zzz

https://www.elastic.co/guide/en/elasticsearch/guide/current/_significant_terms_demo.html#_recommending_based_on_statistics

http://stackoverflow.com/questions/18199135/is-it-possible-to-left-join-nested-documents-in-elasticsearch-queries

http://stackoverflow.com/questions/21833092/elasticsearch-join-filter-using-subquery-results-as-filter-input-possible

https://www.elastic.co/guide/en/elasticsearch/guide/current/relations.html

https://www.elastic.co/guide/en/elasticsearch/guide/current/parent-child.html

https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-has-parent-query.html#query-dsl-has-parent-query

https://www.elastic.co/guide/en/elasticsearch/reference/2.1/query-dsl-filtered-query.html

https://www.elastic.co/guide/en/elasticsearch/guide/current/application-joins.html