title: update index in Solr, error: required field in SolrSchema not found in DataConfig
body: <p>I'm trying to update my index, but I keep on getting the error:</p>
  
  <blockquote>
    <p>org.apache.solr.handler.dataimport.DataImporter
    verifyWithSchema INFO: UPC is a
    required field in SolrSchema . But not
    found in DataConfigfound in DataConfig</p>
  </blockquote>
  
  <p>I can't figure out why it's complainting, since:</p>
  
  <ol>
  <li>the first time I ran the import, it worked fine, and the only thing I changed was add a few fields (columns) to schema.xml</li>
  <li><p>the table I am querying indeed has a UPC column. Here is what my data-config.xml looks like:</p>
  
  <pre><code>&lt;dataConfig&gt;
    &lt;dataSource type="JdbcDataSource" 
        driver="com.mysql.jdbc.Driver"
        url="jdbc:mysql://localhost:3306/product" 
        user="root" 
        password="some_password"/&gt;
    &lt;document&gt;
      &lt;entity name="product" 
         query="select * from productdetails"&gt;
      &lt;/entity&gt;
    &lt;/document&gt;
   &lt;/dataConfig&gt;
  </code></pre></li>
  </ol>
  
  <p>But again, the interesting part is that the import worked a second ago, but fails on re-import. I'm hoping somebody has had this problem before. If not, maybe someone can suggest other things to check for?</p>