Not sure if this solution will work for you but this is what I did to implement nested grouping using SOLR 3.X.
Simple idea behind is to Concatenate 2 fields and index them in to single field and group on that field.. http://stackoverflow.com/questions/12202023/field-collapsing-grouping-how-to-make-solr-return-intersection-of-2-resultse -- View this message in context: http://lucene.472066.n3.nabble.com/Group-by-multiple-fields-tp4068518p4068638.html Sent from the Solr - User mailing list archive at Nabble.com.
