如何按照Elasticsearch中的孩子数量对父母进行排序 [英] How to sort parents by number of children in Elasticsearch

问题描述

我的索引中有 parent / child 相关的文档，并希望得到按照号码排序的父母列表的孩子。有没有办法呢？我正在使用 Elasticsearch 1.5.1

I have parent/child-related documents in my index and want to get list of parents sorted by number of children. Is it any way to do it? I'm using Elasticsearch 1.5.1

现在我可以很容易地获得与父查询一起的子文档数结果使用 inner_hits 功能，但似乎没有办法从脚本或搜索/访问 inner_hits。{child_type_name} .hits.total 得分功能。任何想法？

Right now I can easily get number of children documents together with parent query results by using inner_hits feature, but it seems no way to access inner_hits.{child_type_name}.hits.total value from the script or search/score function. Any ideas?

推荐答案

嗯，我发现回答自己，终于。感谢@doctorcal在 #flasticsearch 上的提示IRC

Well, I found answer myself, finally. Thanks to hints from @doctorcal on #elasticsearch IRC

正如我在问题中提到的，我们可以使用 Elasticsearch 1.5中的inner-hits.htmlrel =nofollow> inner_hits 。

As I mentioned in the question, we can get list of children together with each parent using inner_hits in Elasticsearch 1.5.

能够按照他们的孩子的数量对父母进行排序，我们需要使用一个小技巧 - 把孩子的数量放入父母的分数（默认情况下用于排序）。为此，我们只是使用的分数模式 has_child 查询：

To be able to sort parents by number of their children we need to use a small trick - put number of children into the parent's score (which is used to sort by default). For that, we just use the score mode sum for has_child query:

{
    "query": {
        "has_child": {
            "type": "comment",
            "score_mode": "sum",
            "query": {
                "match_all": {}
            },
            "inner_hits": {}
        }
    }
}

注意：此查询有一个限制 - 似乎您不能保留关于初始分数（查询的相关性分数）的信息，因为我们替换他们有孩子的数量。

NOTE: this query has a limitation - it seems you can't keep information about initial scores (relevance scores for the query), since we replace them with number of children.

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