0b4ac2b0_earch___the_Feature_Smackdown___Solr_4_7_0
[Feature] Joins [ElasticSearch 1.0] via has_children and top_children queries [Solr 4.7.0] 
It's not supported in distributed search. See LUCENE-3759.
Apache Solr vs ElasticSearch - the Feature Smackdown!
Solr 4.7.0