title: Query multiple collections with different fields in solr
body: <p>Given the following (single core) query's:</p>
  
  <pre><code>http://localhost/solr/a/select?indent=true&amp;q=*:*&amp;rows=100&amp;start=0&amp;wt=json
  http://localhost/solr/b/select?indent=true&amp;q=*:*&amp;rows=100&amp;start=0&amp;wt=json
  </code></pre>
  
  <p>The first query returns "numFound":40000"
  The second query returns "numFound":10000"</p>
  
  <p>I tried putting these together by:</p>
  
  <pre><code>   http://localhost/solr/a/select?indent=true&amp;shards=localhost/solr/a,localhost/solr/b&amp;q=*:*&amp;rows=100&amp;start=0&amp;wt=json
  </code></pre>
  
  <p>Now I get "numFound":50000".
  The only problem is "a" has more columns than "b". So the multiple collections request only returns the values of a. </p>
  
  <p>Is it possible to query multiple collections with different fields? Or do they have to be the same? And how should I change my third url to get this result? </p>