title: Does Solr support group multiple fields?
body: <p>I am newer to solr, we want to get document list of each group that grouped by multi-fields. And I finds solr supports grouping-result, but this feature supports just one field. And I also finds ReduceStream support multiple-fields, but the results set of ReduceStream are not like group-format. The parallel Sql feature can group by multi-fields, but cat not get document list of each group. My question is that: is there any ways to group result by multiple fields and the result set show as grouping-result feature.</p>
  
  <pre><code>Any help will be appreciated.
  </code></pre>
  
  <p>Note：I want to get document list of each group not the aggregation of each group, so facet.pivot, RollupStream etc can not match my question.
  And I find that ElasticSearch can statify my question by using terms aggregation(child aggregation) and top-hints metric aggregation.</p>