elasticsearch multi_match vs should

Question

Can someone tell me the difference between

"query": {
    "bool": {
        "should": [
            { "match": {"title": keyword} },
            { "match": {"description": keyword} }
        ]
    }

and

"query": {
        "multi_match": {
            "query": keyword,
            "fields": [ "title", "description" ]
        }
    }

Is there any performance turning if choose one of two above?

Answer 1

It depends on the type parameter of your multi_match. In your example, since you didn't specify a type, best_fields is used. That makes use of a Dis Max Query and basically

uses the _score from the best field

On the other hand, your example with should

combines the _score from each field.

and it is equivalent to multi_match with type most_fields