Elasticsearch Subquery Scoring Optimization

If you want to build a search query in Easticsearch where you can give documents a bonus score depending on how often a property can be found in other documents

– you need is a Subquery which is not supported by Elasticsearch, you need another better solution.

An Example for a Subquery is the problem:

Imagine a CD online shop. You want to score CDs ( = documents) higher which

1. match a term query AND

2. and which artist has many other CDs in your shop database

You would need a field, which aggragts the artist count in your mapping (artistCount for Example) and on query time and boost the artistCount field with the score:

{
    "query" : {
        "custom_score" : {
            "query" : {
                "match_all" : {}
            },
            "script" : "_score + (1 * doc.artistCount.integerValue)"
        }
    }
}

It would be also a good idea, to have a second index, which holds the artistCount information, because on every update of the inventory of your shop, the artsitCount needs to be recalculated.