title: Solr morelikethis returns no documents
body: <p>I try to build a product recommender using the Text from the productdescription as input for recommendations.</p>
  
  <p>But for some reasons I don't get any results. I setup the productdescription as textfield in the Schema.XML . I also marked it as a vector field. </p>
  
  <p>My query looks like this <code>select?q=id:189&amp;mlt=true&amp;mlt.fl=productdescription&amp;mlt.mintf=1&amp;mlt.mindf=0</code></p>
  
  <p>From my understanding this query should somehow alsways bring me some similar items even if the score would be very low as df is set to 0. </p>
  
  <p>But the only result I get is sometimes a duplicate of a product with the same description but an different ID (the dataset is not perfect). </p>
  
  <p>So my question is: how can I always get the next nearest document even if there is no 1:1 match from the whole Text </p>