title: Pentaho Kettle: changing meta at run-time
body: <p>I wonder if Kettle (AKA Pentaho PDI) supports metadata changing at run-time.</p>
  
  <p>I've implemented a couple of custom plugins:</p>
  
  <ul>
  <li>The first plugin sends data to the second plugin. The metadata of the rows sent in output can change when some conditions occur. In practice, this means that <code>processRow()</code> starts with a certain metadata and then, after a while, it changes it. Of course, the row sent in output through <code>putRow()</code> is always synchronized with the related metadata.</li>
  <li>The second plugin receives data from the first plugin, calling <code>getInputRowMeta()</code> for understanding the metadata of the received row. However, such metadata seems to not be synchronized with the received row.</li>
  </ul>
  
  <p>Given the results of this simple example, I wonder if the Kettle engine supports this kind of run-time behavior --- i.e. if <code>getInputRowMeta()</code> returns the correct metadata for the specific row that has been received.</p>
  
  <p>Is anybody able of providing evidence that metadata changing is actually not possible ? Otherwise, is there any safe way for getting the metadata of the specific row received in <code>processRow()</code> ?</p>