『备忘录』elasticsearch 去重分页查询

一开始数据结构设计的很复杂，又是父子关系又是嵌套关系，结果发现不能通过简单的查询得到想要的结果：比如一个商店只出现一件符合条件的商品，弄得查询语句就变成这样了

curl -XPOST http://localhost:9200/bnb_shop_room/_search -H 'Content-Type:application/json' -d'
{
  "query":{
    "bool":{
      "must":[
        {"match":{"shop_name":"民宿"}},
        {"has_child":{
          "type":"roomBase",
          "query": {
            "bool":{
              "must":[
                {"has_child":
                  {
                    "type":"roomPrice",
                    "query":{
                      "bool":{
                        "must":[
                          {
                              "nested":{
                                "path":"room_prices",
                                "query": {
                                  "bool":{
                                    "must":[
                          {
                              "range":{
                                  "room_prices.date":{
                                      "gt":"2018-03-24",
                                      "lt":"2019-09-26"
                                  }
                              }
                          },
                          {
                              "term":{
                                  "room_prices.status":1
                              }
                          },
                          {
                              "range":{
                                  "room_prices.price":{
                                      "gt":0
                                  }
                              }
                          }
                                    ]
                                  }
                                }
                              }
                          }
                        ]
                      }
                    }
                  }
              }
              ]
            }
          }
          }
        }
      ]
    }
  },
  "size":5,
  "from":0,
  "sort": [
    {
      "_geo_distance": {
        "shop_location" : {
            "lat" : "22.5971370000",
            "lon" : "114.5201730000"
        },
        "order": "asc",
        "unit": "m"
      }
    }
  ],
  "aggs": {
    "shop": {
      "terms": { 
        "field" : "shop_id"
      },
      "aggs": {
        "room": {
          "children": { 
            "type": "roomBase"
          },
          "aggs": {
            "price": {
              "children": { 
                "type": "roomPrice"
              },
              "aggs": {
                "nestedPrice": {
                  "nested": {
                    "path": "room_prices"
                  },
                  "aggs": {
                    "statsPrice": {
                        "stats": { 
                          "field": "room_prices.price"
                        }
                      }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}'

最后改了索引信息的结构，不做关联关系，全部平铺，冗余数据，发现查询语句简单多了，查询语句变成如下：

curl -XPOST http://localhost:9200/shop_room_day/_doc/_search -H 'Content-Type:application/json' -d'
{
  "query":{
    "bool":{
      "must":[
          {"match":{"shop_name":"主题 深圳"}},
          {
            "range":{
                  "day_date":{
                      "gt":"2018-03-27",
                      "lt":"2018-03-29"
                  }
              }
          },
          {
              "term":{
                  "day_status":1
              }
          },
          {
              "range":{
                  "day_price":{
                      "gt":0
                  }
              }
          }
      ]
    }
  },
  "sort": [
    {"day_price":{"order":"asc"}},
    {
      "_geo_distance": {
        "shop_location" : {
            "lat" : "22.5971370000",
            "lon" : "114.5201730000"
        },
        "order": "asc",
        "unit": "m"
      }
    }
  ],
  "collapse": {
    "field": "shop_id"
  },
  "size":2,
  "from":0
}'

用 『collapse』功能能从搜索结果中去重，翻页靠『size』和『from』组合，当然也可以用『scroll』的方式实现翻页效果

折叠『collapse』功能推荐这篇案例文章：「Elasticsearch 5.x 字段折叠的使用」 https://elasticsearch.cn/article/132

分页『scroll』功能推荐这篇案例文章：「elasticsearch 深分页问题以及解决方法」https://blog.csdn.net/wild46cat/article/details/64123353