title: How to update solr index?
body: <p>When the user creates a document, I add the date to the solr index. Every time the data changes like edit or delete, do I have to reindex the whole data?</p>
  
  <p>What does reindex mean in that case? When I do</p>
  
  <pre><code>$this-&gt;indexData(array(
          'id' =&gt; $pid,
          'title' =&gt; $data['titel']
  ));
  </code></pre>
  
  <p>for each document and do <code>$solr-&gt;addDocuments</code>, does it just overwrite already existing data?</p>
  
  <p>I tried to reindex the whole index on add/delete/edit but after I delete a certain field its information still seems to be in the index.</p>
  
  <p>Any ideas?</p>