lib/similar_models.rb in similar_models-0.2.0 vs lib/similar_models.rb in similar_models-0.2.1

@@ -23,17 +23,15 @@
         ).joins("INNER JOIN #{join_table} ON #{join_table}.#{foreign_key} = #{primary_key_ref}")
       end
 
       scope = self.class.select("#{table_name}.*, count(#{primary_key_ref}) AS #{as}_model_count").
         where.not(primary_key => self.id).order("#{as}_model_count DESC")
-      group_by_clause = primary_key
+      group_by_clause = self.class.column_names.map { |column| "#{table_name}.#{column}"}.join(', ')
 
       # if there is only one many-to-many association no need to use UNION sql syntax
       if association_scopes.one?
         scope.merge(association_scopes.first).group(group_by_clause)
       else
-        group_by_clause = self.class.column_names.join(', ')
-
         # see http://blog.ubersense.com/2013/09/27/tech-talk-unioning-scoped-queries-in-rails/
         scope.from("((#{association_scopes.map(&:to_sql).join(') UNION ALL (')})) AS #{table_name}").group(group_by_clause)
       end
     end