Elasticsearch-23-_mapping复杂数据类型和object类型底层数据存储

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几种复杂的数据类型

multivalue field

比如数据是

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{"tags":["tag1","tag2"]}

这种数据建立索引时,与string类型是一样的, 数组中的数据是不能混的,要放字符串都放字符串.

empty field

比如 null, [], [null]这样的数据

object field

我们先来添加一个document

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PUT /company/emp/1
{
  "name":"jack",
  "age":27,
  "join_date":"2017-01-01",
  "address":{
    "country":"china",
    "province":"zhejiang",
    "city":"hangzhou"
  }
}

像上面这个address就是object类型的, 我们来看一下这个type的_mapping

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{
  "company": {
    "mappings": {
      "emp": {
        "properties": {
          "address": {
            "properties": {
              "city": {
                "type": "text",
                "fields": {
                  "keyword": {
                    "type": "keyword",
                    "ignore_above": 256
                  }
                }
              },
              "country": {
                "type": "text",
                "fields": {
                  "keyword": {
                    "type": "keyword",
                    "ignore_above": 256
                  }
                }
              },
              "province": {
                "type": "text",
                "fields": {
                  "keyword": {
                    "type": "keyword",
                    "ignore_above": 256
                  }
                }
              }
            }
          },
          "age": {
            "type": "long"
          },
          "join_date": {
            "type": "date"
          },
          "name": {
            "type": "text",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
              }
            }
          }
        }
      }
    }
  }
}

可以看到 address中的每个field都有对应的type等

其实像我们刚才添加的这个document,它的数据在es底层是像这样存储的

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{
    "name":[jack],
    "age":[27],
    "join_date":[2017-01-01],
    "address.country":[china],
    "address.province":[zhejiang],
    "address.city":[hangzhou]
}

再比如有更复杂的数据,比如下面我们再加一个,数据是

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{
    "authors": [
        { "age": 26, "name": "Jack White"},
        { "age": 55, "name": "Tom Jones"},
        { "age": 39, "name": "Kitty Smith"}
    ]
}

像这种包含json数组的数据,底层会从横向转为列式存储,就像这样

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{
    "authors.age":    [26, 55, 39],
    "authors.name":   [jack, white, tom, jones, kitty, smith]
}

就是一列存在一起