use own haystack backend

[jochengcd]

Collecting some pointers on implementing own ones haystack backend with additional functionality, we might can extend our own one that I added. All would need updating to current haystack and to be based on / working with ES7Backend.

somehow the base for all other modifications (involves custom_scores and nestedness)
django-haystack/django-haystack#804
https://gist.github.com/aolieman/7929274

the one I based our version on:
https://github.com/tehamalab/django-haystack-es/tree/master
we use
Allows query-time fields boosting
Allows query-time negative boost
might want to also use
multi-fields to be able to sort on titles

a basic multi_match query
https://stackoverflow.com/questions/27802628/search-for-multiple-words-elasticsearch-haystack

custom Haystack Elasticsearch backend with function_score and percolator support
https://gist.github.com/ricardosasilva/6823461110f3765c89e9

raw ES queries:
django-haystack/django-haystack#927
https://github.com/Jiydam/haystack-elasticsearch-raw-query

https://github.com/bennylope/elasticstack