title: SOLR facet with prefix and filters
body: <p>I have a problem with using facet.</p>
  
  <p>I need autocomplete and for this I using facet:</p>
  
  <pre><code>http://localhost:8080/solr/select?q=*:*&amp;wt=json&amp;indent=on&amp;facet=on&amp;rows=0&amp;fq=filter:("30")  AND filter2:("1")&amp;facet.field=spell&amp;facet.prefix=g&amp;facet.limit=10&amp;facet.mincount=1
  </code></pre>
  
  <p>I am using facet because I need to add filters to query for example <strong>filter:("30")  AND filter2:("1")</strong></p>
  
  <p>When I have in index a few documents all working fine and fast but if I add a lot of documents into index this query working too slow or simply SOLR is not responding at this query.</p>
  
  <p>My schema.xml:</p>
  
  <pre><code>......
  &lt;fieldType name="textSpellShingle" class="solr.TextField" positionIncrementGap="100"&gt;
     &lt;analyzer&gt;
        &lt;tokenizer class="solr.StandardTokenizerFactory"/&gt;
        &lt;filter class="solr.LowerCaseFilterFactory"/&gt;
        &lt;filter class="solr.ShingleFilterFactory" maxShingleSize="4" outputUnigrams="true"/&gt;
        &lt;filter class="solr.RemoveDuplicatesTokenFilterFactory"/&gt;
     &lt;/analyzer&gt;
  &lt;/fieldType&gt;
  .....
  &lt;fields&gt;
     &lt;field name="id" type="string" indexed="true" stored="true" required="true"/&gt;
     &lt;field name="article" type="textSpellShingle" indexed="true" stored="false" multiValued="true"/&gt;
     &lt;field name="title" type="text_general" indexed="true" stored="true"/&gt;
     &lt;field name="filter" type="int" indexed="true" stored="true"/&gt;
     &lt;field name="filter2" type="int" indexed="true" stored="true"/&gt;
  &lt;/fields&gt;
  &lt;uniqueKey&gt;id&lt;/uniqueKey&gt;
  &lt;defaultSearchField&gt;article&lt;/defaultSearchField&gt;
  &lt;solrQueryParser defaultOperator="OR"/&gt;
  &lt;copyField source="article" dest="spell"/&gt;
  &lt;copyField source="title" dest="spell"/&gt;
  ....
  </code></pre>