 <p>The approach will not succeed, as you can search, but you cannot sort by a multivalued field. This pointed out in <a href="http://stackoverflow.com/questions/7845337/sorting-with-multivalued-field-in-solr">Sorting with Multivalued Field in Solr</a> and <a href="http://wiki.apache.org/solr/CommonQueryParameters#sort" rel="nofollow">written in Solr's Wiki</a></p> <blockquote> <p>Sorting can be done on the "score" of the document, or on any multiValued="false" indexed="true" field provided that field is either non-tokenized (ie: has no Analyzer) or uses an Analyzer that only produces a single Term (ie: uses the KeywordTokenizer)</p> </blockquote> <p><strong>Update</strong></p> <p>About the alternatives, as you point out that you need to find similar documents for one given ID, why not create a second core with a schema like</p> <pre class="lang-xml prettyprint-override"><code>&lt;fields&gt; &lt;field name="doc_id" type="int" indexed="true" stored="true" /&gt; &lt;field name="similar_to_id" type="int" indexed="true" stored="true" /&gt; &lt;field name="similarity" type="string" indexed="true" stored="true" /&gt; &lt;/fields&gt; &lt;types&gt; &lt;fieldType name="int" class="solr.TrieIntField"/&gt; &lt;fieldType name="string" class="solr.StrField" /&gt; &lt;/types&gt; </code></pre> <p>Then you could do a second query, after performing the actual search</p> <blockquote> <p>q=similar_to_id=42&amp;sort=similarity</p> </blockquote>