Why not use min_score with Elasticsearch?

Question

New to Elasticsearch. I am interested in only returning the most relevant docs and came across min_score. They say "Note, most times, this does not make much sense" but doesn't provide a reason. So, why does it not make sense to use min_score?

EDIT: What I really want to do is only return documents that have a higher than x "score". I have this:

data = {
        'min_score': 0.9,
        'query': {
            'match': {'field': 'michael brown'},
        }
    }

Is there a better alternative to the above so that it only returns the most relevant docs?

thx!

EDIT #2: I'm using minimum_should_match and it returns a 400 error:

"error": "SearchPhaseExecutionException[Failed to execute phase [query], all shards failed;"

data = {
        'query': {
            'match': {'keywords': 'michael brown'},
            'minimum_should_match': '90%',
        }
    }

Answer 1

I don't know if it's the best solution, but it works for me (java):

// "tiny" search to discover maxScore
// it is fast, because it returns only 1 item
SearchResponse response = client.prepareSearch(INDEX_NAME)
                        .setTypes(TYPE_NAME)
                        .setQuery(queryBuilder)
                        .setSize(1)
                        .execute()
                        .actionGet();

// get the maxScore and
// and set minScore = 70%
float maxScore = response.getHits().maxScore();
float minScore = maxScore * 0.7;

// second round with minimum score
SearchResponse response = client.prepareSearch(INDEX_NAME)
                        .setTypes(TYPE_NAME)
                        .setQuery(queryBuilder)
                        .setMinScore(minScore)
                        .execute()
                        .actionGet();

I search twice, but the first time it's fast because it returns only 1 item, then we can get the max_score

NOTE: minimum_should_match work different. If you have 4 queries, and you say minimum_should_match = 70%, it doesn't mean that item.score should be > 70%. It means that the item should match 70% of the queries, that is minimum 3/4 queries