Field elevation in elastics search with django-haystack

Question

We are trying to implement field enhancement in Elasticsearch using Django Haystack 2.1.0 and pyelasticsearch 0.6. If I curl -XGET "http://localhost:9200/_mapping?pretty=true , I get a response (extraneous parts removed)

 { "haystack" : { "modelresult" : { "_boost" : { "name" : "boost", "null_value" : 1.0 }, "properties" : { "headline" : { "type" : "string", "boost" : 1.5, "analyzer" : "snowball", "store" : "yes", "term_vector" : "with_positions_offsets" }, } } } 

While we are trying to raise the header field. Even when using something absurd, such as 5000, does not affect the output. Is something missing?