如何在elasticsearch中获得最大的_id值?

问题描述

我们使用自定义的 _id 字段，该字段为 long 值.我想获得最大的_id值.我正在搜索的是-

We use a custom _id field which is a long value. I would like to get the max _id value. The search I am making is -

{
  "stored_fields": [
    "_id"
  ],
  "query": {
    "match_all": {}
  },
  "sort": {
    "_id": "desc"
  },
  "size": 1
}

但是我从ES 5.1 as-那里得到了错误-

But I get error back from ES 5.1 as-

"reason": {
              "type": "illegal_argument_exception",
              "reason": "Fielddata access on the _uid field is disallowed"
}

所以，我该如何获取 _id 的最大值.我并不是真的想将 _id 的副本存储在文档中只是为了获得最大值.

So, how do I go about getting the max value of _id. I don't really want to store copy of _id inside the doc just to get the max value.

推荐答案

您应按 _uid 字段而不是 _id 字段进行排序. _id 字段不可用于排序( https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-id-field.html ).

You should sort by the _uid field not by the _id field. The _id field is not accessible for sorting (https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-id-field.html).

{
  "stored_fields": [
    "_id"
  ],
  "query": {
    "match_all": {}
  },
  "sort": {
    "_uid": "desc"
  },
  "size": 1
}

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