>
  </ol>
  
  <p>Documentation from Eclipse would be helpful but already searched and didn't find any.</p>