note

• 干货 | Elasticsearch Nested类型深入详解
• elasticsearch（lucene）使用的库没有内部对象的概念，因此内部对象被扁平化为一个简单的字段名称和值列表。
• 为了解决这个问题，需要用到 nested，nested对象会被作为隐式对象处理。其内容不会被扁平化处理。
• 关联 doc 必须保存于同一个分片，所以在构建 index的时候，需要添加 routing=parent_id 参数

demo

nested

DELETE /netest_index
PUT /netest_index
{
  "mappings": {
    "properties": {
      "title":{
        "type":"text"
      },
      "comments": {
        "type": "nested",
        "properties": {
          "name":{
            "type":"text"
          },
          "comment":{
            "type":"text"
          }
        }
      }
    }
  }
}

POST /netest_index/_doc/1
{
  "title":"es",
  "comments":[ 
    {
      "name": "zhengcj",
      "count": 6
    },
    {
      "name":"dongyc",
      "count":1
    }
  ]
}

POST /netest_index/_doc/2
{
  "title":"java",
  "comments": [
    {
      "name": "zhengcj",
      "count": 6
    },
    {
      "name":"ljr",
      "count":2
    }
  ]
}

GET /netest_index/_search
{
    "query": {
        "nested" : {
            "path" : "comments",
            "query" : {
                "bool" : {
                    "must" : [
                    { "match" : {"comments.name" : "zhengcj"} },
                    { "range" : {"comments.count" : {"gte" : 6}} }
                    ]
                }
            },
            "score_mode" : "avg"
        }
    }
}

POST netest_index/_update/1
{
  "script": {
    "lang": "painless",
    "source": "ctx._source.comments.removeIf(it->it.name=='dongyc')"
  }
}

POST /netest_index/_update/1
{
  "script":{
    "source": "for(e in ctx._source.comments){if(e.name=='zhengcj'){e.count+=1;}}"
  }
}

GET /netest_index/_search
{
  "size": 0,
  "aggs":{
    "nested_aggs":{
      "nested":{
        "path":"comments"
      },
      "aggs":{
        "min_count":{
          "min":{
            "field":"comments.count"
          }
        }
      }
    }
  }
}

join/has_parent/has_child

init data

DELETE stack_overflow
PUT stack_overflow
{
  "mappings": {
    "properties": {
      "join": {
        "type": "join",
        "relations": {
          "question": "answer"
        }
      },
      "key":{
        "type": "keyword"
      },
      "view_count":{
        "type":"integer"
      }
    }
  }
}

PUT stack_overflow/_doc/1
{
  "join": {
    "name": "question"
  },
  "body": "<p>I have Windows 2003 server and i bought a new Windows 2008 server...",
  "title": "Whats the best way to file transfer my site from server to a newer one?",
  "tags": [
    "windows-server-2003",
    "windows-server-2008",
    "file-transfer"
  ],
  "key":"2003-2008",
  "view_count":10
}

PUT stack_overflow/_doc/2
{
  "join": {
    "name": "question"
  },
  "body": "ELK body",
  "title": "ELK",
  "tags": [
    "es",
    "kibana",
    "logstash"
  ],
  "key":"ELK",
  "view_count":2
}

# 必须包含 routing=n，关联 doc 必须保存于同一个分片
PUT stack_overflow/_doc/11?routing=1
{
  "join": {
    "name": "answer",
    "parent": "1"
  },
  "owner": {
    "location": "Norfolk, United Kingdom",
    "display_name": "Sam",
    "id": 48
  },
  "body": "<p>Unfortunately you're pretty much limited to FTP...",
  "creation_date": "2009-05-04T13:45:37.030",
  "key":"FTP",
  "view_count":3
}

PUT stack_overflow/_doc/12?routing=1&refresh
{
  "join": {
    "name": "answer",
    "parent": "1"
  },
  "owner": {
    "location": "Norfolk, United Kingdom",
    "display_name": "Troll",
    "id": 49
  },
  "body": "<p>Use Linux...",
  "creation_date": "2009-05-05T13:45:37.030",
  "key":"Linux",
  "view_count":4
}

PUT stack_overflow/_doc/21?routing=2
{
  "join": {
    "name": "answer",
    "parent": "2"
  },
  "owner": {
    "location": "Norfolk, United Kingdom",
    "display_name": "Sam",
    "id": 48
  },
  "body": "this is answer to es in body",
  "creation_date": "2009-05-04T13:45:37.030",
  "key":"es",
  "view_count":5
}

join

查询一个人回答过问题的标签，即这个人关注的问题

POST stack_overflow/_search?size=0
{
  "aggs": {
    "top-names": {
      "terms": {
        "field": "owner.display_name.keyword",
        "size": 10
      },
      "aggs": {
        "to-questions": {
          "parent": {
            "type": "answer"
          },
          "aggs": {
            "top-tags": {
              "terms": {
                "field": "tags.keyword",
                "size": 10
              }
            }
          }
        }
      }
    }
  }
}

has_parent

根据 parent是否满足条件，返回child

GET /stack_overflow/_search
{
  "query": {
    "has_parent": {
      "parent_type": "question",
      "query": {
        "term": {
          "key": {
            "value": "ELK"
          }
        }
      }
    }
  }
}

GET /stack_overflow/_search
{
  "query": {
    "has_parent": {
      "parent_type": "question",
      "score":true,
      "query": {
        "function_score": {
          "script_score": {
            "script": "_score * doc['view_count'].value+1"
          }
        }
      }
    }
  }
}

has_child

根据 child是否满足条件，返回parent

GET /stack_overflow/_search
{
  "query": {
    "has_child": {
      "type": "answer",
      "query": {
        "match_all": {}
      },
      "max_children": 5,
      "min_children": 2,
      "score_mode": "min"
    }
  }
}