Elasticsearch - give negative boost to documents without a certain field - elasticsearch

Question

I'm working on a query, the basic filtered multi match query is working as planned, it returns the documents i want.
The issue is that a want to boost results which have a certain string field with ex. 0.5, or in this example give results which don't have this field 'traded_as' a negative boost of 1.0.
Cannot get the filter - boost - must - exists/missing to work as i want.
It this the correct approach on this issue?
Using elasticsearch 1.5.2
{
"query": {
"filtered": {
"query": {
"multi_match": {
"query": "something",
"fields": ["title", "url", "description"]
}
},
"filter": {
"bool": {
"must": {
"missing": {
"field": "marked_for_deletion"
}
}
}
}
}
},
"boosting": {
"positive": {
"filter": {
"bool": {
"must": {
"exists": {
"field": "traded_as"
}
}
}
}
},
"negative": {
"filter": {
"bool": {
"must": {
"missing": {
"field": "traded_as"
}
}
}
}
},
"negative_boost": 1.0
}
}

Answer 1

You cannot have the desired result. As stated in the doc for boosting query :
Unlike the "NOT" clause in bool query, this still selects documents that contain undesirable terms, but reduces their overall score.
{
"query": {
"boosting": {
"positive": [{
"filtered": {
"query": {
"multi_match": {
"query": "something",
"fields": ["title", "url", "description"]
}
},
"filter": {
"bool": {
"must": [{
"missing": {
"field": "marked_for_deletion"
}
}]
}
}
}
}],
"negative": [{
"filtered": {
"filter": {
"missing": {
"field": "traded_as"
}
}
}
}],
"negative_boost": 1.0
}
}
}
So you'll still have some irrelevant documents, but matching documents will have a better score. You won't have any boost on traded_as presence that way. For this you should have a look at function score http://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-function-score-query.html#_using_function_score
You would have something like
{
"query": {
"function_score": {
"query": {
"filtered": {
"query": {
"multi_match": {
"query": "something",
"fields": ["title", "url", "description"]
}
},
"filter": {
"bool": {
"must": {
"missing": {
"field": "marked_for_deletion"
}
}
}
}
}
},
"functions": [{
"filter": {
"exists": {
"field": "traded_as"
}
},
"boost_factor": 2
}, {
"filter": {
"missing": {
"field": "traded_as"
}
},
"boost_factor": 0.5
}],
"score_mode": "first",
"boost_mode": "multiply"
}
}
}