Why leave out the dynamic field 'random_*'

The schema.xml that comes with this module doesn't declare the random_* field compared to the default that comes when you download apachesolr. I guess you left that out, especially with the random_seed which is pretty hard to detect in the default_sorts() in Solr_Base_Query.php. However, with hook_apachesolor_modify_query, it's pretty easy to add a random sort order.

see http://lucene.apache.org/solr/api/org/apache/solr/schema/RandomSortField...

Note, the documents seem to be wrong, in my testing following works:

   <!-- goes in types -->
    <fieldType name="rand" class="solr.RandomSortField" indexed="true" /> 

  <!-- goes in fields -->
   <dynamicField name="random*" type="rand" indexed="true" stored="true"/>

Adding following to the url to test:

http://localhost:port/solr/select?q=whatever&morekeyshere&sort=random_127789 desc

And in php code:

function hook_apachesolr_modify_query(&$query, &$params, $caller) {
  if ($caller == 'whatever') {
    $seed = rand(1, 200);
    $params['qt'] = 'standard';
    $params['sort'] = 'random_'. $seed .' asc';
  }
}

This works pretty fine. I'm aware it's probably hard to implement this by default, but simply adding it to the schema.xml would be fine, so we don't need to alter it every time. This might go into documentation if anyone is looking for this sort of solution.