Depending on how your index is parametrized, you shall get strange results. Be aware that Elasticsearch is basically a reverted index. Which means that values to be compared are indexed, analysed, stemmed... And therefore, if you want to compare exact not analysed values, you should have somewhere in your index not_analyzed values.

Refer to Elasticsearch documentation to get an idea of how to do this. A good idea would be to have a template to have all string values to be multi-field for example.

As you can guess, rescoring the whole bunch of documents can be very long and not very high-performing. My advice is to reduce the number of docs to rescore, by using the right query. The match all query used in examples is just... an example.