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Elasticsearch Search API

2018-12-17 10:46:59来源：博客园 阅读 ()

新老客户大回馈,云服务器低至5折

当执行一个搜索时，它将这个搜索请求广播给所有的索引分片。可以通过提供路由参数来控制要搜索哪些分片。例如，当检索tweets这个索引时，路由参数可以设置为用户名：

curl -X POST "localhost:9200/twitter/_search?routing=kimchy" -H 'Content-Type: application/json' -d'
{
    "query": {
        "bool" : {
            "must" : {
                "query_string" : {
                    "query" : "some query string here"
                }
            },
            "filter" : {
                "term" : { "user" : "kimchy" }
            }
        }
    }
}
'

1.  Search

查询可以提供一个简单的查询字符串作为参数，也可以用一个请求体。

1.1.  URI Search

这种方式用的很少，就不细说了，举个例子吧：

curl -X GET "localhost:9200/product/_search?q=category:honor&sort=price:asc"

1.2.  Request Body Search

同样，举个例子：

curl -X GET "localhost:9200/twitter/_search" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}
'

1.2.1.  Query

可以用 Query DSL 定义一个query

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}
'

1.2.2.  From / Size

通过 from 和 size 参数，可以分页查询。from 表示从第几条开始取，size 表示最多取多少条。from默认值是0，size默认值是10

curl -X GET "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "from" : 0, 
    "size" : 10,
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}
'

1.2.3.  Sort

可以按一个或多个字段排序

有一些特殊的排序字段：_score 表示按分数排序，_doc 表示按索引顺序排序

假设有这样一个索引：

curl -X PUT "localhost:9200/my_index" -H 'Content-Type: application/json' -d'
{
    "mappings": {
        "_doc": {
            "properties": {
                "post_date": { "type": "date" },
                "user": {
                    "type": "keyword"
                },
                "name": {
                    "type": "keyword"
                },
                "age": { "type": "integer" }
            }
        }
    }
}
'

针对这个索引，我们这样来查询：

curl -X GET "localhost:9200/my_index/_search" -H 'Content-Type: application/json' -d'
{
    "sort" : [
        { "post_date" : {"order" : "asc"}},
        "user",
        { "name" : "desc" },
        { "age" : "desc" },
        "_score"
    ],
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}
'

这个例子，依次按照 post_date升序、user升序、name降序、age降序、分数升序排序

（PS：_doc是最有效的排序，如果不关心文档的返回顺序的话）

Elasticsearch支持按数组或者多值字段排序，mode选项用来控制基于数组中的那个值来对文档进行排序。mode选项的可选值有：

  • min ：最小值
  • max ：最大值
  • sum ：用所有值的和来作为排序值
  • avg ：用所有值的平均值作为排序值
  • median ：用所有值的中间值作为排序值

举个例子：

curl -X PUT "localhost:9200/my_index/_doc/1?refresh" -H 'Content-Type: application/json' -d'
{
   "product": "chocolate",
   "price": [20, 4]
}
'
curl -X POST "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
   "query" : {
      "term" : { "product" : "chocolate" }
   },
   "sort" : [
      {"price" : {"order" : "asc", "mode" : "avg"}}
   ]
}
'

什么意思呢？也就说，字段的值可能是一个数组，或者该字段值有多个，那么当我们按这种字段排序的时候就必须确定在排序的时候这个字段的值是什么，也就是该字段的排序值

所谓的mode选项就是用来确定这种字段的最终排序值的，比如：取字段值数组中最小的那个值作为该字段的排序值，或者取最大、或者平均值等等

上面的例子中，price字段值是一个数组，数组有两个元素，后面的查询指定的mode是avg，意味着price字段在排序的时候它的排序值是 (20+4)/2=12

上例中，对结果集按price字段升序排序，price字段的排序值是price字段值求平均

Mission

mission 参数用于指定当文档没有这个字段时该如何处理，可选值是：_last 和 _first ，默认是 _last

类似于关系型数据库中字段为NULL的记录都放在最后

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "sort" : [
        { "price" : {"missing" : "_last"} }
    ],
    "query" : {
        "term" : { "product" : "chocolate" }
    }
}
'

1.2.4.  Source filtering

可以控制 _source 字段怎样返回

默认返回 _source字段的内容，当然你可以设置不返回该字段，例如：

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "_source": false,
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}
'

正常情况下，返回是这样的：

{
        "_index" : "product",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.0,
        "_source" : {
          "productName" : "Honor Note10",
          "category" : "Honor",
          "price" : 2499
        }
}

禁用后是这样的：

{
        "_index" : "product",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.0
}

还可以用通配符，以进一步控制_source中返回那些字段：

curl -X GET "localhost:9200/product/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "_source": "product*",
    "query" : {
        "match_all" : {}
    }
}
'

或者

curl -X GET "localhost:9200/product/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "_source": ["product*", "abc*"],
    "query" : {
        "match_all" : {}
    }
}
'

1.2.5.  高亮

curl -X GET "localhost:9200/product/_search?pretty" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "match" : { "category" : "MI" }
    },
    "highlight" : {
        "fields" : {
            "productName": {}
        }
    }
}
'

https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-highlighting.html

1.2.6.  Explain

执行计划可以看到分数是怎样计算出来的

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "explain": true,
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}
'

1.3.  Count

curl -X GET "localhost:9200/product/_doc/_count?pretty&q=category:honor"

curl -X GET "localhost:9200/product/_doc/_count?pretty" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "term" : { "category" : "honor" }
    }
}
'

{
  "count" : 3,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "skipped" : 0,
    "failed" : 0
  }
}

2.  Aggregations

相当于关系型数据库中的聚集函数（或者叫聚合函数）

聚合可以嵌套！聚合可以嵌套！！聚合可以嵌套！！！

聚合主要有4种类型：

  • Bucketing
  • Mertric
  • Matrix
  • Pipeline

基本的聚合结构是这样的：

aggregations 是一个JSON对象，它代表一个聚合。（PS：这个关键字也可以用 aggs )

  1. 每个聚合都关联了一个逻辑名称（例如：如果聚合计算平均价格，那么在这个场景下我可以给这个聚合起个名字叫“avg_price”）
  2. 在响应结果中，这些逻辑名称用于唯一标识一个聚合
  3. 每个聚合都有一个指定的类型（比如：sum ，avg ，max ，min 等等）
  4. 每个聚合类型都定义了自己的body

2.1.  Metrics Aggregations

这种类型的聚合是基于以某种方式从聚合的文档中提取的值来计算度量。这个值通常取自文档的字段值，也可以通过脚本计算得到的。

数值度量聚合是一种特殊的度量聚合，它输出数值。根据输出值的多少，分为单值数值度量聚合（比如：avg）和多值数值度量聚合（比如：stats）。

2.1.1.  Avg

从文档的数值字段中提取值进行计算

假设，我们的文档是学生成绩（0~100），我们可以求平均分数：

curl -X POST "localhost:9200/exams/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "aggs":{
        "avg_grade":{
            "avg":{
                "field":"grade"
            }
        }
    }
}
'

上面的聚合例子，计算所有学生的平均成绩。这里的聚合类型是avg，field指定哪个字段用于计算。

再来一个例子：

请求：
curl -X POST "localhost:9200/product/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "aggs":{
        "avg_price":{
            "avg":{
                "field":"price"
            }
        }
    }
}
'

响应：
{
    "took":13,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":7,
        "max_score":0,
        "hits":[

        ]
    },
    "aggregations":{
        "avg_price":{
            "value":2341.5714285714284
        }
    }
}

默认情况下，没有那个字段的文档将被忽略（PS：就像关系型数据库中求平均值时会忽略NULL的记录一样），我们可以给它指定一个值，例如：

curl -X POST "localhost:9200/exams/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "grade_avg" : {
            "avg" : {
                "field" : "grade",
                "missing": 10 
            }
        }
    }
}
'

如果文档没有grade字段，那么用10作为该字段值参与计算

2.1.2.  Sum

从文档的数值字段中提取值进行计算

请求：
curl -X POST "localhost:9200/product/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "query":{
        "constant_score":{
            "filter":{
                "match":{
                    "category":"vivo"
                }
            }
        }
    },
    "aggs":{
        "vivo_prices":{
            "sum":{
                "field":"price"
            }
        }
    }
}
'

响应：
{
    "took":3,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":2,
        "max_score":0,
        "hits":[

        ]
    },
    "aggregations":{
        "vivo_prices":{
            "value":3796
        }
    }
}

求category字段值匹配vivo的商品的价格总和

相当于，select sum(price) from product where category like '%vivo%' group by category

2.1.3.  Max

从文档的数值字段中提取值进行计算

curl -X POST "localhost:9200/sales/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "max_price" : { 
            "max" : { 
                "field" : "price" 
            } 
        }
    }
}
'

2.1.4.  Stats

这是一个多值聚合，它返回 min ，max ，sum ，count ，avg 的组合结果

curl -X POST "localhost:9200/exams/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "grades_stats" : { 
            "stats" : { 
                "field" : "grade" 
            } 
        }
    }
}
'

它的返回可能是这样的：

{
    ...

    "aggregations": {
        "grades_stats": {
            "count": 2,
            "min": 50.0,
            "max": 100.0,
            "avg": 75.0,
            "sum": 150.0
        }
    }
}

再来一个例子：

请求：
curl -X POST "localhost:9200/product/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "product_stats" : { 
            "stats" : { 
                "field" : "price" 
            } 
        }
    }
}
'

响应：
{
    "took":4,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":7,
        "max_score":0,
        "hits":[

        ]
    },
    "aggregations":{
        "product_stats":{
            "count":7,
            "min":998,
            "max":4299,
            "avg":2341.5714285714284,
            "sum":16391
        }
    }
}

2.2.  Bucket Aggregations

可以理解为范围聚合，它的结果是一段一段的，一个一个的bucket

2.2.1.  Range

每个Range包含from，不包含to

前闭后开区间

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "price_ranges" : {
            "range" : {
                "field" : "price",
                "ranges" : [
                    { "to" : 100.0 },
                    { "from" : 100.0, "to" : 200.0 },
                    { "from" : 200.0 }
                ]
            }
        }
    }
}
'

返回可能是这样的：

{
    ...
    "aggregations": {
        "price_ranges" : {
            "buckets": [
                {
                    "key": "*-100.0",
                    "to": 100.0,
                    "doc_count": 2
                },
                {
                    "key": "100.0-200.0",
                    "from": 100.0,
                    "to": 200.0,
                    "doc_count": 2
                },
                {
                    "key": "200.0-*",
                    "from": 200.0,
                    "doc_count": 3
                }
            ]
        }
    }
}

再比如：

请求：
curl -X GET "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "price_ranges" : {
            "range" : {
                "field" : "price",
                "ranges" : [
                    { "to" : 1000 },
                    { "from" : 1000, "to" : 2000 },
                    { "from" : 2000 }
                ]
            }
        }
    }
}
'

响应：
{
    "took":1,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":7,
        "max_score":1,
        "hits":[
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"5",
                "_score":1,
                "_source":{
                    "productName":"MI 8",
                    "category":"MI",
                    "price":2499
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"2",
                "_score":1,
                "_source":{
                    "productName":"Honor Magic2",
                    "category":"Honor",
                    "price":4299
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"4",
                "_score":1,
                "_source":{
                    "productName":"MI Max2",
                    "category":"MI",
                    "price":1099
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"6",
                "_score":1,
                "_source":{
                    "productName":"vivo X23",
                    "category":"vivo",
                    "price":2798
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"1",
                "_score":1,
                "_source":{
                    "productName":"Honor 10",
                    "category":"Honor",
                    "price":2199
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"7",
                "_score":1,
                "_source":{
                    "productName":"vivo Z1",
                    "category":"vivo",
                    "price":998
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"3",
                "_score":1,
                "_source":{
                    "productName":"Honor Note10",
                    "category":"Honor",
                    "price":2499
                }
            }
        ]
    },
    "aggregations":{
        "price_ranges":{
            "buckets":[
                {
                    "key":"*-1000.0",
                    "to":1000,
                    "doc_count":1
                },
                {
                    "key":"1000.0-2000.0",
                    "from":1000,
                    "to":2000,
                    "doc_count":1
                },
                {
                    "key":"2000.0-*",
                    "from":2000,
                    "doc_count":5
                }
            ]
        }
    }
}

代替返回一个数组，可以设置keyed为true，这样可以给每个bucket关联一个位于的字符串key，例如：

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "price_ranges" : {
            "range" : {
                "field" : "price",
                "keyed" : true,
                "ranges" : [
                    { "to" : 100 },
                    { "from" : 100, "to" : 200 },
                    { "from" : 200 }
                ]
            }
        }
    }
}
'

于是返回变成这样了：

{
    ...
    "aggregations": {
        "price_ranges" : {
            "buckets": {
                "*-100.0": {
                    "to": 100.0,
                    "doc_count": 2
                },
                "100.0-200.0": {
                    "from": 100.0,
                    "to": 200.0,
                    "doc_count": 2
                },
                "200.0-*": {
                    "from": 200.0,
                    "doc_count": 3
                }
            }
        }
    }
}

当然，我们也可以给每个范围区间自定义key：

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "price_ranges" : {
            "range" : {
                "field" : "price",
                "keyed" : true,
                "ranges" : [
                    { "key" : "cheap", "to" : 100 },
                    { "key" : "average", "from" : 100, "to" : 200 },
                    { "key" : "expensive", "from" : 200 }
                ]
            }
        }
    }
}
'

返回：

{
    ...
    "aggregations": {
        "price_ranges" : {
            "buckets": {
                "cheap": {
                    "to": 100.0,
                    "doc_count": 2
                },
                "average": {
                    "from": 100.0,
                    "to": 200.0,
                    "doc_count": 2
                },
                "expensive": {
                    "from": 200.0,
                    "doc_count": 3
                }
            }
        }
    }
}

举个栗子：

请求：
curl -X GET "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "query": {
        "match" : { "category" : "honor"}
    },
    "aggs" : {
        "price_ranges" : {
            "range" : {
                "field" : "price",
                "keyed" : true,
                "ranges" : [
                    { "key" : "low", "to" : 1000 },
                    { "key" : "medium", "from" : 1000, "to" : 2000 },
                    { "key" : "high", "from" : 2000 }
                ]
            }
        }
    }
}
'

响应：
{
    "took":1,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":3,
        "max_score":0.9808292,
        "hits":[
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"2",
                "_score":0.9808292,
                "_source":{
                    "productName":"Honor Magic2",
                    "category":"Honor",
                    "price":4299
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"1",
                "_score":0.6931472,
                "_source":{
                    "productName":"Honor 10",
                    "category":"Honor",
                    "price":2199
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"3",
                "_score":0.2876821,
                "_source":{
                    "productName":"Honor Note10",
                    "category":"Honor",
                    "price":2499
                }
            }
        ]
    },
    "aggregations":{
        "price_ranges":{
            "buckets":{
                "low":{
                    "to":1000,
                    "doc_count":0
                },
                "medium":{
                    "from":1000,
                    "to":2000,
                    "doc_count":0
                },
                "high":{
                    "from":2000,
                    "doc_count":3
                }
            }
        }
    }
}

2.2.2.  Filter

先过滤再聚合

请求：
curl -X POST "localhost:9200/product/_search?size=0" -H 'Content-Type: application/json' -d'
{
    "aggs":{
        "vivo":{
            "filter":{
                "term":{
                    "category":"vivo"
                }
            },
            "aggs":{
                "avg_price":{
                    "avg":{
                        "field":"price"
                    }
                }
            }
        }
    }
}
'

响应：
{
    "took":2,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":7,
        "max_score":0,
        "hits":[

        ]
    },
    "aggregations":{
        "vivo":{
            "doc_count":2,
            "avg_price":{
                "value":1898
            }
        }
    }
}

2.2.3.  Terms Aggregation

相当于关系型数据库中的分组（group by）

curl -X GET "localhost:9200/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "genres" : {
            "terms" : { "field" : "genre" }
        }
    }
}
'

返回可能是这样的：

{
    ...
    "aggregations" : {
        "genres" : {
            "doc_count_error_upper_bound": 0, 
            "sum_other_doc_count": 0, 
            "buckets" : [ 
                {
                    "key" : "electronic",
                    "doc_count" : 6
                },
                {
                    "key" : "rock",
                    "doc_count" : 3
                },
                {
                    "key" : "jazz",
                    "doc_count" : 2
                }
            ]
        }
    }
}

再举个例子：

请求：
curl -X GET "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "group_by_category" : {
            "terms" : { "field" : "category" }
        }
    }
}
'

响应：
{
    "took":16,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":7,
        "max_score":1,
        "hits":[
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"5",
                "_score":1,
                "_source":{
                    "productName":"MI 8",
                    "category":"MI",
                    "price":2499
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"2",
                "_score":1,
                "_source":{
                    "productName":"Honor Magic2",
                    "category":"Honor",
                    "price":4299
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"4",
                "_score":1,
                "_source":{
                    "productName":"MI Max2",
                    "category":"MI",
                    "price":1099
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"6",
                "_score":1,
                "_source":{
                    "productName":"vivo X23",
                    "category":"vivo",
                    "price":2798
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"1",
                "_score":1,
                "_source":{
                    "productName":"Honor 10",
                    "category":"Honor",
                    "price":2199
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"7",
                "_score":1,
                "_source":{
                    "productName":"vivo Z1",
                    "category":"vivo",
                    "price":998
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"3",
                "_score":1,
                "_source":{
                    "productName":"Honor Note10",
                    "category":"Honor",
                    "price":2499
                }
            }
        ]
    },
    "aggregations":{
        "group_by_category":{
            "doc_count_error_upper_bound":0,
            "sum_other_doc_count":0,
            "buckets":[
                {
                    "key":"honor",
                    "doc_count":3
                },
                {
                    "key":"mi",
                    "doc_count":2
                },
                {
                    "key":"vivo",
                    "doc_count":2
                }
            ]
        }
    }
}

size 可以用于指定返回多少个term bucket

请求：
curl -X GET "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "group_by_category" : {
            "terms" : { 
                "field" : "category",
                "size" : 2
            }
        }
    }
}
'

响应：
{
    ...
    
    "aggregations":{
        "group_by_category":{
            "doc_count_error_upper_bound":0,
            "sum_other_doc_count":2,
            "buckets":[
                {
                    "key":"honor",
                    "doc_count":3
                },
                {
                    "key":"mi",
                    "doc_count":2
                }
            ]
        }
    }
}

3.  示例

排序

curl -X POST "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "term" : { "category" : "honor"}
    },
    "sort" : "price"
}

'
curl -X POST "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "term" : { "category" : "honor"}
    },
    "sort" : { "price" : "desc" }
}
'

curl -X POST "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "query" : {
        "term" : { "category" : "honor"}
    },
    "sort" : { "price" : { "order" : "desc" } }
}
'

响应：
{
    "took":1,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":3,
        "max_score":null,
        "hits":[
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"2",
                "_score":null,
                "_source":{
                    "productName":"Honor Magic2",
                    "category":"Honor",
                    "price":4299
                },
                "sort":[
                    4299
                ]
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"3",
                "_score":null,
                "_source":{
                    "productName":"Honor Note10",
                    "category":"Honor",
                    "price":2499
                },
                "sort":[
                    2499
                ]
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"1",
                "_score":null,
                "_source":{
                    "productName":"Honor 10",
                    "category":"Honor",
                    "price":2199
                },
                "sort":[
                    2199
                ]
            }
        ]
    }
}

分组求平均

请求：
curl -X GET "localhost:9200/product/_search" -H 'Content-Type: application/json' -d'
{
    "aggs" : {
        "group_by_category" : {
            "terms" : { 
                "field" : "category"
            },
            "aggs" : {
                "avg_price" : {
                    "avg" : {
                        "field" : "price"
                    }
                }
            }
        }
    }
}
'

响应：
{
    "took":2,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "skipped":0,
        "failed":0
    },
    "hits":{
        "total":7,
        "max_score":1,
        "hits":[
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"5",
                "_score":1,
                "_source":{
                    "productName":"MI 8",
                    "category":"MI",
                    "price":2499
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"2",
                "_score":1,
                "_source":{
                    "productName":"Honor Magic2",
                    "category":"Honor",
                    "price":4299
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"4",
                "_score":1,
                "_source":{
                    "productName":"MI Max2",
                    "category":"MI",
                    "price":1099
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"6",
                "_score":1,
                "_source":{
                    "productName":"vivo X23",
                    "category":"vivo",
                    "price":2798
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"1",
                "_score":1,
                "_source":{
                    "productName":"Honor 10",
                    "category":"Honor",
                    "price":2199
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"7",
                "_score":1,
                "_source":{
                    "productName":"vivo Z1",
                    "category":"vivo",
                    "price":998
                }
            },
            {
                "_index":"product",
                "_type":"_doc",
                "_id":"3",
                "_score":1,
                "_source":{
                    "productName":"Honor Note10",
                    "category":"Honor",
                    "price":2499
                }
            }
        ]
    },
    "aggregations":{
        "group_by_category":{
            "doc_count_error_upper_bound":0,
            "sum_other_doc_count":0,
            "buckets":[
                {
                    "key":"honor",
                    "doc_count":3,
                    "avg_price":{
                        "value":2999
                    }
                },
                {
                    "key":"mi",
                    "doc_count":2,
                    "avg_price":{
                        "value":1799
                    }
                },
                {
                    "key":"vivo",
                    "doc_count":2,
                    "avg_price":{
                        "value":1898
                    }
                }
            ]
        }
    }
}

4.  示例索引

curl -X PUT "localhost:9200/product" -H 'Content-Type: application/json' -d'
{
    "mappings" : {
        "_doc" : {
            "properties": {
                "productName": {"type": "text"},
                "category": {"type": "text", "fielddata": true},
                "price": {"type": "integer"}
            }
        }
    }
}
'

curl -X POST "localhost:9200/product/_doc/_bulk" -H 'Content-Type: application/json' --data-binary "@product.json"


{"index" : {"_id" : "1" } }
{"productName" : "Honor 10", "category" : "Honor", "price" : 2199}
{"index" : {"_id" : "2" } }
{"productName" : "Honor Magic2", "category" : "Honor", "price" : 4299}
{"index" : {"_id" : "3" } }
{"productName" : "Honor Note10", "category" : "Honor", "price" : 2499}
{"index" : {"_id" : "4" } }
{"productName" : "MI Max2", "category" : "MI", "price" : 1099}
{"index" : {"_id" : "5" } }
{"productName" : "MI 8", "category" : "MI", "price" : 2499}
{"index" : {"_id" : "6" } }
{"productName" : "vivo X23", "category" : "vivo", "price" : 2798}
{"index" : {"_id" : "7" } }
{"productName" : "vivo Z1", "category" : "vivo", "price" : 998}

5.  参考

https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics.html

https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket.html

6.  其它相关

《Elasticsearch查询》

 

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