随机顺序分页弹性搜索 [英] Random order & pagination Elasticsearch

问题描述

在此问题中
是一个功能请求，可以选择种子进行排序为了娱乐随机顺序。

In this issue is a feature request for ordering with optional seed allowing for recreation of random order.

我需要能够分页随机排序的结果。
如何用Elasticsearch 0.19.1？

I need to be able to paginate random ordered results. How could this be be done with Elasticsearch 0.19.1 ?

谢谢。

推荐答案

您可以使用唯一字段的哈希函数（例如id）和随机盐进行排序。根据结果​​应该是多么真实随意，你可以做一些原始的例子：

You can sort using a hash function of a unique field (for example id) and a random salt. Depending on how truly random the results should be, you can do something as primitive as:

{
  "query" : { "query_string" : {"query" : "*:*"} },
  "sort" : {
    "_script" : { 
        "script" : "(doc['_id'].value + salt).hashCode()",
        "type" : "number",
        "params" : {
            "salt" : "some_random_string"
        },
        "order" : "asc"
    }
  }
}

或与

{
  "query" : { "query_string" : {"query" : "*:*"} },
  "sort" : {
    "_script" : { 
        "script" : "org.elasticsearch.common.Digest.md5Hex(doc['_id'].value + salt)",
        "type" : "string",
        "params" : {
            "salt" : "some_random_string"
        },
        "order" : "asc"
    }
  }
}

第二个例子将产生mor随机结果，但会稍慢一些。

The second example will produce more random results but will be somewhat slower.

对于这种工作方式，必须存储 _id 字段。否则，查询将以 NullPointerException 失败。

For this approach to work the field _id has to be stored. Otherwise, the query will fail with NullPointerException.

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