How to sort results based on term position in elasticsearch >= 5.5?

问题

Since _index is no longer available in Painless scripting, hence solutions which used to work via accessing term-offset from _index in script_score do not work any more such as one advised here: Scoring by term position in ElasticSearch?.

What's the preferred way to do this now?

Thanks much for your help!

来源：https://stackoverflow.com/questions/49304331/how-to-sort-results-based-on-term-position-in-elasticsearch-5-5