# Min Bucket Aggregation

原文链接 : [https://www.elastic.co/guide/en/elasticsearch/reference/5.4/search-aggregations-pipeline-min-bucket-aggregation.html](https://www.elastic.co/guide/en/elasticsearch/reference/5.4/search-aggregations-pipeline-min-bucket-aggregation.html)

译文链接 : [Min Bucket Aggregation](/display/Elasticsearch/Min+Bucket+Aggregation)

贡献者 : @苏涛，[ApacheCN](/display/~apachecn)，[Apache中文网](/display/~apachechina)

警告

此功能是实验性的，可能会在将来的版本中完全更改或删除。Elastic将采取最大的努力来解决此问题，但实验功能不受SLA官方功能的支持。

最小分组聚合所定义的桶包含一组聚合指定度量的最小值，并且同时输出桶的键和值。指定的度量必须是数字型而且这个组聚合必须是多桶聚合。

### 语法

min_bucket聚合结构如下：

```
{
    "min_bucket": {
        "buckets_path": "the_sum"
    }
}
```

`min_bucket参数如下：`

| 参数名称 | 描述 | 是否必填 | 默认值 |
| --- | --- | --- | --- |
| buckets_path | 想要计算最小值的桶路径，点击 [the section called “`buckets_path` Syntax](https://www.elastic.co/guide/en/elasticsearch/reference/5.4/search-aggregations-pipeline.html#buckets-path-syntax "buckets_path Syntaxedit")[edit](https://github.com/elastic/elasticsearch/edit/5.4/docs/reference/aggregations/pipeline.asciidoc "Edit this page on GitHub")”查看更多细节 | 必填 |   |
| gap_policy | 当数据缺口出现时采用的策略，点击[the section called “Dealing with gaps in the data](https://www.elastic.co/guide/en/elasticsearch/reference/5.4/search-aggregations-pipeline.html#gap-policy "Dealing with gaps in the dataedit")[edit](https://github.com/elastic/elasticsearch/edit/5.4/docs/reference/aggregations/pipeline.asciidoc "Edit this page on GitHub")”查看更多细节 | 可选 | skip |
| format | 用于规范聚合输出值的格式 | 可选 | null |

 以下代码段计算每月总销售额的最小值：

```
POST /sales/_search
{
    "size": 0,
    "aggs" : {
        "sales_per_month" : {
            "date_histogram" : {
                "field" : "date",
                "interval" : "month"
            },
            "aggs": {
                "sales": {
                    "sum": {
                        "field": "price"
                    }
                }
            }
        },
        "min_monthly_sales": {
            "min_bucket": {
                "buckets_path": "sales_per_month>sales" #1
            }
        }
    }
}

```

| 1 | buckets_path指示这个min_bucket聚合是要得到sales_per_month日期直方图中sales聚合的最小值。 |

可能得到如下的响应：

```
{
   "took": 11,
   "timed_out": false,
   "_shards": ...,
   "hits": ...,
   "aggregations": {
      "sales_per_month": {
         "buckets": [
            {
               "key_as_string": "2015/01/01 00:00:00",
               "key": 1420070400000,
               "doc_count": 3,
               "sales": {
                  "value": 550.0
               }
            },
            {
               "key_as_string": "2015/02/01 00:00:00",
               "key": 1422748800000,
               "doc_count": 2,
               "sales": {
                  "value": 60.0
               }
            },
            {
               "key_as_string": "2015/03/01 00:00:00",
               "key": 1425168000000,
               "doc_count": 2,
               "sales": {
                  "value": 375.0
               }
            }
         ]
      },
      "min_monthly_sales": {
          "keys": ["2015/02/01 00:00:00"], #1
          "value": 60.0
      }
   }
}
```

| 1 | key是字符串数组，因为最小值可能存在于多个存储桶中 |