Drupal 7 Solr 4 $query group by I'm beginner in Drupal 7 et Solr 4. I have $query and I want to do a group by category. How can I add 'group by' as a parameter to $query (DrupalSolrQueryInterface) ??
You can add custom parameters through hook_apachesolr_query_alter, eg

function MYMODULE_apachesolr_query_alter(DrupalSolrQueryInterface $query) {
  $query-&gt;addParam('group', 'true');
  // etc
}