title: Is there a way to add extra metadata for Spark dataframes?
body: <p>Is it possible to add extra meta data to <code>DataFrame</code>s?</p>
  
  <h2>Reason</h2>
  
  <p>I have Spark <code>DataFrame</code>s for which I need to keep extra information. Example: A <code>DataFrame</code>, for which I want to "remember" the highest used index in an Integer id column.</p>
  
  <h2>Current solution</h2>
  
  <p>I use a separate <code>DataFrame</code> to store this information. Of course, keeping this information separately is tedious and error-prone.</p>
  
  <p><strong>Is there a better solution to store such extra information on <code>DataFrame</code>s?</strong></p>